lago package

Subpackages

• lago.plugins package
  • Submodules
  • lago.plugins.cli module
  • lago.plugins.output module
  • lago.plugins.service module
  • lago.plugins.vm module
• lago.providers package
  • Subpackages
    • lago.providers.libvirt package
      • Submodules
      • lago.providers.libvirt.cpu module
      • lago.providers.libvirt.network module
      • lago.providers.libvirt.utils module
      • lago.providers.libvirt.vm module

Submodules

lago.brctl module

lago.brctl._brctl(command, *args)

lago.brctl._set_link(name, state)

lago.brctl.create(name, stp=True)

lago.brctl.destroy(name)

lago.brctl.exists(name)

lago.build module

class lago.build.Build(name, disk_path, paths)

Bases: object

A Build object represents a build section in the init file. Each build section (which in turn belongs to a specific disk) should get his own Build object

In order to add support for a new build command, a new function with the name of the command should be implemented in this class. this function should accept a list of options and arguments and return a named tuple ‘Command’, where ‘Command.name’ is the name of the command and ‘Command.cmd’ is the a list containing the command and its args, for example: Command.name = ‘virt-customize’ Command.cmd = [‘virt-customize’, ‘-a’, PATH_TO_DISK, SOME_CMDS…]

name

The name of the vm this builder belongs

Type:str

disk_path

The path to the disk that needs to be customized

Type:str

paths

The paths of the current prefix

Type:lago.paths.Paths

build_cmds

A list of commands that should be invoked on the disk located in disk_path

Type:list of str

build()

Run all the commands in self.build_cmds

Raises:lago.build.BuildException – If a command returned a non-zero code

get_cmd_handler(cmd)

Return an handler for cmd. The handler and the command should have the same name. See class description for more info about handlers.

Parameters:cmd (str) – The name of the command Returns:which handles cmd Return type:callable Raises:lago.build.BuildException – If an handler for cmd doesn’t exist

classmethod get_instance_from_build_spec(name, disk_path, build_spec, paths)

Parameters:

• name (str) – The name of the vm this builder belongs
• disk_path (str) – The path to the disk that needs to be customized
• paths (lago.paths.Paths) – The paths of the current prefix
• build_spec (dict) – The build spec part, associated with the disk located at disk_path, from the init file.

Returns:

An instance of Build with a normalized build spec i.e ready to

be invoked.

normalize_build_spec(build_spec)

Convert a build spec into a list of Command tuples. After running this command, self.build_cmds should hold all the commands that should be run on the disk in self.disk_path.

Parameters:build_spec (dict) – The buildspec part from the init file

static normalize_options(options)

Turns a mapping of ‘option: arg’ to a list and prefix the options. arg can be a list of arguments.

for example:

dict = {

o1: a1, o2: , o3: [a31, a32] o4: []

}

will be transformed to:

[

prefix_option(o1), a1, prefix_option(o2), prefix_option(o3), a31, prefix_option(o3), a32 prefix_option(o4)

]

note that empty arguments are omitted

Parameters:options (dict) – A mapping between options and arguments Returns:A normalized version of ‘options’ as mentioned above Return type:lst

static prefix_option(option)

Depends on the option’s length, prefix it with ‘-‘ or ‘–’ :param option: The option to prefix :type option: str

Returns:prefixed option Return type:str

virt_customize(options)

Handler for ‘virt-customize’ note: if ‘ssh-inject’ option was specified without a path to a key, the prefix’ key will be copied to the vm.

Parameters:options (lst of str) – Options and arguments for ‘virt-customize’ Returns:which handles cmd Return type:callable Raises:lago.build.BuildException – If an handler for cmd doesn’t exist

exception lago.build.BuildException

Bases: lago.utils.LagoException

class lago.build.Command(name, cmd)

Bases: tuple

__getnewargs__()

Return self as a plain tuple. Used by copy and pickle.

__getstate__()

Exclude the OrderedDict from pickling

__repr__()

Return a nicely formatted representation string

_asdict()

Return a new OrderedDict which maps field names to their values

_fields = ('name', 'cmd')

classmethod _make(iterable, new=<built-in method __new__ of type object>, len=<built-in function len>)

Make a new Command object from a sequence or iterable

_replace(**kwds)

Return a new Command object replacing specified fields with new values

cmd

Alias for field number 1

name

Alias for field number 0

lago.cmd module

lago.cmd.create_parser(cli_plugins, out_plugins)

lago.cmd.exit_handler(signum, frame)

Catch SIGTERM and SIGHUP and call “sys.exit” which raises “SystemExit” exception. This will trigger all the cleanup code defined in ContextManagers and “finally” statements.

For more details about the arguments see “signal” documentation.

Parameters:

• signum (int) – The signal’s number
• frame (frame) – The current stack frame, can be None

lago.cmd.main()

lago.config module

class lago.config.ConfigLoad(root_section='lago', defaults={})

Bases: object

Merges configuration parameters from 3 different sources: 1. Enviornment vairables 2. config files in .INI format 3. argparse.ArgumentParser

The assumed order(but not necessary) order of calls is: load() - load from config files and environment variables update_parser(parser) - update from the declared argparse parser update_args(args) - update from passed arguments to the parser

__getitem__(key)

Get a variable from the default section, good for fail-fast if key does not exists.

Parameters:key (str) – key Returns:config variable Return type:str

get(*args)

Get a variable from the default section :param *args: dict.get() args :type *args: args

Returns:config variable Return type:str

get_ini(incl_unset=False)

Return the config dictionary in INI format :param incl_unset: include variables with no defaults. :type incl_unset: bool

Returns:string of the config file in INI format Return type:str

get_section(*args)

get a section dictionary Args:

Returns:section config dictionary Return type:dict

load()

Load all configurations from available resources, skip if empty:

1. default` dict passed to ConfigLoad.__init__().

2. Custom paths as defined in CONFS_PATH in

   constants.

3. XDG standard paths.
4. Environment variables.

Returns:dict of dicts. Return type:dict

update_args(args)

Update config dictionary with parsed args, as resolved by argparse. Only root positional arguments that already exist will overridden.

Parameters:args (namespace) – args parsed by argparse

update_parser(parser)

Update config dictionary with declared arguments in an argparse.parser New variables will be created, and existing ones overridden.

Parameters:parser (argparse.ArgumentParser) – parser to read variables from

lago.config._get_configs_path()

Get a list of possible configuration files, from the following sources: 1. All files that exists in constants.CONFS_PATH. 2. All XDG standard config files for “lago.conf”, in reversed order of importance.

Returns:list of files Return type:list(str)

lago.config.get_env_dict(root_section)

Read all Lago variables from the environment. The lookup format is: LAGO_VARNAME - will land into ‘lago’ section LAGO__SECTION1__VARNAME - will land into ‘section1’ section, notice the double ‘__’. LAGO__LONG_SECTION_NAME__VARNAME - will land into ‘long_section_name’

Returns:dict of section configuration dicts Return type:dict

Examples

>>> os.environ['LAGO_GLOBAL_VAR'] = 'global'
>>> os.environ['LAGO__INIT__REPO_PATH'] = '/tmp/store'
>>>
>>> config.get_env_dict()
{'init': {'repo_path': '/tmp/store'}, 'lago': {'global_var': 'global'}}

lago.constants module

lago.constants.CONFS_PATH = ['/etc/lago/lago.conf']

CONFS_PATH - default path to first look for configuration files.

lago.constants.LIBEXEC_DIR = '/usr/libexec/lago/'

LIBEXEC_DIR -

lago.export module

class lago.export.DiskExportManager(dst, disk_type, disk, do_compress)

Bases: object

DiskExportManager object is responsible on the export process of an image from the current Lago prefix.

DiskExportManger is the base class of specific DiskExportManger. Each specific DiskExportManger is responsible on the export process of an image with a specific type (e.g template, file…)

src

Path to the image that should be exported

Type:str

name

The name of the exported disk

Type:str

dst

The absolute path of the exported disk

Type:str

disk_type

The type of the image e.g template, file, empty…

Type:str

disk

Disk attributes (of the disk that should be exported) as found in workdir/current/virt/VM-NAME

Type:dict

exported_metadata

A copy of the source disk metadata, this dict should be updated with new values during the export process.

Type:dict

do_compress

If true, apply compression to the exported disk.

Type:bool

_abc_cache = <_weakrefset.WeakSet object>

_abc_negative_cache = <_weakrefset.WeakSet object>

_abc_negative_cache_version = 43

_abc_registry = <_weakrefset.WeakSet object>

calc_sha(checksum)

Calculate the checksum of the new exported disk, write it to a file, and update this managers ‘exported_metadata’.

Parameters:checksum (str) – The type of the checksum

compress()

Compress the new exported image, Block size was taken from virt-builder page

copy()

Copy the disk using cp in order to preserves the ‘sparse’ structure of the file

export()

This method will handle the export process and should implemented in each subclass.

static get_instance_by_type(dst, disk, do_compress, *args, **kwargs)

Parameters:

• dst (str) – The path of the new exported disk. can contain env variables.
• disk (dict) – Disk attributes (of the disk that should be exported) as found in workdir/current/virt/VM-NAME
• do_compress (bool) – If true, apply compression to the exported disk.

Returns

An instance of a subclass of DiskExportManager which matches the disk type.

sparse()

Make the exported images more compact by removing unused space. Please refer to ‘virt-sparsify’ for more info.

update_lago_metadata()

write_lago_metadata()

class lago.export.FileExportManager(dst, disk_type, disk, do_compress, *args, **kwargs)

Bases: lago.export.DiskExportManager

FileExportManager is responsible exporting images of type file and empty.

standalone

If true, create a new image which is the result of merging all the layers of src (the image that we want to export).

Type:bool

src_qemu_info

Metadata on src which was generated by qemu-img.

Type:dict

_abc_cache = <_weakrefset.WeakSet object>

_abc_negative_cache = <_weakrefset.WeakSet object>

_abc_negative_cache_version = 43

_abc_registry = <_weakrefset.WeakSet object>

export()

See DiskExportManager.export

class lago.export.TemplateExportManager(dst, disk_type, disk, do_compress, *args, **kwargs)

Bases: lago.export.DiskExportManager

TemplateExportManager is responsible exporting images of type template.

See superclass

_abc_cache = <_weakrefset.WeakSet object>

_abc_negative_cache = <_weakrefset.WeakSet object>

_abc_negative_cache_version = 43

_abc_registry = <_weakrefset.WeakSet object>

export()

See DiskExportManager.export

rebase()

Change the backing-file entry of the exported disk. Please refer to ‘qemu-img rebase’ manual for more info.

update_lago_metadata()

class lago.export.VMExportManager(disks, dst, compress, with_threads=True, *args, **kwargs)

Bases: object

VMExportManager object is responsible on the export process of a list of disks.

disks

Disks to export.

Type:list of dicts

dst

Where to place the exported disks.

Type:str

compress

If True compress each exported disk.

Type:bool

with_threads

If True, run the export in parallel

Type:bool

*args

Extra args, will be passed to each DiskExportManager

Type:list

**kwargs

Extra args, will be passed to each DiskExportManager

Type:dict

_collect()

Returns:The disks that needed to be exported Return type:(generator of dicts)

_get_export_mgr()

Returns:Handler for each disk Return type:(DiskExportManager)

collect_paths()

Returns:The path of the disks that will be exported. Return type:(list of str)

export()

Run the export process :returns: The path of the exported disks. :rtype: (list of str)

exported_disks_paths()

Returns:The path of the exported disks. Return type:(list of str)

lago.guestfs_tools module

exception lago.guestfs_tools.GuestFSError

Bases: lago.utils.LagoException

lago.guestfs_tools._copy_path(conn, guest_path, host_path)

lago.guestfs_tools.extract_paths(disk_path, disk_root, paths, ignore_nopath)

Extract paths from a disk using guestfs

Parameters:

• disk_path (str) – path to the disk
• disk_root (str) – root partition
• paths (list of tuples) – files to extract in [(src1, dst1), (src2, dst2)…] format, if srcN is a directory in the guest, and dstN does not exist on the host, it will be created. If srcN is a file on the guest, it will be copied exactly to dstN
• ignore_nopath (bool) – If set to True, ignore paths in the guest that do not exit

Returns:

None

Raises:

• ExtractPathNoPathError – if a none existing path was found on the guest, and ignore_nopath is False.
• ExtractPathError – on all other failures.

lago.guestfs_tools.find_rootfs(conn, disk_root)

Find the image’s device root filesystem, and return its path.

1. Use guestfs.GuestFS.inspect_os() method. If it returns more than

   one root filesystem or None, try:

2. Find an exact match of disk_root from

   guestfs.GuestFS.list_filesystems(), if none is found, try:

3. Return the device that has the substring disk_root contained in it,

   from the output of guestfs.GuestFS.list_filesystems().

Parameters:

• conn (guestfs.GuestFS) – Open GuestFS handle.
• disk_root (str) – Root device to search for. Note that by default, if guestfs can deduce the filesystem, it will not be used.

Returns:

root device path

Return type:

str

Raises:

GuestFSError if no root filesystem was found

lago.guestfs_tools.guestfs_conn_mount_ro(*args, **kwds)

Open a GuestFS handle with disk_path and try mounting the root filesystem. disk_root is a hint where it should be looked and will only be used if GuestFS will not be able to deduce it independently.

Note that mounting a live guest, can lead to filesystem inconsistencies, causing the mount operation to fail. As we use readonly mode, this is safe, but the operation itself can still fail. Therefore, this method will watch for mount failures and retry 5 times before throwing an exception.

Parameters:

• disk_path (str) – Path to the disk.
• disk_root (str) – Hint what is the root device with the OS filesystem.
• retries (int) – Number of retries for mount_ro() operation. Note that on each retry a new GuestFS handle will be used.
• wait (int) – Time to wait between retries.

Yields:

guestfs.GuestFS – An open GuestFS handle.

Raises:

GuestFSError – On any guestfs operation error, including exceeding retries for the mount_ro() operation.

lago.guestfs_tools.guestfs_conn_ro(*args, **kwds)

Open a GuestFS handle and add disk in read only mode.

Parameters:disk (disk path) – Path to the disk. Yields:guestfs.GuestFS – Open GuestFS handle Raises:GuestFSError – On any guestfs operation failure

lago.lago_ansible module

class lago.lago_ansible.LagoAnsible(prefix)

Bases: object

A class for handling Ansible related tasks

prefix

The prefix that this object wraps

Type:lago.prefix.Prefix

_generate_entry(vm)

Generate host entry for the given VM :param vm: The VM for which the entry

should be created for.

Returns:An entry for vm Return type:str

get_inventory(keys=None)

Create an Ansible inventory based on python dicts and lists. The returned value is a dict in which every key represents a group and every value is a list of entries for that group.

Parameters:keys (list of str) – Path to the keys that will be used to create groups. Returns:dict based Ansible inventory Return type:dict

get_inventory_str(keys=None)

Convert a dict generated by ansible.LagoAnsible.get_inventory to an INI-like file.

Parameters:keys (list of str) – Path to the keys that will be used to create groups. Returns:INI-like Ansible inventory Return type:str

get_inventory_temp_file(**kwds)

Context manager which returns the inventory written on a tempfile. The tempfile will be deleted as soon as this context manger ends.

Parameters:keys (list of str) – Path to the keys that will be used to create groups. Yields:tempfile.NamedTemporaryFile – Temp file containing the inventory

static get_key(key, data_structure)

Helper method for extracting values from a nested data structure.

Parameters:

• key (str) – The path to the vales (a series of keys and indexes separated by ‘/’)
• data_structure (dict or list) – The data structure from which the value will be extracted.

Returns:

The values associated with key

Return type:

str

lago.log_utils module

lago.log_utils.ALWAYS_SHOW_REG = <_sre.SRE_Pattern object>

Regexp that will match the above template

lago.log_utils.ALWAYS_SHOW_TRIGGER_MSG = 'force-show:%s'

Message template that will always shoud the messago

class lago.log_utils.ColorFormatter(fmt=None, datefmt=None)

Bases: logging.Formatter

Formatter to add colors to log records

CRITICAL = '\x1b[31m'

CYAN = '\x1b[36m'

DEBUG = ''

DEFAULT = '\x1b[0m'

ERROR = '\x1b[31m'

GREEN = '\x1b[32m'

INFO = '\x1b[36m'

NONE = ''

RED = '\x1b[31m'

WARNING = '\x1b[33m'

WHITE = '\x1b[37m'

YELLOW = '\x1b[33m'

classmethod colored(color, message)

Small function to wrap a string around a color

Parameters:

• color (str) – name of the color to wrap the string with, must be one of the class properties
• message (str) – String to wrap with the color

Returns:

the colored string

Return type:

str

format(record)

Adds colors to a log record and formats it with the default

Parameters:record (logging.LogRecord) – log record to format Returns:The colored and formatted record string Return type:str

class lago.log_utils.ContextLock

Bases: object

Context manager to thread lock a block of code

lago.log_utils.END_TASK_MSG = 'Success'

Message to be shown when a task is ended

lago.log_utils.END_TASK_REG = <_sre.SRE_Pattern object>

Regexp that will match the above template

lago.log_utils.END_TASK_TRIGGER_MSG = 'end task%s'

Message template that will trigger a task end

class lago.log_utils.LogTask(task, logger=<module 'logging' from '/home/docs/.pyenv/versions/2.7.16/lib/python2.7/logging/__init__.pyc'>, level='info', propagate_fail=True, uuid=None)

Bases: object

Context manager for a log task

Example

>>> with LogTask('mytask'):
...     pass

lago.log_utils.START_TASK_MSG = ''

Message to be shown when a task is started

lago.log_utils.START_TASK_REG = <_sre.SRE_Pattern object>

Regexp that will match the above template

lago.log_utils.START_TASK_TRIGGER_MSG = 'start task%s'

Message template that will trigger a task

class lago.log_utils.Task(name, *args, **kwargs)

Bases: collections.deque

Small wrapper around deque to add the failed status and name to a task

name

name for this task

Type:str

failed

If this task has failed or not (if there was any error log shown during it’s execution)

Type:bool

force_show

If set, will show any log records generated inside this task even if it’s out of nested depth limit

Type:bool

elapsed_time()

class lago.log_utils.TaskHandler(initial_depth=0, task_tree_depth=-1, buffer_size=2000, dump_level=40, level=0, formatter=<class 'lago.log_utils.ColorFormatter'>)

Bases: logging.StreamHandler

This log handler will use the concept of tasks, to hide logs, and will show all the logs for the current task if there’s a logged error while running that task.

It will hide any logs that belong to nested tasks that have more than task_tree_depth parent levels, and for the ones that are above that level, it will show only the logs that have a loglevel above level.

You can force showing a log record immediately if you use the log_always() function bypassing all the filters.

If there’s a log record with log level higher than dump_level it will be considered a failure, and all the logs for the current task that have a log level above level will be shown no matter at which depth the task belongs to. Also, all the parent tasks will be tagged as error.

formatter

formatter to use

Type:logging.LogFormatter

initial_depth

Initial depth to account for, in case this handler was created in a subtask

Type:int

tasks_by_thread (dict of str

OrderedDict of str: Task): List of thread names, and their currently open tasks with their latest log records

dump_level

log level from which to consider a log record as error

Type:int

buffer_size

Size of the log record deque for each task, the bigger, the more records it can show in case of error but the more memory it will use

Type:int

task_tree_depth

number of the nested level to show start/end task logs for, if -1 will show always

Type:int

level

Log level to show logs from if the depth limit is not reached

Type:int

main_failed

used to flag from a child thread that the main should fail any current task

Type:bool

_tasks_lock

Lock for the tasks_by_thread dict

Type:ContextLock

_main_thread_lock

Lock for the main_failed bool

Type:ContextLock

TASK_INDICATORS = ['@', '#', '*', '-', '~']

List of chars to show as task prefix, to ease distinguishing them

am_i_main_thread

if the current thread is the main thread

Type:Returns Type:bool

close_children_tasks(parent_task_name)

Closes all the children tasks that were open

Parameters:parent_task_name (str) – Name of the parent task Returns:None

cur_depth_level

depth level for the current task

Type:Returns Type:int

cur_task

the current active task

Type:Returns Type:str

cur_thread

Name of the current thread

Type:Returns Type:str

emit(record)

Handle the given record, this is the entry point from the python logging facility

Params:

record (logging.LogRecord): log record to handle

Returns:None

get_task_indicator(task_level=None)

Parameters:task_level (int or None) – task depth level to get the indicator for, if None, will use the current tasks depth Returns:char to prepend to the task logs to indicate it’s level Return type:str

get_tasks(thread_name)

Parameters:thread_name (str) – name of the thread to get the tasks for Returns:

list of task names and log records for

each for the given thread

Return type:OrderedDict of str, Task

handle_closed_task(task_name, record)

Do everything needed when a task is closed

Params:

task_name (str): name of the task that is finishing record (logging.LogRecord): log record with all the info

Returns:None

handle_error()

Handles an error log record that should be shown

Returns:None

handle_new_task(task_name, record)

Do everything needed when a task is starting

Params:

task_name (str): name of the task that is starting record (logging.LogRecord): log record with all the info

Returns:None

mark_main_tasks_as_failed()

Flags to the main thread that all it’s tasks sholud fail

Returns:None

mark_parent_tasks_as_failed(task_name, flush_logs=False)

Marks all the parent tasks as failed

Parameters:

• task_name (str) – Name of the child task
• flush_logs (bool) – If True will discard all the logs form parent tasks

Returns:

None

pretty_emit(record, is_header=False, task_level=None)

Wrapper around the logging.StreamHandler emit method to add some decoration stuff to the message

Parameters:

• record (logging.LogRecord) – log record to emit
• is_header (bool) – if this record is a header, usually, a start or end task message
• task_level (int) – If passed, will take that as the current nested task level instead of calculating it from the current tasks

Returns:

None

should_show_by_depth(cur_level=None)

Parameters:cur_level (int) – depth level to take into account Returns:

True if the given depth level should show messages (not

taking into account the log level)

Return type:bool

should_show_by_level(record, base_level=None)

Parameters:

• record_level (int) – log level of the record to check
• base_level (int or None) – log level to check against, will use the object’s dump_level if None is passed

Returns:

True if the given log record should be shown according to the

log level

Return type:

bool

tasks

list of task names and log records for

each for the current thread

Type:Returns Type:OrderedDict of str, Task

lago.log_utils.end_log_task(task, logger=<module 'logging' from '/home/docs/.pyenv/versions/2.7.16/lib/python2.7/logging/__init__.pyc'>, level='info')

Ends a log task

Parameters:

• task (str) – name of the log task to end
• logger (logging.Logger) – logger to use
• level (str) – log level to use

Returns:

None

lago.log_utils.get_default_log_formatter()

lago.log_utils.hide_paramiko_logs()

lago.log_utils.hide_stevedore_logs()

Hides the logs of stevedore, this function was added in order to support older versions of stevedore

We are using the NullHandler in order to get rid from ‘No handlers could be found for logger…’ msg

Returns:None

lago.log_utils.log_always(message)

Wraps the given message with a tag that will make it be always logged by the task logger

Parameters:message (str) – message to wrap with the tag Returns:

tagged message that will get it shown immediately by the task

logger

Return type:str

lago.log_utils.log_task(task, logger=<module 'logging' from '/home/docs/.pyenv/versions/2.7.16/lib/python2.7/logging/__init__.pyc'>, level='info', propagate_fail=True, uuid=None)

Parameterized decorator to wrap a function in a log task

Example

>>> @log_task('mytask')
... def do_something():
...     pass

lago.log_utils.setup_prefix_logging(logdir)

Sets up a file logger that will create a log in the given logdir (usually a lago prefix)

Parameters:logdir (str) – path to create the log into, will be created if it does not exist Returns:None

lago.log_utils.start_log_task(task, logger=<module 'logging' from '/home/docs/.pyenv/versions/2.7.16/lib/python2.7/logging/__init__.pyc'>, level='info')

Starts a log task

Parameters:

• task (str) – name of the log task to start
• logger (logging.Logger) – logger to use
• level (str) – log level to use

Returns:

None

lago.paths module

class lago.paths.Paths(prefix_path)

Bases: object

A Paths object contains methods for getting the paths to the directories and files which composes the prefix.

_prefix_path

Path to the directory of the prefix

Type:str

images(*path)

logs()

metadata()

prefix_lagofile()

This file represents a prefix that’s initialized

prefix_path()

prefixed(*args)

scripts(*args)

ssh_id_rsa()

ssh_id_rsa_pub()

uuid()

virt(*path)

lago.prefix module

exception lago.prefix.LagoDeployError

Bases: lago.utils.LagoException

class lago.prefix.Prefix(prefix)

Bases: object

A prefix is a directory that will contain all the data needed to setup the environment.

_paths

Paths handler class

Type:lago.path.Paths

_virt_env

Lazily loaded virtual env handler

Type:lago.virt.VirtEnv

_metadata

Lazily loaded metadata

Type:dict

VIRT_ENV_CLASS

alias of lago.virt.VirtEnv

_add_dns_records(conf, mgmts)

Add DNS records dict(‘dns_records’) to conf for each management network. Add DNS forwarder IP(‘dns_forward’) for each none management network.

Parameters:

• conf (spec) – spec
• mgmts (list) – management networks names

Returns:

None

_add_mgmt_to_domains(conf, mgmts)

Add management network key(‘mgmt_net’) to each domain. Note this assumes conf was validated.

Parameters:

• conf (dict) – spec
• mgmts (list) – list of management networks names

_add_nic_to_mapping(net, dom, nic)

Populates the given net spec mapping entry with the nics of the given domain, by the following rules:

• If net is management, ‘domain_name’: nic_ip
• For each interface: ‘domain_name-eth#’: nic_ip, where # is the

index of the nic in the domain definition. * For each interface: ‘domain_name-net_name-#’: nic_ip, where # is a running number of interfaces from that network. * For each interface: ‘domain_name-net_name’, which has an identical IP to ‘domain_name-net_name-0’

Parameters:

• net (dict) – Network spec to populate
• dom (dict) – libvirt domain specification
• nic (str) – Name of the interface to add to the net mapping from the domain

Returns:

None

_allocate_ips_to_nics(conf)

For all the nics of all the domains in the conf that have dynamic ip, allocate one and addit to the network mapping

Parameters:conf (dict) – Configuration spec to extract the domains from Returns:None

_allocate_subnets(conf)

Allocate all the subnets needed by the given configuration spec

Parameters:conf (dict) – Configuration spec where to get the nets definitions from Returns:allocated subnets and modified conf Return type:tuple(list, dict)

_config_net_topology(conf)

Initialize and populate all the network related elements, like reserving ips and populating network specs of the given confiiguration spec

Parameters:conf (dict) – Configuration spec to initalize Returns:None

_copy_delpoy_scripts(scripts)

Copy the given deploy scripts to the scripts dir in the prefix

Parameters:scripts (list of str) – list of paths of the scripts to copy to the prefix Returns:

list with the paths to the copied scripts, with a

prefixed with $LAGO_PREFIX_PATH so the full path is not hardcoded

Return type:list of str

_copy_deploy_scripts_for_hosts(domains)

Copy the deploy scripts for all the domains into the prefix scripts dir

Parameters:domains (dict) – spec with the domains info as when loaded from the initfile Returns:None

_create_disk(name, spec, template_repo=None, template_store=None)

Creates a disc with the given name from the given repo or store

Parameters:

• name (str) – Name of the domain to create the disk for
• spec (dict) – Specification of the disk to create
• template_repo (TemplateRepository or None) – template repo instance to use
• template_store (TemplateStore or None) – template store instance to use

Returns:

Path to the disk and disk metadata

Return type:

Tuple(str, dict)

Raises:

RuntimeError – If the type of the disk is not supported or failed to create the disk

_create_disks(domain_name, disks_specs, template_repo, template_store)

_create_link_to_parent(base, link_name)

_create_ssh_keys()

Generate a pair of ssh keys for this prefix

Returns:None Raises:RuntimeError – if it fails to create the keys

_create_virt_env()

Create a new virt env from this prefix

Returns:virt env created from this prefix Return type:lago.virt.VirtEnv

_deploy_host(host)

static _generate_disk_name(host_name, disk_name, disk_format)

_generate_disk_path(disk_name)

_get_net(conf, dom_name, nic)

_get_scripts(host_metadata)

Temporary method to retrieve the host scripts

Parameters:host_metadata (dict) – host metadata to retrieve the scripts for Returns:deploy scripts for the host, empty if none found Return type:list

_handle_empty_disk(host_name, disk_spec)

_handle_file_disk(disk_spec)

_handle_lago_template(disk_path, template_spec, template_store, template_repo)

_handle_ova_image(domain_spec)

_handle_qcow_template(disk_path, template_spec, template_store=None, template_repo=None)

_handle_template(host_name, template_spec, template_store=None, template_repo=None)

static _init_net_specs(conf)

Given a configuration specification, initializes all the net definitions in it so they can be used comfortably

Parameters:conf (dict) – Configuration specification Returns:the adapted new conf Return type:dict

_ova_to_spec(filename)

Retrieve the given ova and makes a template of it. Creates a disk from network provided ova. Calculates the needed memory from the ovf. The disk will be cached in the template repo

Parameters:filename (str) – the url to retrive the data from

Returns:

list with the disk specification int: VM memory, None if none defined int: Number of virtual cpus, None if none defined

Return type:

list of dict

Raises:

• RuntimeError – If the ova format is not supported
• TypeError – If the memory units in the ova are noot supported (currently only ‘MegaBytes’)

_prepare_domain_image(domain_spec, prototypes, template_repo, template_store)

_prepare_domains_images(conf, template_repo, template_store)

_register_preallocated_ips(conf)

Parse all the domains in the given conf and preallocate all their ips into the networks mappings, raising exception on duplicated ips or ips out of the allowed ranges

See also

lago.subnet_lease

Parameters:conf (dict) – Configuration spec to parse Returns:None Raises:RuntimeError – if there are any duplicated ips or any ip out of the allowed range

_retrieve_disk_url(disk_url, disk_dst_path=None)

static _run_qemu(qemu_cmd, disk_path)

_save_metadata()

Write this prefix metadata to disk

Returns:None

_select_mgmt_networks(conf)

Select management networks. If no management network is found, it will mark the first network found by sorted the network lists. Also adding default DNS domain, if none is set.

Parameters:conf (spec) – spec

_set_mtu_to_nics(conf)

For all the nics of all the domains in the conf that have MTU set, save the MTU on the NIC definition.

Parameters:conf (dict) – Configuration spec to extract the domains from Returns:None

_set_scripts(host_metadata, scripts)

Temporary method to set the host scripts

Parameters:host_metadata (dict) – host metadata to set scripts in Returns:the updated metadata Return type:dict

_use_prototype(spec, prototypes)

Populates the given spec with the values of it’s declared prototype

Parameters:

• spec (dict) – spec to update
• prototypes (dict) – Configuration spec containing the prototypes

Returns:

updated spec

Return type:

dict

_validate_netconfig(conf)

Validate network configuration

Parameters:

conf (dict) – spec

Returns:

None

Raises:

• LagoInitException – If a VM has more than
• one management network configured, or a network which is not
• management has DNS attributes, or a VM is configured with a
• none-existence NIC, or a VM has no management network.

build(conf)

cleanup(**kwargs)

Stops any running entities in the prefix and uninitializes it, usually you want to do this if you are going to remove the prefix afterwards

Returns:None

collect_artifacts(**kwargs)

create_snapshots(name)

Creates one snapshot on all the domains with the given name

Parameters:name (str) – Name of the snapshots to create Returns:None

deploy(**kwargs)

destroy()

Destroy this prefix, running any cleanups and removing any files inside it.

export_vms(**kwargs)

Export vm images disks and init file. The exported images and init file can be used to recreate the environment.

Parameters:

• vms_names (list of str) – Names of the vms to export, if None export all the vms in the env (default=None)
• standalone (bool) – If false, export a layered image (default=False)
• export_dir (str) – Dir to place the exported images and init file
• compress (bool) – If True compress the images with xz (default=False)
• init_file_name (str) – The name of the exported init file (default=’LagoInitfile’)
• out_format (lago.plugins.output.OutFormatPlugin) – The type of the exported init file (the default is yaml)
• collect_only (bool) – If True, return only a mapping from vm name to the disks that will be exported. (default=False)
• with_threads (bool) – If True, run the export in parallel (default=True)

Returns

Unless collect_only == True, a mapping between vms’ disks.

fetch_url(url)

Retrieves the given url to the prefix

Parameters:url (str) – Url to retrieve Returns:path to the downloaded file Return type:str

get_nets(**kwargs)

Retrieve info on all the nets from all the domains

Returns:dictionary with net_name -> net list Return type:dict of str->list(str)

get_paths(**kwargs)

Get the Paths object of this prefix. The Paths object contains the paths to the internal directories and files of this prefix.

Returns:The Paths object of this prefix Return type:lago.paths.Paths

get_snapshots()

Retrieve info on all the snapshots from all the domains

Returns:list(str): dictionary with vm_name -> snapshot list Return type:dict of str

get_vms(**kwargs)

Retrieve info on all the vms

Returns:dictionary with vm_name -> vm list Return type:dict of str->list(str)

initialize(**kwargs)

Initialize this prefix, this includes creating the destination path, and creating the uuid for the prefix, for any other actions see Prefix.virt_conf()

Will safely roll back if any of those steps fail

Returns:None Raises:RuntimeError – If it fails to create the prefix dir

classmethod is_prefix(path)

Check if a path is a valid prefix

Parameters:path (str) – path to be checked Returns:True if the given path is a prefix Return type:bool

metadata

Retrieve the metadata info for this prefix

Returns:metadata info Return type:dict

paths

resolve_parent(disk_path, template_store, template_repo)

Given a virtual disk, checks if it has a backing file, if so check if the backing file is in the store, if not download it from the provided template_repo.

After verifying that the backing-file is in the store, create a symlink to that file and locate it near the layered image.

Parameters:

• disk_path (str) – path to the layered disk
• template_repo (TemplateRepository or None) – template repo instance to use
• template_store (TemplateStore or None) – template store instance to use

classmethod resolve_prefix_path(start_path=None)

Look for an existing prefix in the given path, in a path/.lago dir, or in a .lago dir under any of it’s parent directories

Parameters:start_path (str) – path to start the search from, if None passed, it will use the current dir Returns:path to the found prefix Return type:str Raises:RuntimeError – if no prefix was found

revert_snapshots(name)

Revert all the snapshots with the given name from all the domains

Parameters:name (str) – Name of the snapshots to revert Returns:None

save()

Save this prefix to persistent storage

Returns:None

shutdown(**kwargs)

Shutdown this prefix

Parameters:

• vm_names (list of str) – List of the vms to shutdown
• reboot (bool) – If true, reboot the requested vms

Returns:

None

start(**kwargs)

Start this prefix

Parameters:vm_names (list of str) – List of the vms to start Returns:None

stop(**kwargs)

Stop this prefix

Parameters:vm_names (list of str) – List of the vms to stop Returns:None

virt_conf(conf, template_repo=None, template_store=None, do_bootstrap=True, do_build=True)

Initializes all the virt infrastructure of the prefix, creating the domains disks, doing any network leases and creating all the virt related files and dirs inside this prefix.

Parameters:

• conf (dict) – Configuration spec
• template_repo (TemplateRepository) – template repository intance
• template_store (TemplateStore) – template store instance
• do_bootstrap (bool) – If true run virt-sysprep on the images
• do_build (bool) – If true run build commands on the images, see lago.build.py for more info.

Returns:

None

virt_conf_from_stream(conf_fd, template_repo=None, template_store=None, do_bootstrap=True, do_build=True)

Initializes all the virt infrastructure of the prefix, creating the domains disks, doing any network leases and creating all the virt related files and dirs inside this prefix.

Parameters:

• conf_fd (File) – File like object to read the config from
• template_repo (TemplateRepository) – template repository intance
• template_store (TemplateStore) – template store instance

Returns:

None

virt_env

Getter for this instance’s virt env, creates it if needed

Returns:virt env instance used by this prefix Return type:lago.virt.VirtEnv

lago.prefix._create_ip(subnet, index)

Given a subnet or an ip and an index returns the ip with that lower index from the subnet (255.255.255.0 mask only subnets)

Parameters:

• subnet (str) – Strign containing the three first elements of the decimal representation of a subnet (X.Y.Z) or a full ip (X.Y.Z.A)
• index (int or str) – Last element of a decimal ip representation, for example, 123 for the ip 1.2.3.123

Returns:

The dotted decimal representation of the ip

Return type:

str

lago.prefix._ip_in_subnet(subnet, ip)

Checks if an ip is included in a subnet.

Note

only 255.255.255.0 masks allowed

Parameters:

• subnet (str) – Strign containing the three first elements of the decimal representation of a subnet (X.Y.Z) or a full ip (X.Y.Z.A)
• ip (str or int) – Decimal ip representation

Returns:

True if ip is in subnet, False otherwise

Return type:

bool

lago.prefix.log_task(task, level='info', propagate_fail=True, uuid=None)

Parameterized decorator to wrap a function in a log task

Example

>>> @log_task('mytask')
... def do_something():
...     pass

lago.sdk module

class lago.sdk.SDK(workdir, prefix)

Bases: object

The SDK can be initialized in 3 ways:

1. (Preferred) - by calling sdk.init().

2. By loading an existing workdir from the disk, with

   load_env().

3. By passing already created workdir and prefix objects.

ansible_inventory(keys=['vm-type', 'groups', 'vm-provider'])

Get an Ansible inventory as a string, keys should be list on which to group the hosts by. You can use any key defined in LagoInitFile.

Examples of possible keys:

keys=[‘disks/0/metadata/arch’], would group the hosts by the architecture.

keys=[‘/disks/0/metadata/distro’, ‘disks/0/metadata/arch’],

would create groups by architecture and also by distro.

keys=[‘groups’] - would group hosts by the groups defined for

each VM in the LagoInitFile, i.e.:

domains:

vm-01:

… groups: web-server ..

vm-02:

groups: db-server

Parameters:keys (list of str) – Path to the keys that will be used to create groups. Returns:INI-like Ansible inventory Return type:str

ansible_inventory_temp_file(keys=['vm-type', 'groups', 'vm-provider'])

Context manager which returns Ansible inventory written on a tempfile. This is the same as ansible_inventory(), only the inventory file is written to a tempfile.

Parameters:keys (list of str) – Path to the keys that will be used to create groups. Yields:tempfile.NamedTemporaryFile – Temp file containing the inventory

destroy()

Destroy the environment, this will terminate all resources, and remove entirely the Lago working directory.

lago.sdk.add_stream_logger(level=10, name=None)

Add a stream logger. This can be used for printing all SDK calls to stdout while working in an interactive session. Note this is a logger for the entire module, which will apply to all environments started in the same session. If you need a specific logger pass a logfile to init()

Parameters:

• level (int) – logging log level
• name (str) – logger name, will default to the root logger.

Returns:

None

lago.sdk.init(config, workdir=None, logfile=None, loglevel=20, **kwargs)

Initialize the Lago environment

Parameters:

• config (str) – Path to LagoInitFile
• workdir (str) – Path to initalize the workdir, defaults to “$PWD/.lago”
• **kwargs (dict) – Pass arguments to do_init()
• logfile (str) – A path to setup a log file.
• loglevel (int) – logging log level.

Returns:

Initialized Lago enviornment

Return type:

SDK

Raises:

LagoException – If initialization failed

lago.sdk.load_env(workdir, logfile=None, loglevel=20)

Load an existing Lago environment

Parameters:workdir (str) – Path to the workdir directory, as created by

:param init() or created by the CLI.: :param logfile: A Path to setup a log file. :type logfile: str :param loglevel: logging log level. :type loglevel: int

Returns:Initialized Lago environment Return type:SDK Raises:LagoException – If loading the environment failed.

lago.sdk_utils module

class lago.sdk_utils.SDKMethod(name)

Bases: object

Metadata to store inside the decorated function

class lago.sdk_utils.SDKWrapper(*args, **kwargs)

Bases: sphinx.ext.autodoc.importer._MockObject

A proxy object that exposes only methods which were decorated with expose() decorator.

lago.sdk_utils.expose(func)

Decorator to be used with SDKWrapper. This decorator indicates that the wrapped method or class should be exposed in the proxied object.

Parameters:func (types.FunctionType/types.MethodType) – function to decorate Returns:None

lago.sdk_utils.getattr_sdk(attr, name)

Filter SDK attributes

Parameters:

• attr (attribute) – Attribute as returned by getattr().
• name (str) – Attribute name.

Returns:

attr if passed.

lago.sdk_utils.setup_sdk_logging(logfile=None, loglevel=20)

Setup a NullHandler to the root logger. If logfile is passed, additionally add a FileHandler in loglevel level.

Parameters:

• logfile (str) – A path to setup a log file.
• loglevel (int) – logging log level.

Returns:

None

lago.service module

class lago.service.SysVInitService(vm, name)

Bases: lago.plugins.service.ServicePlugin

BIN_PATH = '/sbin/service'

_abc_cache = <_weakrefset.WeakSet object>

_abc_negative_cache = <_weakrefset.WeakSet object>

_abc_negative_cache_version = 43

_abc_registry = <_weakrefset.WeakSet object>

_request_start()

Low level implementation of the service start request, used by the func:start method

Returns:True if the service succeeded to start, False otherwise Return type:bool

_request_stop()

Low level implementation of the service stop request, used by the func:stop method

Returns:True if the service succeeded to stop, False otherwise Return type:bool

state()

Check the current status of the service

Returns:Which state the service is at right now Return type:ServiceState

class lago.service.SystemdContainerService(vm, name)

Bases: lago.plugins.service.ServicePlugin

BIN_PATH = '/usr/bin/docker'

HOST_BIN_PATH = '/usr/bin/systemctl'

_abc_cache = <_weakrefset.WeakSet object>

_abc_negative_cache = <_weakrefset.WeakSet object>

_abc_negative_cache_version = 43

_abc_registry = <_weakrefset.WeakSet object>

_request_start()

Low level implementation of the service start request, used by the func:start method

Returns:True if the service succeeded to start, False otherwise Return type:bool

_request_stop()

Low level implementation of the service stop request, used by the func:stop method

Returns:True if the service succeeded to stop, False otherwise Return type:bool

state()

Check the current status of the service

Returns:Which state the service is at right now Return type:ServiceState

class lago.service.SystemdService(vm, name)

Bases: lago.plugins.service.ServicePlugin

BIN_PATH = '/usr/bin/systemctl'

_abc_cache = <_weakrefset.WeakSet object>

_abc_negative_cache = <_weakrefset.WeakSet object>

_abc_negative_cache_version = 43

_abc_registry = <_weakrefset.WeakSet object>

_request_start()

Low level implementation of the service start request, used by the func:start method

Returns:True if the service succeeded to start, False otherwise Return type:bool

_request_stop()

Low level implementation of the service stop request, used by the func:stop method

Returns:True if the service succeeded to stop, False otherwise Return type:bool

state()

Check the current status of the service

Returns:Which state the service is at right now Return type:ServiceState

lago.ssh module

exception lago.ssh.LagoSSHTimeoutException

Bases: lago.utils.LagoException

lago.ssh._gen_ssh_command_id()

lago.ssh.drain_ssh_channel(chan, stdin=None, stdout=<open file '<stdout>', mode 'w'>, stderr=<open file '<stderr>', mode 'w'>)

lago.ssh.get_ssh_client(ip_addr, ssh_key=None, host_name=None, ssh_tries=None, propagate_fail=True, username='root', password='123456')

Get a connected SSH client

Parameters:

• ip_addr (str) – IP address of the endpoint
• ssh_key (str or list of str) – Path to a file which contains the private key
• hotname (str) – The hostname of the endpoint
• ssh_tries (int) – The number of attempts to connect to the endpoint
• propagate_fail (bool) – If set to true, this event will be in the log and fail the outer stage. Otherwise, it will be discarded.
• username (str) – The username to authenticate with
• password (str) – Used for password authentication or for private key decryption

Raises:

LagoSSHTimeoutException – If the client failed to connect after “ssh_tries”

lago.ssh.interactive_ssh(ip_addr, command=None, host_name=None, ssh_key=None, username='root', password='123456')

lago.ssh.interactive_ssh_channel(chan, command=None, stdin=<open file '<stdin>', mode 'r'>)

lago.ssh.log_task(task, level='info', propagate_fail=True, uuid=None)

Parameterized decorator to wrap a function in a log task

Example

>>> @log_task('mytask')
... def do_something():
...     pass

lago.ssh.ssh(ip_addr, command, host_name=None, data=None, show_output=True, propagate_fail=True, tries=None, ssh_key=None, username='root', password='123456')

lago.ssh.ssh_script(ip_addr, path, host_name=None, show_output=True, ssh_key=None, username='root', password='123456')

lago.ssh.wait_for_ssh(ip_addr, host_name=None, connect_timeout=600, ssh_key=None, username='root', password='123456')

lago.subnet_lease module

exception lago.subnet_lease.LagoSubnetLeaseBadPermissionsException(store_path, prv_msg)

Bases: lago.subnet_lease.LagoSubnetLeaseException

exception lago.subnet_lease.LagoSubnetLeaseException(msg, prv_msg=None)

Bases: lago.utils.LagoException

exception lago.subnet_lease.LagoSubnetLeaseLockException(store_path)

Bases: lago.subnet_lease.LagoSubnetLeaseException

exception lago.subnet_lease.LagoSubnetLeaseMalformedAddrException(required_subnet)

Bases: lago.subnet_lease.LagoSubnetLeaseException

exception lago.subnet_lease.LagoSubnetLeaseOutOfRangeException(required_subnet, store_range)

Bases: lago.subnet_lease.LagoSubnetLeaseException

exception lago.subnet_lease.LagoSubnetLeaseStoreFullException(store_range)

Bases: lago.subnet_lease.LagoSubnetLeaseException

exception lago.subnet_lease.LagoSubnetLeaseTakenException(required_subnet, lease_taken_by)

Bases: lago.subnet_lease.LagoSubnetLeaseException

class lago.subnet_lease.Lease(store_path, subnet)

Bases: object

Lease object is an abstraction of a lease file.

_store_path

Path to the lease’s store.

Type:str

_subnet

The subnet that this lease represents

Type:str

_path

The path to the lease file

Type:str

_has_env(uuid_path=None, uuid=None)

_realise_lease_path()

exist

has_env

metadata

path

subnet

to_ip_network()

uuid

uuid_path

valid

class lago.subnet_lease.SubnetStore(path=None, min_third_octet=200, max_third_octet=255)

Bases: object

SubnetStore object represents a store of subnets used by lago for network bridges.

Note

Currently only /24 ranges are handled, and all of them under the 192.168._min_third_octet to 192.168._max_third_octet ranges.

The leases are stored under the store’s directory (which is specified with the path argument) as json files with the form:

[
    "/path/to/prefix/uuid/file",
    "uuid_hash",
]

Where the uuid_hash is the 32 char uuid of the prefix (the contents of the uuid file at the time of doing the lease).

The helper class Lease is used to abstract the interaction with the lease files in the store (each file will be represented with a Lease object).

Cleanup of stale leases is done in a lazy manner during a request for a lease. The store will remove at most 1 stale lease in each request (see SubnetStore._lease_valid for more info).

_path

Path to the store, if not specified defaults to the value of lease_dir in the config

Type:str

_cidr

Number of bits dedicated for the network address. Has a fixed value of 24.

Type:int

_subnet_template

A template for creating ip address. Has a fixed value of 192.168.{}.0

Type:str

_min_third_octet

The minimum value of the subnets’ last octet.

Type:int

_max_third_octet

The maximum value of the subnets’ last octet.

Type:int

_min_subnet

The lowest subnet in the range of the store.

Type:netaddr.IPNetwork

_max_subnet

The highest subnet in the range of the store.

Type:netaddr.IPNetwork

_acquire(uuid_path)

Lease a free network for the given uuid path

Parameters:uuid_path (str) – Path to the uuid file of a lago.Prefix Returns:Which represents the selected subnet Return type:netaddr.IPNetwork Raises:LagoSubnetLeaseException – If the store is full

_acquire_given_subnet(uuid_path, subnet)

Try to create a lease for subnet

Parameters:

• uuid_path (str) – Path to the uuid file of a lago.Prefix
• subnet (str) – dotted ipv4 subnet (for example `192.168.200.0`)

Returns:

Which represents the selected subnet

Return type:

netaddr.IPNetwork

Raises:

LagoSubnetLeaseException – If the requested subnet is not in the range of this store or its already been taken

_create_lock()

_lease_owned(lease, current_uuid_path)

Checks if the given lease is owned by the prefix whose uuid is in the given path

Note

The prefix must be also in the same path it was when it took the lease

Parameters:

• path (str) – Path to the lease
• current_uuid_path (str) – Path to the uuid to check ownership of

Returns:

True if the given lease in owned by the prefix,

False otherwise

Return type:

bool

_lease_valid(lease)

Check if the given lease exist and still has a prefix that owns it. If the lease exist but its prefix isn’t, remove the lease from this store.

Parameters:lease (lago.subnet_lease.Lease) – Object representation of the lease Returns:

If the lease and its prefix exists, return the path

to the uuid of the prefix, else return None.

Return type:str or None

_release(lease)

Free the given lease

Parameters:lease (lago.subnet_lease.Lease) – The lease to free

_take_lease(lease, uuid_path, safe=True)

Persist the given lease to the store and make the prefix in uuid_path his owner

Parameters:

• lease (lago.subnet_lease.Lease) – Object representation of the lease
• uuid_path (str) – Path to the prefix uuid
• safe (bool) – If true (the default), validate the the lease isn’t taken.

Raises:

LagoSubnetLeaseException – If safe == True and the lease is already taken.

_validate_lease_dir()

Validate that the directory used by this store exist,

otherwise create it.

acquire(uuid_path, subnet=None)

Lease a free subnet for the given uuid path. If subnet is given, try to lease that subnet, otherwise try to lease a free subnet.

Parameters:

• uuid_path (str) – Path to the uuid file of a lago.Prefix
• subnet (str) – A subnet to lease.

Returns:

An object which represents the subnet.

Return type:

netaddr.IPAddress

Raises:

• LagoSubnetLeaseException – 1. If this store is full 2. If the requested subnet is already taken.
• LagoSubnetLeaseLockException – If the lock to self.path can’t be acquired.

create_lease_object_from_idx(idx)

Create a lease from self._subnet_template and put idx as its third octet.

Parameters:

idx (str) – The value of the third octet

Returns:

Lease object which represents the requested subnet.

Return type:

Lease

Raises:

• LagoSubnetLeaseOutOfRangeException – If the resultant subnet is
• malformed or out of the range of the store.

create_lease_object_from_subnet(subnet)

Create a lease from ip in a dotted decimal format, (for example 192.168.200.0/24). the _cidr will be added if not exist in subnet.

Parameters:

subnet (str) – The value of the third octet

Returns:

Lease object which represents the requested subnet.

Return type:

Lease

Raises:

• LagoSubnetLeaseOutOfRangeException – If the resultant subnet is
• malformed or out of the range of the store.

get_allowed_range()

Returns:

The range of the store (with lowest and highest subnets as

the bounds).

Return type:str

is_leasable_subnet(subnet)

Checks if a given subnet is inside the defined provision-able range

Parameters:subnet (str) – Ip in dotted decimal format with _cidr notation (for example 192.168.200.0/24) Returns:

True if subnet can be parsed into IPNetwork object and is

inside the range, False otherwise

Return type:bool Raises:netaddr.AddrFormatError – If subnet can not be parsed into an ip.

list_leases(uuid=None)

List current subnet leases

Parameters:uuid (str) – Filter the leases by uuid Returns:class:~Lease: current leases Return type:list of

path

release(subnets)

Free the lease of the given subnets

Parameters:

subnets (list of str or netaddr.IPAddress) – dotted ipv4 subnet in CIDR notation (for example `192.168.200.0/24`) or IPAddress object.

Raises:

• LagoSubnetLeaseException – If subnet is a str and can’t be parsed
• LagoSubnetLeaseLockException – If the lock to self.path can’t be acquired.

lago.sysprep module

lago.sysprep._guestfs_version()

lago.sysprep._render_template(distro, loader, **kwargs)

lago.sysprep.sysprep(disk, distro, loader=None, backend='direct', **kwargs)

Run virt-sysprep on the disk, commands are built from the distro specific template and arguments passed in kwargs. If no template is available it will default to sysprep-base.j2.

Parameters:

• disk (str) – path to disk
• distro (str) – distro to render template for
• loader (jinja2.BaseLoader) – Jinja2 template loader, if not passed, will search Lago’s package.
• backend (str) – libguestfs backend to use
• **kwargs (dict) – environment variables for Jinja2 template

Returns:

None

Raises:

RuntimeError – On virt-sysprep none 0 exit code.

lago.templates module

class lago.templates.FileSystemTemplateProvider(root)

Handles file type templates, that is, getting a disk template from the host’s filesystem

_prefixed(*path)

Join all the given paths prefixed with this provider’s base root path

Parameters:*path (str) – sections of the path to join, passed as positional arguments Returns:Joined paths prepended with the provider root path Return type:str

download_image(handle, dest)

Copies over the handl to the destination

Parameters:

• handle (str) – path to copy over
• dest (str) – path to copy to

Returns:

None

get_hash(handle)

Returns the associated hash for the given handle, the hash file must exist (handle + '.hash').

Parameters:handle (str) – Path to the template to get the hash from Returns:Hash for the given handle Return type:str

get_metadata(handle)

Returns the associated metadata info for the given handle, the metadata file must exist (handle + '.metadata').

Parameters:handle (str) – Path to the template to get the metadata from Returns:Metadata for the given handle Return type:dict

class lago.templates.HttpTemplateProvider(baseurl)

This provider allows the usage of http urls for templates

download_image(handle, dest)

Downloads the image from the http server

Parameters:

• handle (str) – url from the self.baseurl to the remote template
• dest (str) – Path to store the downloaded url to, must be a file path

Returns:

None

static extract_image_xz(path)

get_hash(handle)

Get the associated hash for the given handle, the hash file must exist (handle + '.hash').

Parameters:handle (str) – Path to the template to get the hash from Returns:Hash for the given handle Return type:str

get_metadata(handle)

Returns the associated metadata info for the given handle, the metadata file must exist (handle + '.metadata'). If the given handle has an .xz extension, it will get removed when calculating the handle metadata path

Parameters:handle (str) – Path to the template to get the metadata from Returns:Metadata for the given handle Return type:dict

open_url(url, suffix='', dest=None)

Opens the given url, trying the compressed version first. The compressed version url is generated adding the .xz extension to the url and adding the given suffix after that .xz extension. If dest passed, it will download the data to that path if able

Parameters:

• url (str) – relative url from the self.baseurl to retrieve
• suffix (str) – optional suffix to append to the url after adding the compressed extension to the path
• dest (str or None) – Path to save the data to

Returns:

response object to read from (lazy read), closed

if no dest passed

Return type:

urllib.addinfourl

Raises:

RuntimeError – if the url gave http error when retrieving it

exception lago.templates.LagoMissingTemplateError(name, path)

Bases: lago.utils.LagoException

class lago.templates.Template(name, versions)

Disk image template class

name

Name of this template

Type:str

_versions (dict(str

TemplateVersion)): versions for this template

get_latest_version()

Retrieves the latest version for this template, the latest being the one with the newest timestamp

Returns:TemplateVersion

get_version(ver_name=None)

Get the given version for this template, or the latest

Parameters:ver_name (str or None) – Version to retieve, None for the latest Returns:

The version matching the given name or the latest

one

Return type:TemplateVersion

class lago.templates.TemplateRepository(dom, path)

A template repository is a single source for templates, that uses different providers to actually retrieve them. That means for example that the ‘ovirt’ template repository, could support the ‘http’ and a theoretical ‘gluster’ template providers.

_dom

Specification of the template

Type:dict

_providers

Providers instances for any source in the spec

Type:dict

_get_provider(spec)

Get the provider for the given template spec

Parameters:spec (dict) – Template spec Returns:A provider instance for that spec Return type:HttpTemplateProvider or FileSystemTemplateProvider

classmethod from_url(path)

Instantiate a TemplateRepository instance from the data in a file or url

Parameters:path (str) – Path or url to the json file to load Returns:A new instance Return type:TemplateRepository

get_by_name(name)

Retrieve a template by it’s name

Parameters:name (str) – Name of the template to retrieve Raises:LagoMissingTemplateError – if no template is found

name

Getter for the template repo name

Returns:the name of this template repo Return type:str

path

Getter for the template repo path

Returns:the path/url of this template repo Return type:str

class lago.templates.TemplateStore(path)

Local cache to store templates

The store uses various files to keep track of the templates cached, access and versions. An example template store looks like:

$ tree /var/lib/lago/store/
/var/lib/lago/store/
├── in_office_repo:centos6_engine:v2.tmp
├── in_office_repo:centos7_engine:v5.tmp
├── in_office_repo:fedora22_host:v2.tmp
├── phx_repo:centos6_engine:v2
├── phx_repo:centos6_engine:v2.hash
├── phx_repo:centos6_engine:v2.metadata
├── phx_repo:centos6_engine:v2.users
├── phx_repo:centos7_engine:v4.tmp
├── phx_repo:centos7_host:v4.tmp
└── phx_repo:storage-nfs:v1.tmp

There you can see the files:

• *.tmp

  Temporary file created while downloading the template from the repository (depends on the provider)

• ${repo_name}:${template_name}:${template_version}

  This file is the actual disk image template

• *.hash

  Cached hash for the template disk image

• *.metadata

  Metadata for this template image in json format, usually this includes the distro and root-password

__contains__(temp_ver)

Checks if a given version is in this store

Parameters:temp_ver (TemplateVersion) – Version to look for Returns:True if the version is in this store Return type:bool

_prefixed(*path)

Join the given paths and prepend this stores path

Parameters:*path (str) – list of paths to join, as positional arguments Returns:all the paths joined and prepended with the store path Return type:str

download(temp_ver, store_metadata=True)

Retrieve the given template version

Parameters:

• temp_ver (TemplateVersion) – template version to retrieve
• store_metadata (bool) – If set to False, will not refresh the local metadata with the retrieved one

Returns:

None

get_path(temp_ver)

Get the path of the given version in this store

Parameters:TemplateVersion (temp_ver) – version to look for Returns:The path to the template version inside the store Return type:str Raises:RuntimeError – if the template is not in the store

get_stored_hash(temp_ver)

Retrieves the hash for the given template version from the store

Parameters:temp_ver (TemplateVersion) – template version to retrieve the hash for Returns:hash of the given template version Return type:str

get_stored_metadata(temp_ver)

Retrieves the metadata for the given template version from the store

Parameters:temp_ver (TemplateVersion) – template version to retrieve the metadata for Returns:the metadata of the given template version Return type:dict

class lago.templates.TemplateVersion(name, source, handle, timestamp)

Each template can have multiple versions, each of those is actually a different disk template file representation, under the same base name.

download(destination)

Retrieves this template to the destination file

Parameters:destination (str) – file path to write this template to Returns:None

get_hash()

Returns the associated hash for this template version

Returns:Hash for this version Return type:str

get_metadata()

Returns the associated metadata info for this template version

Returns:Metadata for this version Return type:dict

timestamp()

Getter for the timestamp

lago.templates._PROVIDERS = {'file': <class lago.templates.FileSystemTemplateProvider>, 'http': <class lago.templates.HttpTemplateProvider>}

Registry for template providers

lago.templates.find_repo_by_name(name, repo_dir=None)

Searches the given repo name inside the repo_dir (will use the config value ‘template_repos’ if no repo dir passed), will rise an exception if not found

Parameters:

• name (str) – Name of the repo to search
• repo_dir (str) – Directory where to search the repo

Returns:

path to the repo

Return type:

str

Raises:

RuntimeError – if not found

lago.utils module

class lago.utils.CommandStatus

Bases: lago.utils.CommandStatus

class lago.utils.EggTimer(timeout)

elapsed()

class lago.utils.ExceptionTimer(timeout)

Bases: object

start()

stop()

class lago.utils.Flock(path, readonly=False, blocking=True)

Bases: object

A wrapper class around flock

path

Path to the lock file

Type:str

readonly

If true create a shared lock, otherwise create an exclusive lock.

Type:bool

blocking

lock is already acquired.

Type:bool

acquire()

Acquire the lock

Raises:IOError – if the call to flock fails

release()

exception lago.utils.LagoException

Bases: exceptions.Exception

exception lago.utils.LagoInitException

Bases: lago.utils.LagoException

exception lago.utils.LagoUserException

Bases: lago.utils.LagoException

class lago.utils.LockFile(path, timeout=None, lock_cls=None, **kwargs)

Bases: object

Context manager that creates a file based lock, with optional timeout in the acquire operation.

This context manager should be used only from the main Thread.

Parameters:

• path (str) – path to the dir to lock
• timeout (int) – timeout in seconds to wait while acquiring the lock
• lock_cls (callable) – A callable which returns a Lock object that implements the acquire and release methods. The default is Flock.
• **kwargs (dict) – Any other param to pass to the lock_cls instance.

__enter__()

Start the lock with timeout if needed in the acquire operation

Raises:TimerException – if the timeout is reached before acquiring the lock

class lago.utils.RollbackContext(*args)

Bases: object

A context manager for recording and playing rollback. The first exception will be remembered and re-raised after rollback

Sample usage: > with RollbackContext() as rollback: > step1() > rollback.prependDefer(lambda: undo step1) > def undoStep2(arg): pass > step2() > rollback.prependDefer(undoStep2, arg)

More examples see tests/utilsTests.py @ vdsm code

__exit__(exc_type, exc_value, traceback)

If this function doesn’t return True (or raises a different exception), python re-raises the original exception once this function is finished.

clear()

defer(func, *args, **kwargs)

prependDefer(func, *args, **kwargs)

class lago.utils.TemporaryDirectory(ignore_errors=True)

Bases: object

Context manager that creates a temporary directory and provides its path as a property.

Parameters:ignore_errors (bool) – ignore errors when trying to remove directory Raises:OSError – anything that ‘shutil.rmtree’ might raise

exception lago.utils.TimerException

Bases: exceptions.Exception

Exception to throw when a timeout is reached

class lago.utils.VectorThread(targets)

join_all(raise_exceptions=True)

start_all()

lago.utils._CommandStatus

alias of lago.utils.CommandStatus

lago.utils._add_subparser_to_cp(cp, section, actions, incl_unset)

lago.utils._ret_via_queue(func, queue)

lago.utils._run_command(command, input_data=None, stdin=None, out_pipe=-1, err_pipe=-1, env=None, uuid=None, **kwargs)

Runs a command

Parameters:

• command (list of str) – args of the command to execute, including the command itself as command[0] as [‘ls’, ‘-l’]
• input_data (str) – If passed, will feed that data to the subprocess through stdin
• out_pipe (int or file) – File descriptor as passed to :ref:subprocess.Popen to use as stdout
• stdin (int or file) – File descriptor as passed to :ref:subprocess.Popen to use as stdin
• err_pipe (int or file) – File descriptor as passed to :ref:subprocess.Popen to use as stderr
• of str (env(dict) – str): If set, will use the given dict as env for the subprocess
• uuid (uuid) – If set the command will be logged with the given uuid converted to string, otherwise, a uuid v4 will be generated.
• **kwargs – Any other keyword args passed will be passed to the :ref:subprocess.Popen call

Returns:

result of the interactive execution

Return type:

lago.utils.CommandStatus

lago.utils.add_timestamp_suffix(base_string)

lago.utils.argparse_to_ini(parser, root_section=u'lago', incl_unset=False)

lago.utils.compress(input_file, block_size, fail_on_error=True)

lago.utils.cp(input_file, output_file, fail_on_error=True)

lago.utils.deepcopy(original_obj)

Creates a deep copy of an object with no crossed referenced lists or dicts, useful when loading from yaml as anchors generate those cross-referenced dicts and lists

Parameters:original_obj (object) – Object to deep copy Returns:deep copy of the object Return type:object

lago.utils.filter_spec(spec, paths, wildcard='*', separator='/')

Remove keys from a spec file. For example, with the following path: domains//disks//metadata all the metadata dicts from all domains disks will be removed.

Parameters:

• spec (dict) – spec to remove keys from
• paths (list) – list of paths to the keys that should be removed
• wildcard (str) – wildcard character
• separator (str) – path separator

Returns:

None

Raises:

utils.LagoUserException – If a malformed path was detected

lago.utils.func_vector(target, args_sequence)

lago.utils.get_hash(file_path, checksum='sha1')

Generate a hash for the given file

Parameters:

• file_path (str) – Path to the file to generate the hash for
• checksum (str) – hash to apply, one of the supported by hashlib, for example sha1 or sha512

Returns:

hash for that file

Return type:

str

lago.utils.get_qemu_info(path, backing_chain=False, fail_on_error=True)

Get info on a given qemu disk

Parameters:

• path (str) – Path to the required disk
• backing_chain (boo) – if true, include also info about
• image predecessors. (the) –

Returns:

if backing_chain == True then a list of dicts else a dict

Return type:

object

lago.utils.in_prefix(prefix_class, workdir_class)

lago.utils.invoke_different_funcs_in_parallel(*funcs)

lago.utils.invoke_in_parallel(func, *args_sequences)

lago.utils.ipv4_to_mac(ip)

lago.utils.json_dump(obj, f)

lago.utils.load_virt_stream(virt_fd)

Loads the given conf stream into a dict, trying different formats if needed

Parameters:virt_fd (str) – file like objcect with the virt config to load Returns:Loaded virt config Return type:dict

lago.utils.qemu_rebase(target, backing_file, safe=True, fail_on_error=True)

changes the backing file of ‘source’ to ‘backing_file’ If backing_file is specified as “” (the empty string), then the image is rebased onto no backing file (i.e. it will exist independently of any backing file). (Taken from qemu-img man page)

Parameters:

• target (str) – Path to the source disk
• backing_file (str) – path to the base disk
• safe (bool) – if false, allow unsafe rebase (check qemu-img docs for more info)

lago.utils.read_nonblocking(file_descriptor)

lago.utils.rotate_dir(base_dir)

lago.utils.run_command(command, input_data=None, out_pipe=-1, err_pipe=-1, env=None, **kwargs)

Runs a command non-interactively

Parameters:

• command (list of str) – args of the command to execute, including the command itself as command[0] as [‘ls’, ‘-l’]
• input_data (str) – If passed, will feed that data to the subprocess through stdin
• out_pipe (int or file) – File descriptor as passed to :ref:subprocess.Popen to use as stdout
• err_pipe (int or file) – File descriptor as passed to :ref:subprocess.Popen to use as stderr
• of str (env(dict) – str): If set, will use the given dict as env for the subprocess
• **kwargs – Any other keyword args passed will be passed to the :ref:subprocess.Popen call

Returns:

result of the interactive execution

Return type:

lago.utils.CommandStatus

lago.utils.run_command_with_validation(cmd, fail_on_error=True, msg='An error has occurred')

lago.utils.run_interactive_command(command, env=None, **kwargs)

Runs a command interactively, reusing the current stdin, stdout and stderr

Parameters:

• command (list of str) – args of the command to execute, including the command itself as command[0] as [‘ls’, ‘-l’]
• of str (env(dict) – str): If set, will use the given dict as env for the subprocess
• **kwargs – Any other keyword args passed will be passed to the :ref:subprocess.Popen call

Returns:

result of the interactive execution

Return type:

lago.utils.CommandStatus

lago.utils.service_is_enabled(name)

lago.utils.sparse(input_file, input_format, fail_on_error=True)

lago.utils.ver_cmp(ver1, ver2)

Compare lago versions

Parameters:

• ver1 (str) – version string
• ver2 (str) – version string

Returns:

Return negative if ver1<ver2, zero if ver1==ver2, positive if ver1>ver2.

lago.utils.with_logging(func)

lago.validation module

lago.validation.check_import(module_name)

Search if a module exists, and it is possible to try importing it

Parameters:module_name (str) – module to import Returns:True if the package is found Return type:bool

lago.virt module

exception lago.virt.LagoUnknownVMTypeError(vm_type_name, vm_types)

Bases: lago.utils.LagoUserException

class lago.virt.VirtEnv(prefix, vm_specs, net_specs)

Bases: object

Env properties: * prefix * vms * net

_create_net(net_spec, compat)

_create_vm(vm_spec)

_get_stop_shutdown_common_args(vm_names)

Get the common arguments for stop and shutdown commands :param vm_names: The names of the requested vms :type vm_names: list of str

Returns

list of plugins.vm.VMProviderPlugin:

vms objects that should be stopped

list of virt.Network: net objects that should be stopped str: log message

Raises:utils.LagoUserException – If a vm name doesn’t exist

_get_unused_nets(vms_to_stop)

Return a list of nets that used only by the vms in vms_to_stop :param vms_to_stop: The names of the requested vms :type vms_to_stop: list of str

Returns

list of virt.Network: net objects that used only by

vms in vms_to_stop

Raises:utils.LagoUserException – If a vm name doesn’t exist

bootstrap()

create_snapshots(**kwargs)

export_vms(vms_names, standalone, dst_dir, compress, init_file_name, out_format, collect_only=False, with_threads=True)

classmethod from_prefix(prefix)

generate_init(dst, out_format, vms_to_include, filters=None)

Generate an init file which represents this env and can be used with the images created by self.export_vms :param dst: path and name of the new init file :type dst: str :param out_format: formatter for the output (the default is yaml) :type out_format: plugins.output.OutFormatPlugin :param filters: list of paths to keys that should be removed from

the init file

Parameters:(list of (vms_to_include) – class:lago.plugins.vm.VMPlugin): list of vms to include in the init file Returns:None

get_compat()

Get compatibility level for this environment - which is the Lago version used to create this environment

get_env_spec(filters=None)

Get the spec of the current env. The spec will hold the info about all the domains and networks associated with this env. :param filters: list of paths to keys that should be removed from

the init file

Returns:the spec of the current env Return type:dict

get_net(name=None)

get_nets()

get_snapshots(domains=None)

Get the list of snapshots for each domain :param domanins: list of the domains to get the snapshots :type domanins: list of str :param for, all will be returned if none or empty list passed:

Returns:with the domain names and the list of snapshots for each Return type:dict of str -> list(str)

get_vm(name)

get_vms(vm_names=None)

Returns the vm objects associated with vm_names if vm_names is None, return all the vms in the prefix :param vm_names: The names of the requested vms :type vm_names: list of str

Returns

dict: Which contains the requested vm objects indexed by name

Raises:utils.LagoUserException – If a vm name doesn’t exist

prefixed_name(unprefixed_name, max_length=0)

Returns a uuid pefixed identifier :param unprefixed_name: Name to add a prefix to :type unprefixed_name: str :param max_length: maximum length of the resultant prefixed name,

will adapt the given name and the length of the uuid ot fit it

Returns:prefixed identifier for the given unprefixed name Return type:str

revert_snapshots(**kwargs)

save(**kwargs)

shutdown(vm_names, reboot=False)

start(vm_names=None)

stop(vm_names=None)

virt_path(*args)

lago.virt._gen_ssh_command_id()

lago.virt._guestfs_copy_path(g, guest_path, host_path)

lago.virt._path_to_xml(basename)

lago.virt.log_task(task, level='info', propagate_fail=True, uuid=None)

Parameterized decorator to wrap a function in a log task

Example

>>> @log_task('mytask')
... def do_something():
...     pass

lago.vm module

class lago.vm.DefaultVM(env, spec)

Bases: lago.plugins.vm.VMPlugin

_abc_cache = <_weakrefset.WeakSet object>

_abc_negative_cache = <_weakrefset.WeakSet object>

_abc_negative_cache_version = 43

_abc_registry = <_weakrefset.WeakSet object>

class lago.vm.SSHVMProvider(vm)

Bases: lago.plugins.vm.VMProviderPlugin

bootstrap(*args, **kwargs)

Does any actions needed to get the domain ready to be used, ran on prefix init. :returns: None

create_snapshot(name, *args, **kwargs)

Take any actions needed to create a snapshot :param name: Name for the snapshot, will be used as key to retrieve

it later

Returns:None

defined(*args, **kwargs)

revert_snapshot(name, *args, **kwargs)

Take any actions needed to revert/restore a snapshot :param name: Name for the snapshot, same that was set on creation :type name: str

Returns:None

running(*args, **kwargs)

Returns: (bool): True if the VM is running

start(*args, **kwargs)

Start a domain :returns: None

state(*args, **kwargs)

Return the current state of the domain :returns: Small description of the current domain state :rtype: str

stop(*args, **kwargs)

Stop a domain :returns: None

lago.workdir module

exception lago.workdir.LagoPrefixAlreadyExistsError(prefix_name, workdir_path)

Bases: lago.utils.LagoException

exception lago.workdir.MalformedWorkdir

Bases: lago.workdir.WorkdirError

exception lago.workdir.PrefixAlreadyExists

Bases: lago.workdir.WorkdirError

exception lago.workdir.PrefixNotFound

Bases: lago.workdir.WorkdirError

class lago.workdir.Workdir(path, prefix_class=<class 'lago.prefix.Prefix'>)

Bases: object

This class reperesents a base workdir, where you can store multiple prefixes

Properties:

path(str): Path to the workdir perfixes(dict of str->self.prefix_class): dict with the prefixes in the workdir, by name current(str): Name of the current prefix prefix_class(type): Class to use when creating prefixes

_set_current(new_current)

Change the current default prefix, for internal usage

Parameters:new_current (str) – Name of the new current prefix, it must already exist Returns:None Raises:PrefixNotFound – if the given prefix name does not exist in the workdir

_update_current()

Makes sure that a current is set

add_prefix(*args, **kwargs)

Adds a new prefix to the workdir.

Parameters:

• name (str) – Name of the new prefix to add
• *args – args to pass along to the prefix constructor
• *kwargs – kwargs to pass along to the prefix constructor

Returns:

The newly created prefix

Raises:

• LagoPrefixAlreadyExistsError – if prefix name already exists in the
• workdir

cleanup()

Attempt to set a new current symlink if it is broken. If no other prefixes exist and the workdir is empty, try to delete the entire workdir.

Raises:MalformedWorkdir – if no prefixes were found, but the workdir is not empty.

destroy(*args, **kwargs)

Destroy all the given prefixes and remove any left files if no more prefixes are left

Parameters:

• prefix_names (list of str) – list of prefix names to destroy, if None
• passed (default) –

get_prefix(*args, **kwargs)

Retrieve a prefix, resolving the current one if needed

Parameters:name (str) – name of the prefix to retrieve, or current to get the current one Returns:instance of the prefix with the given name Return type:self.prefix_class

initialize(prefix_name='default', *args, **kwargs)

Initializes a workdir by adding a new prefix to the workdir.

Parameters:

• prefix_name (str) – Name of the new prefix to add
• *args – args to pass along to the prefix constructor
• *kwargs – kwargs to pass along to the prefix constructor

Returns:

The newly created prefix

Raises:

PrefixAlreadyExists – if the prefix name already exists in the workdir

static is_possible_workdir(path)

A quick method to suggest if the path is a possible workdir. This does not guarantee that the workdir is not malformed, only that by simple heuristics it might be one. For a full check use is_workdir().

Parameters:path (str) – Path Returns:True if path might be a work dir. Return type:bool

classmethod is_workdir(path)

Check if the given path is a workdir

Parameters:path (str) – Path to check Returns:True if the given path is a workdir Return type:bool

join(*args)

Gets a joined path prefixed with the workdir path

Parameters:*args (str) – path sections to join Returns:Joined path prefixed with the workdir path Return type:str

load()

Loads the prefixes that are available is the workdir

Returns:None Raises:MalformedWorkdir – if the wordir is malformed

classmethod resolve_workdir_path(start_path='.')

Look for an existing workdir in the given path, in a path/.lago dir, or in a .lago dir under any of it’s parent directories

Parameters:start_path (str) – path to start the search from, if None passed, it will use the current dir Returns:path to the found prefix Return type:str Raises:LagoUserException – if no prefix was found

set_current(*args, **kwargs)

Change the current default prefix

Parameters:new_current (str) – Name of the new current prefix, it must already exist Returns:None Raises:PrefixNotFound – if the given prefix name does not exist in the workdir

exception lago.workdir.WorkdirError

Bases: exceptions.RuntimeError

Base exception for workdir errors, catch this one to catch any workdir error

lago.workdir.workdir_loaded(func)

Decorator to make sure that the workdir is loaded when calling the decorated function