Transports

Abstract transport and state machine for hosts state.

class cumin.transports.Command(command, timeout=None, ok_codes=None)

Bases: object

Class to represent a command.

Command constructor.

Parameters

• command (str) -- the command to execute.

• timeout (int, optional) -- the command's timeout in seconds.

• ok_codes (list, optional) -- a list of exit codes to be considered successful for the command. The exit code zero is considered successful by default, if this option is set it override it. If set to an empty list [], it means that any code is considered successful.

__repr__()

Return the representation of the Command.

The representation allow to instantiate a new Command instance with the same properties.

Returns

the representation of the object.

Return type

str

__str__()

Return the string representation of the command.

Returns

the string representation of the object.

Return type

str

__eq__(other)

Equality operation. Allow to directly compare a Command object to another or a string.

Parameters

according to Python's Data model object.__eq__().

Returns

True if the other object is equal to this one, False otherwise.

Return type

bool

Raises

exceptions.ValueError -- if the comparing object is not an instance of Command or a str.

__ne__(other)

Inequality operation. Allow to directly compare a Command object to another or a string.

Parameters

according to Python's Data model object.__ne__().

Returns

True if the other object is different to this one, False otherwise.

Return type

bool

Raises

exceptions.ValueError -- if the comparing object is not an instance of Command or a str.

property timeout

Timeout of the Command.

Getter

Returns the current timeout or None if not set.

Setter

float, int, None: the timeout in seconds for the execution of the command on each host. Both float and int are accepted and converted internally to float. If None the timeout is reset to its default value.

Raises

cumin.transports.WorkerError -- if trying to set it to an invalid value.

property ok_codes

List of exit codes to be considered successful for the execution of the Command.

Getter

Returns the current ok_codes or a list with the element 0 if not set.

Setter

list[int], None: list of exit codes to be considered successful for the execution of the command on each host. Must be a list of int in the range 0-255 included, or None to unset it. The exit code 0 is considered successful by default, but it can be overriden setting this property. Set it to an empty list to consider any exit code successful.

Raises

cumin.transports.WorkerError -- if trying to set it to an invalid value.

class cumin.transports.State(init=None)

Bases: object

State machine for the state of a host.

current

int: the current state.

is_pending

bool: True if the current state is pending, False otherwise.

is_scheduled

bool: True if the current state is scheduled, False otherwise.

is_running

bool: True if the current state is running, False otherwise.

is_success

bool: True if the current state is success, False otherwise.

is_failed

bool: True if the current state is failed, False otherwise.

is_timeout

bool: True if the current state is timeout, False otherwise.

State constructor. The initial state is set to pending it not provided.

Parameters

init (int, optional) -- the initial state from where to start. The pending state will be used if not set.

Raises

cumin.transports.InvalidStateError -- if init is an invalid state.

valid_states = range(0, 6)

valid states integer indexes.

Type

list

pending = 0

Valid state property, one for each cumin.transports.State.valid_states.

scheduled = 1

Valid state property, one for each cumin.transports.State.valid_states.

running = 2

Valid state property, one for each cumin.transports.State.valid_states.

success = 3

Valid state property, one for each cumin.transports.State.valid_states.

failed = 4

Valid state property, one for each cumin.transports.State.valid_states.

timeout = 5

Valid state property, one for each cumin.transports.State.valid_states.

states_representation = ('pending', 'scheduled', 'running', 'success', 'failed', 'timeout')

Tuple with the string representations of the valid states.

Type

tuple()

allowed_state_transitions = {0: (1,), 1: (2,), 2: (2, 3, 4, 5), 3: (0,), 4: (), 5: ()}

Dictionary with {valid state: tuple of valid states} mapping of the allowed transitions between all the possile states.

This is the diagram of the allowed transitions:

Type

dict

__getattr__(name)

Attribute accessor.

Accessible properties

• current (int): retuns the current state.

• is_{valid_state_name} (bool): for each valid state name, returns True if the current state matches the state in the variable name. False otherwise.

Parameters

according to Python's Data model object.__getattr__().

Raises

exceptions.AttributeError -- if the attribute name is not available.

__repr__()

Return the representation of the State.

The representation allow to instantiate a new State instance with the same properties.

Returns

the representation of the object.

Return type

str

__str__()

Return the string representation of the state.

Returns

the string representation of the object.

Return type

str

update(new)

Transition the state from the current state to the new one, if the transition is allowed.

Parameters

new (int) -- the new state to set. Only specific state transitions are allowed.

Raises

cumin.transports.StateTransitionError -- if the transition is not allowed, see allowed_state_transitions.

_cmp(other)

Comparison operation. Allow to directly compare a state object to another or to an integer.

Parameters

other (mixed) -- the object to compare the current instance to.

Raises

ValueError -- if the comparing object is not an instance of State or an integer.

exception cumin.transports.WorkerError

Bases: cumin.CuminError

Custom exception class for worker errors.

exception cumin.transports.StateTransitionError

Bases: cumin.CuminError

Exception raised when an invalid transition for a node's State was attempted.

exception cumin.transports.InvalidStateError

Bases: cumin.CuminError

Exception raised when an invalid transition for a node's State was attempted.

class cumin.transports.Target(hosts, batch_size=None, batch_size_ratio=None, batch_sleep=None)

Bases: object

Targets management class.

Constructor, inizialize the Target with the list of hosts and additional parameters.

Parameters

• hosts (ClusterShell.NodeSet.NodeSet, list) -- hosts that will be targeted, both ClusterShell.NodeSet.NodeSet and list are accepted and converted automatically to ClusterShell.NodeSet.NodeSet internally.

• batch_size (int, optional) -- set the batch size so that no more that this number of hosts are targeted at any given time. It must be a positive integer. If greater than the number of hosts it will be auto-resized to the number of hosts.

• batch_size_ratio (float, optional) -- set the batch size with a ratio so that no more that this fraction of hosts are targeted at any given time. It must be a float between 0 and 1 and will raise exception if after rounding it there are 0 hosts selected.

• batch_sleep (float, optional) -- sleep time in seconds between the end of execution of one host in the batch and the start in the next host. It must be a positive float.

Raises

cumin.transports.WorkerError -- if the hosts parameter is empty or invalid, if both the batch_size and batch_size_ratio parameters are set or if the batch_size_ratio selects no hosts.

property first_batch

First batch of the hosts to target.

Getter

Returns a ClusterShell.NodeSet.NodeSet of the first batch of hosts, according to the batch_size.

_compute_batch_size(batch_size, hosts)

Compute the batch_size based on the hosts size and return the value to be used.

Parameters

• batch_size (int, None) -- a positive integer to indicate the batch_size to apply when executing the worker or None to get its default value of all the hosts. If greater than the number of hosts, the number of hosts will be used as value instead.

• hosts (ClusterShell.NodeSet.NodeSet) -- the list of hosts to use to calculate the batch size.

Returns

the effective batch_size to use.

Return type

int

static _compute_batch_sleep(batch_sleep)

Validate batch_sleep and return its value or a default value.

Parameters

batch_sleep (float, None) -- a positive float indicating the sleep in seconds to apply between one batched host and the next, or None to get its default value.

Returns

the effective batch_sleep to use.

Return type

float

class cumin.transports.BaseWorker(config, target)

Bases: object

abstract Worker interface to be extended by concrete workers.

Worker constructor. Setup environment variables and initialize properties.

Parameters

• config (dict) -- a dictionary with the parsed configuration file.

• target (Target) -- a Target instance.

abstract execute()

Execute the task as configured.

Returns

0 on success, a positive integer on failure.

Return type

int

Raises

cumin.transports.WorkerError -- if misconfigured.

abstract get_results()

Iterate over the results (generator).

Yields

tuple -- with (hosts, result) for each host(s) of the current execution.

property commands

Commands for the current execution.

Getter

Returns the current command list or an empty list if not set.

Setter

list[Command], list[str]: a list of Command objects or str to be executed in the hosts. The elements are converted to Command automatically.

Raises

cumin.transports.WorkerError -- if trying to set it with invalid data.

abstract property handler

Get and set the handler for the current execution.

Getter

Returns the current handler or None if not set.

Setter

str, EventHandler, None: an event handler to be notified of the progress during execution. Its interface depends on the actual transport chosen. Accepted values are: * None => don't use an event handler (default) * str => a string label to choose one of the available default EventHandler classes in that transport, * an event handler class object (not instance)

property timeout

Global timeout for the current execution.

Getter

int: returns the current timeout or 0 (no timeout) if not set.

Setter

int, None: timeout for the current execution in seconds. Must be a positive integer or None to reset it.

Raises

cumin.transports.WorkerError -- if trying to set it to an invalid value.

property success_threshold

Success threshold for the current execution.

Getter

float: returns the current success_threshold or 1.0 (100%) if not set.

Setter

float, None: The success ratio threshold that must be reached to consider the run successful. A float between 0 and 1 or None to reset it. The specific meaning might change based on the chosen transport.

Raises

cumin.transports.WorkerError -- if trying to set it to an invalid value.

cumin.transports.validate_list(property_name, value, allow_empty=False)

Validate a list.

Parameters

• property_name (str) -- the name of the property to validate.

• value (list) -- the value to validate.

• allow_empty (bool, optional) -- whether to consider an empty list valid.

Raises

cumin.transports.WorkerError -- if trying to set it to an invalid value.

cumin.transports.validate_positive_integer(property_name, value)

Validate a positive integer or None.

Parameters

• property_name (str) -- the name of the property to validate.

• value (int, None) -- the value to validate.

Raises

cumin.transports.WorkerError -- if trying to set it to an invalid value.

cumin.transports.validate_positive_float(property_name, value)

Validate a positive float or None.

Parameters

• property_name (str) -- the name of the property to validate.

• value (float, None) -- the value to validate.

Raises

cumin.transports.WorkerError -- if trying to set it to an invalid value.

cumin.transports.raise_error(property_name, message, value)

Raise a WorkerError exception.

Parameters

• property_name (str) -- the name of the property that raised the exception.

• message (str) -- the message to use for the exception.

• value (mixed) -- the value that raised the exception.

class cumin.transports.ProgressBars

Bases: object

Progress bars for the status of successful / failed hosts.

The ProgressBars needs to be notified of the total number of hosts when the operation starts, and then notified of successes and failures.

Create the progress bars.

Note

the progress bars themselves are not initalized at object creation. init() needs to be called before using the progress bars.

init(num_hosts)

Initialize the progress bars.

Parameters

num_hosts (int) -- the total number of hosts

close()

Closes the progress bars.

update_success(num_hosts=1)

Updates the number of successful hosts.

Parameters

num_hosts (int) -- increment to the number of hosts that have completed successfully

update_failed(num_hosts=1)

Updates the number of failed hosts.

Parameters

num_hosts (int) -- increment to the number of hosts that have completed in error

class cumin.transports.NoProgress

Bases: object

Used as a null object to disable the display of progress bars.

init(num_hosts)

Does nothing.

close()

Does nothing.

update_success(num_hosts=1)

Does nothing.

update_failed(num_hosts=1)

Does nothing.

Available transports

• ClusterShell