Roles Core

chaos.lib.roles.role

Abstract base class definition for Ch-aOS execution roles.

Role

Bases: ABC

Abstract base class for roles in the Ch-aOS framework.

Notes

Each role must implement the "get_context", "delta" and "plan" methods to define its behavior and interactions for system management and orchestration.

get_context: This method should return the necessary data and information present in the system for the specific context of the role.

delta: This method should calculate what it needs to do to achieve its goals based on the current context and the desired state.

plan: This method should only stack the actions needed in pyinfra operations to achieve the desired state.

__init__(name, needs_secrets=False, necessary_chobolo_keys=[], necessary_secret_dict_keys=[])

Initializes a Role.

Parameters:

Name	Type	Description	Default
name	str	The name of the role.	required
needs_secrets	bool	Indicates if the role requires secrets to operate. Defaults to False.	False
necessary_chobolo_keys	list[str]	The list of configuration keys required from the chobolo state. Defaults to [].	[]
necessary_secret_dict_keys	list[str]	The list of secret keys required from the secrets store. Defaults to [].	[]

delta(context={})

Optional method to implement for roles that require calculating a delta to achieve their goals.

Parameters:

Name	Type	Description	Default
context	dict[str, Any]	The context for the role, as returned by the get_context method. Defaults to {}.	{}

Returns:

Name	Type	Description
Delta	Delta	A Delta object containing the actions needed to achieve the desired state.

Notes

This method should be implemented by subclasses to calculate what it needs to do to achieve its goals based on the current context and the desired state.

get_context(state, host, chobolo={}, secrets={})

Optional method to implement for roles that require context data from the system.

Parameters:

Name	Type	Description	Default
state	State	Pyinfra state object.	required
host	Host	Pyinfra host object.	required
chobolo	dict	The desired state of the system as represented in the Chobolo. It contains only the keys specified in the "necessary_chobolo_keys" attribute of the role merged with the secret keys specified in the "necessary_secret_dict_keys" attribute of the role. Defaults to {}.	{}
secrets	dict[str, Any]	The secrets required for the role, if any. Defaults to {}.	{}

Returns:

Type	Description
dict[str, Any]	dict[str, Any]: A dictionary containing the context for the role.

Notes

This method should be implemented by subclasses to return the necessary data and information present in the system for the specific context of the role.

plan(state, host, delta=Delta()) abstractmethod

Plan the actions needed to achieve the desired state.

Parameters:

Name	Type	Description	Default
state	State	Pyinfra state object.	required
host	Host	Pyinfra host object.	required
delta	Delta	The delta for the role, as returned by the delta method. Defaults to Delta().	Delta()

Returns:

Name	Type	Description
ResultPayload	ResultPayload	A ResultPayload object containing the result of the operation addition process including relevant data.

Notes

This method should be implemented by subclasses to stack the actions needed in pyinfra operations to achieve the desired state.