runway.variables module

Runway variables.

runway.variables.resolve_variables(variables, context, provider)

Given a list of variables, resolve all of them.

Parameters

• variables (List[Variable]) – List of variables.

• context (runway.cfngin.context.Context) – CFNgin context.

• provider (runway.cfngin.providers.base.BaseProvider) – Subclass of the base provider.

class runway.variables.Variable(name, value, variable_type='cfngin')

Bases: object

Represents a variable provided to a Runway directive.

Initialize class.

Parameters

• name – Name of the variable (directive/key).

• value – The variable itself.

• variable_type – Type of variable (cfngin|runway).

property dependencies

Stack names that this variable depends on.

Returns

Stack names that this variable depends on.

Return type

Set[str]

property resolved

Boolean for whether the Variable has been resolved.

Variables only need to be resolved if they contain lookups.

property value

Return the current value of the Variable.

resolve(context, provider=None, variables=None, **kwargs)

Resolve the variable value.

Parameters

• context – The current context object.

• provider – Subclass of the base provider.

• variables – Object containing variables passed to Runway.

get(key, default=None)

Implement evaluation of self.get.

Parameters

• key – Attribute name to return the value for.

• default – Value to return if attribute is not found.

class runway.variables.VariableValue

Bases: object

Syntax tree base class to parse variable values.

property dependencies

Stack names that this variable depends on.

property resolved

Use to check if the variable value has been resolved.

Should be implimented in subclasses.

property simplified

Return a simplified version of the value.

This can be used to concatenate two literals into one literal or flatten nested concatenations.

Should be implimented in subclasses where applicable.

property value

Value of the variable. Can be resolved or unresolved.

Should be implimented in subclasses.

resolve(context, provider=None, variables=None, **kwargs)

Resolve the variable value.

Parameters

• context – The current context object.

• provider – Subclass of the base provider.

• variables – Object containing variables passed to Runway.

classmethod parse(input_object, variable_type='cfngin')

Parse complex variable structures using type appropriate subclasses.

Parameters

• input_object – The objected defined as the value of a variable.

• variable_type – Type of variable (cfngin|runway).

class runway.variables.VariableValueLiteral(value)

Bases: runway.variables.VariableValue

The literal value of a variable as provided.

Initialize class.

property resolved

Use to check if the variable value has been resolved.

The ValueLiteral will always appear as resolved because it does not “resolve” since it is the literal definition of the value.

property value

Value of the variable.

class runway.variables.VariableValueList

Bases: runway.variables.VariableValue, list

A list variable value.

property dependencies

Stack names that this variable depends on.

property resolved

Use to check if the variable value has been resolved.

property simplified

Return a simplified version of the value.

This can be used to concatenate two literals into one literal or flatten nested concatenations.

property value

Value of the variable. Can be resolved or unresolved.

resolve(context, provider=None, variables=None, **kwargs)

Resolve the variable value.

Parameters

• context – The current context object.

• provider – Subclass of the base provider.

• variables – Object containing variables passed to Runway.

classmethod parse(input_object, variable_type='cfngin')

Parse list variable structure.

Parameters

• input_object – The objected defined as the value of a variable.

• variable_type – Type of variable (cfngin|runway).

class runway.variables.VariableValueDict

Bases: runway.variables.VariableValue, dict

A dict variable value.

property dependencies

Stack names that this variable depends on.

property resolved

Use to check if the variable value has been resolved.

property simplified

Return a simplified version of the value.

This can be used to concatenate two literals into one literal or flatten nested concatenations.

property value

Value of the variable. Can be resolved or unresolved.

resolve(context, provider=None, variables=None, **kwargs)

Resolve the variable value.

Parameters

• context – The current context object.

• provider – Subclass of the base provider.

• variables – Object containing variables passed to Runway.

classmethod parse(input_object, variable_type='cfngin')

Parse list variable structure.

Parameters

• input_object – The objected defined as the value of a variable.

• variable_type – Type of variable (cfngin|runway).

class runway.variables.VariableValueConcatenation

Bases: runway.variables.VariableValue, list

A concatinated variable value.

property dependencies

Stack names that this variable depends on.

property resolved

Use to check if the variable value has been resolved.

property simplified

Return a simplified version of the value.

This can be used to concatenate two literals into one literal or flatten nested concatenations.

property value

Value of the variable. Can be resolved or unresolved.

resolve(context, provider=None, variables=None, **kwargs)

Resolve the variable value.

Parameters

• context – The current context object.

• provider – Subclass of the base provider.

• variables – Object containing variables passed to Runway.

class runway.variables.VariableValueLookup(lookup_name, lookup_data, handler=None, variable_type='cfngin')

Bases: runway.variables.VariableValue

A lookup variable value.

Initialize class.

Parameters

• lookup_name – Name of the invoked lookup

• lookup_data – Data portion of the lookup

• handler – Lookup handler that will be use to resolve the value.

• variable_type – Type of variable (cfngin|runway).

property dependencies

Stack names that this variable depends on.

property resolved

Use to check if the variable value has been resolved.

property simplified

Return a simplified version of the value.

This can be used to concatenate two literals into one literal or flatten nested concatenations.

property value

Value of the variable. Can be resolved or unresolved.

resolve(context, provider=None, variables=None, **kwargs)

Resolve the variable value.

Parameters

• context – The current context object.

• provider – Subclass of the base provider.

• variables – Object containing variables passed to Runway.

Raises

FailedLookup – A lookup failed for any reason.