ContextProvider

class aws_cdk.ContextProvider(*args: Any, **kwargs)

Bases: object

Base class for the model side of context providers.

Instances of this class communicate with context provider plugins in the ‘cdk toolkit’ via context variables (input), outputting specialized queries for more context variables (output).

ContextProvider needs access to a Construct to hook into the context mechanism.

Static Methods

classmethod get_key(scope, *, provider, include_environment=None, props=None)
Parameters:

  • scope (Construct) –

  • provider (str) – The context provider to query.

  • include_environment (Optional[bool]) – Whether to include the stack’s account and region automatically. Default: true

  • props (Optional[Mapping[str, Any]]) – Provider-specific properties.

Return type:

GetContextKeyResult

Returns:

the context key or undefined if a key cannot be rendered (due to tokens used in any of the props)

classmethod get_value(scope, *, dummy_value, ignore_error_on_missing_context=None, must_exist=None, provider, include_environment=None, props=None)
Parameters:

  • scope (Construct) –

  • dummy_value (Any) – The value to return if the lookup has not yet been performed. Upon first synthesis, the lookups has not yet been performed. The getValue() operation returns this value instead, so that synthesis can proceed. After synthesis completes the first time, the actual lookup will be performed and synthesis will run again with the real value. Dummy values should preferably have valid shapes so that downstream consumers of lookup values don’t throw validation exceptions if they encounter a dummy value (or all possible downstream consumers need to effectively check for the well-known shape of the dummy value); throwing an exception would error out the synthesis operation and prevent the lookup and the second, real, synthesis from happening. Connection to mustExist dummyValue is also used as the official value to return if the lookup has failed and mustExist == false.

  • ignore_error_on_missing_context (Optional[bool]) – (deprecated) Ignore a lookup failure and return the dummyValue instead. mustExist is the recommended alias for this deprecated property (note that its value is reversed). Default: false

  • must_exist (Optional[bool]) – Whether the resource must exist. If this is set (the default), the query fails if the value or resource we tried to look up doesn’t exist. If this is false and the value we tried to look up could not be found, the failure is suppressed and dummyValue is officially returned instead. When this happens, dummyValue is encoded into cached context and it will never be refreshed anymore until the user runs cdk context --reset <key>. Note that it is not possible for the CDK app code to make a distinction between “the lookup has not been performed yet” and “the lookup didn’t find anything and we returned a default value instead”. Context providers This feature must explicitly be supported by context providers. It is currently supported by: - KMS key provider - SSM parameter provider Note to implementors The dummy value should not be returned for all SDK lookup failures. For example, “no network” or “no credentials” or “malformed query” should not lead to the dummy value being returned. Only the case of “no such resource” should. Default: true

  • provider (str) – The context provider to query.

  • include_environment (Optional[bool]) – Whether to include the stack’s account and region automatically. Default: true

  • props (Optional[Mapping[str, Any]]) – Provider-specific properties.

Return type:

GetContextValueResult