Charm architecture

The SAML Integrator charm fetches SAML metadata details based on the provided configuration and propagates them through a Juju integration.

The SAML Integrator can be deployed in Kubernetes and machine models. As a workloadless charm, the SAML Integrator doesn’t have any OCI images.

The metadata can be provided directly, through the configuration option metadata, or it can be provided through the configuration option metadata_url. In the latter case, the SAML integrator charm will get the XML SAML metadata document from the provided URL. From the metadata information, the entity_id, x509certs and endpoints information will be extracted and passed in the SAML integration.

The charm provides a library to facilitate the development of charms that use the SAML integration.

Juju events

According to the Juju SDK: “an event is a data structure that encapsulates part of the execution context of a charm”.

For this charm, the following events are observed:

1. config-changed: usually fired in response to a configuration change using the GUI or CLI. Action: validate the configuration and fetch the SAML details from the metadata. If there are relations, update the SAML details in the relation databag.
2. saml-relation-created: Custom event for when a new SAML relations is created. Action: write the SAML details in the relation databag.
3. update-status: Fired periodically by Juju. Action: write the SAML details in the relation databag if data has changed.

Charm code overview

The src/charm.py is the default entry point for a charm and has the SamlIntegratorOperatorCharm Python class which inherits from CharmBase.

CharmBase is the base class from which all Charms are formed, defined by Ops (Python framework for developing charms).

See more information in Ops documentation.

The __init__ method guarantees that the charm observes all events relevant to its operation and handles them.