sborl - Schema-based Operator Relation Libraries

This library provides a base for creating relation endpoint libraries for use with charmed operators and Juju. It tries to make creating Pythonic implementations of a relation interface protocol straightforward and approachable, while encouraging good patterns such as using schema-based interface protocol validation, providing helpers for testing charms using your library, and surfacing problems with relations in a clean way.

Example

An example endpoint class and usage might look like:

class RandomURLRequirer(sborl.relation.EndpointWrapper):
    INTERFACE = "random-url"
    ROLE = "requires"
    SCHEMA = Path(__file__) / "schema.yaml"
    LIMIT = 1

    @property
    def url(self):
        if not self.is_ready():
            return None
        relation = self.relations[0]
        return self.unwrap(relation)[relation.app]["url"]


class MyCharm(ops.charm.CharmBase):
    def __init__(self, *args):
        super().__init__(*args)
        self.random_url = RandomURLRequirer(charm=self, endpoint="random-url-provider")
        self.framework.observe(self.random_url.on.ready, self._log_url)

    def _log_url(self, event):
        log.info(f"Got random URL: {self.random_url.url}")