Expose Minio Console and API via Ingress

[ca-scribner]

Adds an ingress relation to that sends the console and api

fixes #40

[ca-scribner]

There's a few linting errors (see tox -e lint) to fix up

[ca-scribner]

This'll define the endpoint that we claim on the ingress, as written we've claimed the root (or really, http://INGRESS_URL/). It probably makes the most sense that this be configurable via a config option. The config option could accept anything that would be valid in a URL (a good default value could be /minio).

[ca-scribner]

Can this prefix and the above one be the same? I don't know this for sure, but my expectation is that they will conflict. I think these might need to be something like "prefix": "/SOME_VALUE_FROM_CONFIG/console" and "/SOME_VALUE_FROM_CONFIG/api" (or whatever good name you suggest)

[jardon]

I am not sure either. I didn't consider it because the ports are different, but it doesnt serve it on the same port I would assume

[ca-scribner]

I think the only external facing thing is the prefix, and then the port is used when routing to the kubernetes service (eg: INGRESS/PREFIX routes to SERVICE:PORT inside kubernetes)

[ca-scribner]

This test can work as a general "can I successfully invoke pod_spec" test, but I think we are missing something to actually check whether this charm has published what we expect to the relation. For example, like here

[phvalguima]

@jardon it is missing the following entries:

        for event in [
            self.on.config_changed,
            self.on.install,
            self.on.upgrade_charm,
            self.on["object-storage"].relation_changed,
            self.on["object-storage"].relation_joined,
            self.on["console-ingress"].relation_changed, ## <<<---------- add this line
            self.on["console-ingress"].relation_joined,     ## <<<---------- add this line
        ]:
            self.framework.observe(event, self.main)

Otherwise it will not work if the relation is added after minio has been deployed