refactor: relation naming

[SimonRichardson]

The relation names weren't ideal in the grand scheme of usage in the controller snap. Instead, if we naming the correctly it should allow us to add better versioning in the future.

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Setup Tempo

Build the charm with charmcraft pack

To make this proper, we need a COS-lite or something similar. I used COS-lite on microk8s and then deployed tempo in the same model.

Once there is a COS-lite with tempo we need to offer the tempo:tracing relation.

$ juju offer tempo:tracing

Controller charm setup

To make this "simple" we can only deploy a local controller charm using IAAS controllers. So we need to bootstrap a IAAS controller (again for simplicity I'm using LXD).

$ juju bootstrap lxd test --bootstrap-base=ubuntu@24.04 --controller-charm-path=./juju-controller_ubuntu@24.04-amd64.charm
$ juju switch controller
$ juju consume cos:admin/lite.tempo
$ juju integrate controller:charm-tracing tempo:tracing

Verify the endpoints are consumed

$ juju ssh -m test:controller controller 0
$ juju_db_repl
repl (controller)> SELECT * FROM charm_tracing_config
key             value
http-endpoint   http://tempo.m.svc.cluster.local:4318
grpc-endpoint   tempo.m.svc.cluster.local:4317

Verify that the information is set as vars:

$ juju debug-hook -m controller controller/0

You might have to trigger a hook invocation with something like juju config -m controller controller identity-provider-url="foo".

root@juju-2bd818-0:/var/lib/juju/agents/unit-controller-0/charm# printenv | grep -E "JUJU_CHARM_TRACE_CONFIG_(H|G)"
JUJU_CHARM_TRACE_CONFIG_HTTP=http://tempo.lite.svc.cluster.local:4318
JUJU_CHARM_TRACE_CONFIG_GRPC=tempo.lite.svc.cluster.local:4317

🎉