Fix handling of tls config

[sed-i]

Issue

TLS config is written and workload restarted, before the cert is written to disk.

Solution

• [x] Use rock from https://github.com/canonical/prometheus-rock/pull/30
  • [x] Use the update-ca-certificates machinery
• [x] Instead of stop(), have _scheme return http and _is_tls_enabled return False until the cert is in place.

Depends on:

• https://github.com/canonical/prometheus-rock/pull/30 (https://github.com/canonical/oci-factory/pull/58)

Fixes https://github.com/canonical/prometheus-k8s-operator/issues/521

Testing Instructions

• Run itests in https://github.com/canonical/cos-lite-bundle/pull/80
• Manually test with the following bundles

bundle: kubernetes
applications:
  ca:
    charm: self-signed-certificates
    channel: edge
    scale: 1
  prom:
    charm: ./prometheus-k8s_ubuntu-20.04-amd64.charm
    series: focal
    scale: 1
    trust: true
    resources:
        prometheus-image: ghcr.io/canonical/prometheus:dev
relations:
- - ca:certificates
  - prom:certificates

bundle: kubernetes
applications:
  ca:
    charm: self-signed-certificates
    channel: edge
    scale: 1
  cat:
    charm: catalogue-k8s
    channel: edge
    series: focal
    scale: 1
  prom:
    charm: ./prometheus-k8s_ubuntu-20.04-amd64.charm
    series: focal
    scale: 1
    trust: true
    resources:
        prometheus-image: ghcr.io/canonical/prometheus:dev
  trfk:
    charm: traefik-k8s
    channel: edge
    series: focal
    scale: 1
relations:
- - cat:catalogue
  - prom:catalogue
- - ca:certificates
  - prom:certificates
- - prom:ingress
  - trfk:ingress-per-unit
- - trfk:certificates
  - ca:certificates

Release Notes

Fix handling of tls config.

[sed-i]

@PietroPasotti, check-libs complains:

Library charms.tempo_k8s.v0.charm_tracing has local changes, cannot be updated.

Haven't checked but might be a LIBPATCH bump issue.

[PietroPasotti]

@PietroPasotti, check-libs complains:

Library charms.tempo_k8s.v0.charm_tracing has local changes, cannot be updated.

Haven't checked but might be a LIBPATCH bump issue.

given https://github.com/canonical/prometheus-k8s-operator/pull/523 , the lib should be up to date? If the issue persists we could try deleting it manually and re-fetching it? Maybe the linter did some minor change to it?