Add logging during setup process and ensure we're reacting to start hook

[mthaddon]

Overview

We need to react to the start event for _set_up_discourse rather than the install event, because if a container is restarted it won't get an install event.

Add logging to the _set_up_discourse method so it's easier to see at what point during the process this is failing. In production (likely due to poor disk IO related to https://bugs.launchpad.net/juju/+bug/1989004, still to be confirmed) we're seeing issues where if containers are restarted and we can end up with the set up process failing and so discourse never being started.

This only seems possible if we enter the _set_up_discourse method, relations are ready and we can connect to the container, but then somewhere later on in this same method we fail to complete the setup.

This should help us track down where that's happening.

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Managing Charm Complexity
• The documentation is generated using src-docs
• The documentation for charmhub is updated.
• The PR is tagged with appropriate label (urgent, trivial, complex)

[nrobinaubertin]

This is probably blocked by a dependency issue that I'm trying to solve here: #125

[arturo-seijas]

LGTM

[nrobinaubertin]

I have the same issue locally as https://github.com/canonical/discourse-k8s-operator/actions/runs/6632062737/job/18039459125#step:13:139

But not when I switch back to 'install' instead of 'start'

[github-actions]

Test coverage for 659472e

Name              Stmts   Miss Branch BrPart  Cover   Missing
-------------------------------------------------------------
src/charm.py        314     38     86     17    86%   127, 129, 138, 140, 148-149, 289->294, 456-457, 469-471, 476-477, 488-490, 495-496, 508-510, 515-516, 528-530, 556-558, 598->exit, 605-606, 608->exit, 614, 642-648, 674->exit, 688-689, 699->exit, 713
src/database.py      30      1      8      1    95%   56
-------------------------------------------------------------
TOTAL               344     39     94     18    87%

Static code analysis report

Run started:2023-10-25 16:29:44.576356

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 1831
  Total lines skipped (#nosec): 1
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):

[amandahla]

LGTM