Add Synapse Stats Exporter

[amandahla]

Overview

In order to collect and monitor the number of users and rooms in the Synapse instance, this PR install the synapse-stats-exporter so the metrics can be extracted by Prometheus.

Also, it refactors how the charm handle the admin_access_token.

Before the refactor, the admin access token was handled only by the charm and used by Mjolnir.

But since the Stats Exporter needs it too, it was complex to let this in the charm instead of letting the Synapse module handle it.

So what happens now?

• start event is emitted meaning that (hopefully) the workload was started (not just the container)

• If the admin access token already exists (as a secret or as peer data), start the Stats Exporter and return

• If the admin access token doesn't exist, create it via create_admin_user and save it in the charm_state

• Mjolnir and Stats Exporter will get the admin_access_token via charm_state

• Also, Mjolnir will create the user using the create_user available in the synapse module instead of calling actions.register_user (that didn't make much sense)

This is how the modules depend on each other now:

Rationale

Collect Synapse statistics.

Juju Events Changes

N/A

Module Changes

Pebble module has a new layer.

Library Changes

N/A

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Manging 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)

Documentation should be updated after the exporter being available.

[merkata]

Good start, left some minor comments, interested to see the tests on this.

[merkata]

Doesn'g mjolnir require an access token as well? Should it be added here?

[amandahla]

Yes, Mjolnir requires it too.

• If Mjolnir is enabled, the charm will instantiate a Mjolnir class passing state as parameter
• The class observes the collect status event that will check for the requirements and enable Mjolnir when everything is set

[merkata]

That error can be reworked now due to the change.

[amandahla]

Right now if the admin access token is None, the charm will be put on MaintenanceStatus. Do you think it should be changed?

self._charm.unit.status = ops.MaintenanceStatus(
"Failed to get admin access token. Please, check the logs."
)

[github-actions]

Test coverage for 53d1097

Name                            Stmts   Miss Branch BrPart  Cover   Missing
---------------------------------------------------------------------------
src/actions/__init__.py             3      0      0      0   100%
src/actions/register_user.py       19      1      2      1    90%   70
src/actions/reset_instance.py      21      0      2      0   100%
src/backup.py                      48      0      4      0   100%
src/backup_observer.py             35      0      2      0   100%
src/charm.py                      235     12     56      5    94%   164-165, 216-217, 244-245, 249-250, 253-254, 310-311
src/charm_state.py                 64      1     10      1    97%   129
src/charm_types.py                 23      0      6      0   100%
src/database_client.py             53      1     10      3    94%   35, 47->exit, 69->exit
src/database_observer.py           48      4      4      0    92%   69-71, 87
src/exceptions.py                   4      1      0      0    75%   22
src/mjolnir.py                     78      8     22      2    88%   59-63, 72, 164-165
src/observability.py                9      0      0      0   100%
src/pebble.py                     108     13     18      7    84%   84, 107-108, 110-111, 119, 121, 123, 127, 148-149, 164-165
src/saml_observer.py               45      1      8      0    98%   64
src/smtp_observer.py               70      3     14      1    95%   70-74, 96->101
src/synapse/__init__.py             4      0      0      0   100%
src/synapse/admin.py               20      2      2      0    91%   39-40
src/synapse/api.py                161      2     22      2    98%   207, 376
src/synapse/workload.py           272      8     42      6    96%   405->exit, 434-435, 487-488, 524-525, 541, 590->593, 639, 647->649, 649->651
src/user.py                        24      0      4      0   100%
---------------------------------------------------------------------------
TOTAL                            1344     57    228     28    94%

Static code analysis report

Run started:2024-02-01 16:06:06.236358

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 7039
  Total lines skipped (#nosec): 4
  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]

I'm closing this PR in favor of splitting the changes into smaller ones. This is already too messy.