Speed up bootstrap

[marceloneppel]

Issue

The PostgreSQL charm takes 9-10 minutes to start (be in an Active state).

Solution

• Avoid the legacy upgrade code execution during the start process (because it's not needed while Patroni is still offline).
• Tweak timeouts to avoid differing the events too early (if Patroni is still offline).
• Set the primary status message earlier.
• Add some debug logs of the time spent since the charm started until it reaches the Active state.
• Enabled and fixed a hidden unit test (test_set_primary_status_message). It was not being executed because of indentation in the test function.

Debug logs when using this PR charm (58 seconds from the beginning of the install hook until the workload is ready):

unit-postgresql-0: 19:27:23 DEBUG unit.postgresql/0.juju-log Install start time: 2024-06-24 19:27:23.462350
...
unit-postgresql-0: 19:28:21 DEBUG unit.postgresql/0.juju-log database-peers:1: Active workload time: 2024-06-24 19:28:21.274504

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.78%. Comparing base (dbd46b5) to head (0148f1e).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #413      +/-   ##
==========================================
+ Coverage   69.21%   69.78%   +0.56%     
==========================================
  Files          11       11              
  Lines        2865     2866       +1     
  Branches      507      507              
==========================================
+ Hits         1983     2000      +17     
+ Misses        781      761      -20     
- Partials      101      105       +4     

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[lucasgameiroborges]

LGTM! BTW sorry about the hidden unit test, that was probably me during the migration to pytest.

[taurus-forever]

The changes here really have positive effect on the start time.
Minimal changes which are promising! Thank you!

1 unit deployment:
23:48:28 - juju deploy
23:50:36 - the first event (lxc ready)
23:50:37 - Installing snap charmed-postgresql, revision 115, tracking 14/stable
23:51:08 - The snap installation completed successfully
23:51:58 - Completed.

3 units is a bit longer... but still good enough.

Let's move forward from here.

P.S. I am surprised to see no 503 Patroni API responces.

P.P.S. the datetime.now() is only necessary on CI/CD, as it duplicated juju debug-log timing:

unit-postgresql-4: 00:20:07 DEBUG unit.postgresql/4.juju-log Install start time: 2024-06-24 22:20:07.010192
unit-postgresql-4: 00:20:59 DEBUG unit.postgresql/4.juju-log Active workload time: 2024-06-24 22:20:59.474757

Anyway LGTM as it is WAY better the the current edge. Thank you!

[taurus-forever]

I am merging this to test beta and promote candidate for Mohamed.