2020-06-24: Unusual logs from pgbouncer

/label incident IncidentActive

Summary

After a reboot, pgbouncer-01 in production could not resolve the master patroni node with DNS.

Unusual logs from pgbouncer

Possible pgbouncer problems? Investigating.

Timeline

All times UTC.

2020-06-24

  • 21:54 - SRE announces in #production channel that they are seeing something weird that then went away:
$ sudo gitlab-rails console
Traceback (most recent call last):
	85: from bin/rails:4:in `<main>'
<elided>
	 3: from /opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql_adapter.rb:46:in `postgresql_connection'
	 2: from /opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/pg-1.2.2/lib/pg.rb:58:in `connect'
	 1: from /opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/pg-1.2.2/lib/pg.rb:58:in `new'
/opt/gitlab/embedded/lib/ruby/gems/2.6.0/gems/pg-1.2.2/lib/pg.rb:58:in `initialize': ERROR:  pgbouncer cannot connect to server (PG::ConnectionBad)
  • 22:03 - Another SRE notes that they are seeing errors in the pgbouncer logs
  • 22:16 - cmcfarland declares incident in Slack using /incident declare command.
  • 22:?? - pgbouncer service is identified to be doing little to no real work, so it is restarted
  • 22:?? - the error messages went away and pgbouncer started to show signs of performing work

Click to expand or collapse the Incident Review section.

Incident Review

Summary

  1. Service(s) affected:
  2. Team attribution:
  3. Minutes downtime or degradation:

Metrics

Customer Impact

  1. Who was impacted by this incident? (i.e. external customers, internal customers)
  2. What was the customer experience during the incident? (i.e. preventing them from doing X, incorrect display of Y, ...)
  3. How many customers were affected?
  4. If a precise customer impact number is unknown, what is the estimated potential impact?

Incident Response Analysis

  1. How was the event detected?
  2. How could detection time be improved?
  3. How did we reach the point where we knew how to mitigate the impact?
  4. How could time to mitigation be improved?

Post Incident Analysis

  1. How was the root cause diagnosed?
  2. How could time to diagnosis be improved?
  3. Do we have an existing backlog item that would've prevented or greatly reduced the impact of this incident?
  4. Was this incident triggered by a change (deployment of code or change to infrastructure. If yes, have you linked the issue which represents the change?)?

5 Whys

Lessons Learned

Corrective Actions

Guidelines

Edited by Cameron McFarland