Gitter OS Patching (beta)
Summary
As an interim step towards updating Gitter AMI images (infrastructure#5755), follow-up to infrastructure#5492, and in support of production#620 (moved), we need to perform OS patching on all Gitter instances to establish timing and validate the steps listed in production#620 (moved).
Patch process
The patch process should at least be scripted, or possibly implemented via Ansible. The broad strokes will require running apt-get update && apt-get upgrade. On at least one instance, preferably one instance of each service/group, we will also need to script and validate the rollback process before proceeding to production. Finally, we need to consider service impact when orchestrating the change, by draining connections and detaching instances from load-balancer(s) wherever possible.