How to migrate a server

Some initial preparation

• Drop DNS TTL down to 300
• Wait
• Drop DNS TTL down to 60

On source server

• Clear out some old backups in /backups to make room on disk (if necessary)
• Put discourse into read-only mode
• Write down discourse S3 credentials
• Do a manual backup of discourse
• Put first server into read-only maintenance mode
• Wait for background jobs to finish (or kill them if they're taking a long time)
• service morph-worker stop
• sudo su - deploy; cd /var/www/current; bundle exec rake app:backup RAILS_ENV=production
• Wait about 10 minutes

On destination server

• rsync root@[ip of source server]:/var/www/current/db/backups/morph_backup.tar . --progress
• service morph-worker stop
• service redis stop
• sudo su - deploy; cd /var/www/current; bundle exec rake app:restore RAILS_ENV=production
• Wait about 10 minutes
• service redis start
• service morph-worker start
• Check ownership on sqlite databases (they're probably going to be wrong)

On local machine (for testing)

• Edit /etc/hosts to add

[ip address of destination server]     morph.io
[ip address of destination server]     faye.morph.io
[ip address of destination server]     discuss.morph.io

• Switch off read-only mode on destination server
• Test that things work as expected by clicking around and running a scraper
• Fill in S3 credentials for discourse from earlier
• Do restore of discourse from backup
• Test some more
• sudo su - deploy; cd /var/www/current; bundle exec rake app:synchronise_repos RAILS_ENV=production

On DNS:

• Switch over to new ip address

Final updates:

• Activate cronjobs on new server (probably just provision with ansible)
• Switch off old server when everything is good
• Raise DNS TTL