Deploying PHP applications

with zero downtime

ConFoo, Montreal - February 23rd, 2023

© David Buchmann

David Buchmann - david@liip.ch

PHP Engineer, Liip AG, Switzerland

If you really have to, use FTP with TLS: SFTP

Upload your application

git pull / scp / rsync

Replacing files in place on the running system

Replace files in place

• OK to deploy to shared hosting or for small generated pages of static files
• Wordpress or Drupal applications are capable of operating without shell access
• Inconsistent while files are being uploaded
• Not really interruption free, certainly not robust
• Lets look at more powerful options

Goals for a deployment

• Minimize downtime
• Rollback on failure
• Repeatable deployments across environments
• Deploy early, deploy often

Automate everything!

• No manual mistakes
• Nothing gets forgotten
• Each step runs as soon as the previous is finished
• Running code is accurate documentation
• Version control everything, including deployment scripts
• Low effort to do a deployment

Deploy from CI

Have your CI run the deployments

• Guaranteed that no manual steps creep in
• Every team member can trigger a deployment
• Avoids differences between personal setup
• Clean state, no accidental changes deployed.
  Discourages manual hacks.
• Continous deployment
  Feature flags where necessary

Atomic deployment

• Uploading the files takes a time > 0
• Uploading can be interrupted in the middle
• You need your application's code to be consistent