Module 5 · Reliability and the public internet Lesson 14 of 15

Backups, rollback and zero-downtime deploy

Worked example

Deploying into a fresh release directory and repointing the symlink means the rollback is a single ln -sfn to the previous release.

Your practice task

Add a rollback step to your deploy script and practise it once on purpose.

Do this before moving on. Reading a solution teaches the shape of it; typing it teaches you.

Key takeaway

A deploy you cannot undo is a deploy that will one day cost a weekend. Keep the last good release on disk, keep a database backup, and know the one command that goes back.

Almost there

15 lessons left of 15

Finish every lesson to unlock the certificate. Each one ends in a practice task — do them and the final project brief writes itself.