Multi-Region CD

Deploy across regions safely.

Why multi-region CD

Single-region deploys assume customers are in one region. Multi-region apps need region-aware deploys.

Naive parallel deploy: all regions at once. A bug hits all customers simultaneously.

Sequenced multi-region deploys reduce blast radius.

Region sequencing

Smallest region first. Catches obvious breakage with less impact.

Wait for SLO checks to pass between regions. 30-60 minutes of soak time.

Largest region last. By the time you reach it, the deploy has been validated.

Global state coordination

Database migrations are tricky. Schema changes must be backward-compatible across regions during the deploy window.

Two-phase migrations: forward-compatible deploy first, then schema change, then code that uses the schema.

Avoid multi-region coordinated migrations when possible. Decouple via dual-write or schema versioning.

Automate the sequence

Spinnaker, Argo Rollouts, custom CD systems all support region-by-region pipelines.

Per-region SLO check between stages. Auto-pause on regression.

Auto-rollback on the failed region; pause subsequent regions until investigated.

How to roll out

Start with two regions: smallest and largest. Get the pattern right.

Add regions to the sequence as you grow. Avoid 10-region pipelines until needed.

Document the pause-and-resume runbook. Operators will need it during incidents.