Rolling Deployments

• Strategy to deploy a new version of an application without causing downtime.

• They work by creating a single instance of the new version of an application, then shutting off one instance of the old version until all instances have been upgraded

How to:

1. Create an instance of the new version of the backend

2. Wait until new copy is up ("healthy")

3. Delete an instance of the old version of the backend

4. If any instances of the old version still exist, go back to step 1

Benefits:

• Well supported

• No huge bursts

• Easily reverted

Cons:

• Speed (can be slow to run)

• API compatibility (Usually can be mitigated by making APIs backwards compatible)

Rolling deployments are relatively simple to understand, and generally well supported by orchestrators. If your users mind when you have downtime, it's an excellent fist step to adopt this strategy.