.NET Architecture & System Design Interview Question #177

What is a rolling deployment?

Deployment, Cloud Operations, SRE & Senior System Design Scenarios Senior Advanced

Quick Interview Answer

A rolling deployment replaces application instances gradually rather than stopping the entire fleet at once. During the rollout, old and new versions run simultaneously.

Detailed Explanation

A rolling deployment replaces application instances gradually rather than stopping the entire fleet at once. During the rollout, old and new versions run simultaneously.

Rolling deployments reduce downtime and infrastructure duplication, but adjacent versions must be compatible while they coexist. Database changes and shared contracts therefore require careful backward-compatible evolution.

Code Example

v1 v1 v1 v1
   |
v2 v1 v1 v1
   |
v2 v2 v1 v1
   |
v2 v2 v2 v2