<p>I have k8s setup that contains 2 deployments: client and server deployed from different images. Both deployments have replica sets inside, liveness and readiness probes defined. The client communicates with the server via k8s' service.</p>

<p>Currently, the deployment scripts for both client and server are separated (separate yaml files applied via kustomization). Rollback works correctly for both parts independently but let's consider the following scenario:
1. deployment is starting
2. both deployment configurations are applied
3. k8s master starts replacing pods of server and client
4. server pods start correctly so new replica set has all the new pods up and running
5. client pods have an issue, so the old replica set is still running</p>

<p>In many cases it's not a problem, because client and server work independently, but there are situations when breaking change to the server API is released and both client and server must be updated. In that case if any of these two fails then both should be rolled back (doesn't matter which one fails - both needs to be rolled back to be in sync).</p>

<p>Is there a way to achieve that in k8s? I spent quite a lot of time searching for some solution but everything I found so far describes deployments/rollbacks of one thing at the time and that doesn't solve the issue above.</p>

<p>The problem here is something covered in Blue/Green deployments. 
<a href="https://www.ianlewis.org/en/bluegreen-deployments-kubernetes" rel="nofollow noreferrer">Here</a> is a good reference of Blue/Green deployments with k8s.</p>

<p>The basic idea is, you deploy the new version (Green deployment) while keeping the previous version (Blue deployment) up and running and only allow traffic to the new version (Green deployment) when everything went fine.</p>
