KodeCloud CKAD Deployment Strategies

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Deployment Strategies¶

Deployment strategies:
- Recreate: Down time. All the older pods are destroyed first then the new ones are brought up.
- Rolling update: One by one. Default deployment strategy.

We deploy the new version (green) first and then direct the traffic to it.
This can be done easily by changing the label on the service to point to the pods of green deployment.

Only a small amount of traffic is sent to the new deployment.
If everything looks good then we replace the older deployment with the new one.
To implement in k8s we need to do 2 things:
- Route traffic to both the versions: This can be done by using a common label selector for both the deployments.
- Route only a small amount of traffic to version 2: This can be done by reducing the number of pods in the version 2 deployment.
  - This works since k8s service distributes the traffic equally between all the pods. It works on pods and not on deployments.
Code example:
The main issue with doing canary deployment in k8s is that the traffic is governed by the number of pods in each deployment.
- Service meshes like istio come with better control.
- With istio we can define the exact % of traffic to be distributed to each deployment.

Last updated: 2022-10-10