What deployment strategies exist in Kubernetes?

In Kubernetes, there are several main deployment strategies that help update applications without downtime:

• Rolling Update — the standard update method where new pods are created gradually, and old ones are removed as the new ones become ready. This ensures continuous service operation.

• Recreate — all old pods are deleted first, then new ones are created. Used when it is not possible to run old and new versions simultaneously.

• Blue-Green Deployment — two environments (blue and green) are deployed. The new version runs in the "green" environment, and after verification, traffic is switched from "blue" to "green".

• Canary Deployment — the new version is launched on a small subset of pods to test stability, then gradually the share of the new version increases.

• A/B Testing — similar to canary, but with traffic split between different versions for testing.

Example of Rolling Update in a Deployment manifest:

spec:
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 1
      maxSurge: 1