Question

Are deployments with more than one replica automatically doing rolling updates when a new deployment config is applied

Answer 1

• The Deployment updates Pods in a rolling update fashion when .spec.strategy.type==RollingUpdate .

• You can specify maxUnavailable and maxSurge to control the rolling update process. 

• Rolling update is the default deployment strategy.kubectl rolling-update updates Pods and ReplicationControllers in a similar fashion. 

• But, Deployments are recommended, since they are declarative, and have additional features, such as rolling back to any previous revision even after the rolling update is done.

• So for rolling updates to work as one may expect, a readiness probe is essential. Redeploying deployments is easy but rolling updates will do it nicely for me without any downtime. 

• The way to make a  rolling update of a Deployment and kubctl apply on it is as below

spec:
minReadySeconds: 180
replicas: 9
revisionHistoryLimit: 20
selector:
matchLabels:
deployment: standard
name: standard-pod
strategy:
rollingUpdate:
maxSurge: 1
maxUnavailable: 1
type: RollingUpdate