Transform a Deployment to a Rollout

Argo Rollouts needs a Rollout resource to know what strategy to apply when rolling out a new version (canary or blue-green). When you are migrating a Deployment to a Rollout to change your deployment strategy, you can reference an existing Deployment since Argo Rollouts v1.0.0. When doing this operation, you should proceed as follows:

1. Create a Rollout resource.
2. Reference an existing Deployment using the workloadRef field.
3. Apply the new Rollout resource in your cluster.
4. Scale-down the existing Deployment by changing the replicas field to zero.
5. To perform future updates of your pod specs, the change should be made to the Pod template field of the Deployment.

Here is an example of a new Rollout manifest:

apiVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
  name: my-rollout
spec:
  replicas: 5
  workloadRef:
    apiVersion: apps/v1
    kind: Deployment
    name: my-deployment
  strategy:
    canary:
      steps:
        - setWeight: 20
        - pause: {duration: 10s}

And the changes that should be brought to the existing Deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-deployment
spec:
- replicas: 5
+ replicas: 0