Run a canary rollout with Argo Rollouts

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Update a workload with a canary rollout and follow it in Lens K8S IDE. The new revision receives 20% of the traffic, waits for you to promote it, moves to 50%, and then takes all the traffic. For what each view and action shows, see Argo Rollouts.

What happens at each step

The table lists what you do and what the Rollouts list shows at each stage of the update. The two pauses are where the rollout waits: the first one for you, the second one for 30 seconds.

Stage	What you do	Status	Step	Weight
Rollout created	Apply the manifest	Healthy	4/4	100%
Set weight 20%	Change the image	Progressing	0/4	20%
Pause until promoted	Check the new revision, then select Promote	Paused	1/4	20%
Set weight 50%	Nothing	Progressing	2/4	50%
Pause 30s	Nothing	Paused	3/4	50%
Update done	Nothing	Healthy	4/4	100%

Set weight steps last only as long as the new pods take to start, so the list can skip from 1/4 to 3/4.

Before you begin

• The Argo Rollouts controller runs in the cluster. See the Argo Rollouts installation guide .
• The cluster is connected in Lens K8S IDE, and the Argo CD entry shows the Rollouts group. If it does not, disconnect and reconnect the cluster.
• Your Kubernetes role has the patch verb on rollouts and rollouts/status.

Create the rollout

1. Save this manifest as demo-canary.yaml:

   apiVersion: argoproj.io/v1alpha1
   kind: Rollout
   metadata:
     name: demo-canary
   spec:
     replicas: 5
     selector:
       matchLabels:
         app: demo-canary
     template:
       metadata:
         labels:
           app: demo-canary
       spec:
         containers:
           - name: demo
             image: argoproj/rollouts-demo:blue
             ports:
               - containerPort: 8080
     strategy:
       canary:
         steps:
           - setWeight: 20
           - pause: {}
           - setWeight: 50
           - pause: {duration: 30s}
   

   The four steps appear in Lens K8S IDE as Set weight 20%, Pause until promoted, Set weight 50%, and Pause 30s.

2. Apply it:

   kubectl apply -f demo-canary.yaml
   

   If Argo CD manages the namespace, commit the manifest to the Git repository of the Application instead, and let Argo CD sync it.

3. In the cluster navigator, select Argo CD > Rollouts > Rollouts. The demo-canary rollout shows Healthy, Step 4/4, and Weight 100%.

   

The first revision of a rollout becomes stable at once. The steps run from the next update.

Start the update

Change the image of the rollout to start a canary update:

kubectl patch rollout demo-canary --type json \
  -p '[{"op": "replace", "path": "/spec/template/spec/containers/0/image", "value": "argoproj/rollouts-demo:yellow"}]'

The controller creates a ReplicaSet for the new revision, sends it 20% of the traffic, and stops at the pause. In the Rollouts list, demo-canary shows Paused, Step 1/4, and Weight 20%.

The Argo CD dashboard lists the rollout under Needs attention as Awaiting promotion, at Step 1/4. A rollout that a user paused shows Paused instead.

Check the new revision

1. Select demo-canary to open its details panel.
2. In Steps, check that Set weight 20% is Done and Pause until promoted is Current.
3. In Revisions, check the pods of the canary revision next to the stable one.

Promote the rollout

1. Right-click demo-canary, or open its context menu.

2. Select Promote.

   

A notification reports Promoted rollout demo-canary. The rollout moves past the pause and sends 50% of the traffic to the new revision. During Pause 30s, the list shows Paused, Step 3/4, and Weight 50%. That pause ends without any action from you.

After the last step, the list shows Healthy, Step 4/4, and Weight 100%. In the details panel, every step is Done, and the new revision is stable with all the pods.

Abort the update

To stop the update at any step, select Abort from the rollout's menu and confirm. The new revision scales down, all traffic goes back to the stable revision, and Weight shows 0%. Select Retry to restart the update.

To skip the remaining steps instead, select Promote Full and confirm. The new revision becomes stable at once.

Clean up

kubectl delete rollout demo-canary

To discuss Argo Rollouts support for your organization, contact us.