Demo Argo Rollout Canary

In this lesson we demonstrate how to perform a gradual release using the canary deployment model provided by Argo Rollouts. Argo Rollouts extends Kubernetes Deployments with more control over update behavior — enabling canary, blue-green, and progressive delivery strategies. The canary strategy routes a percentage of traffic to a new revision and increases that percentage in controlled steps with optional pauses for validation.

The image shows a webpage titled "Canary Deployment Strategy" from Argo Rollouts, discussing a method for gradually releasing a new software version. It includes an overview and table of contents on the right.

Rollout manifest (canary strategy) — overview

A Rollout manifest (kind: Rollout) looks like a Deployment but gives you fine-grained control of updates. Instead of replacing all pods at once, the canary strategy lets you increment traffic using setWeight steps and pause actions (timed or indefinite). Example Rollout (illustrative):

apiVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
  name: example-rollout
spec:
  replicas: 10
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:1.15.4
          ports:
            - containerPort: 80
  minReadySeconds: 30
  revisionHistoryLimit: 3
  strategy:
    canary:
      maxSurge: 25%
      maxUnavailable: 0
      steps:
        - setWeight: 10
          pause:
            duration: 1h
        - setWeight: 20
          pause: {} # pause indefinitely until manual promotion

Pause duration formats supported: seconds (10s), minutes (10m), hours (1h), or an empty object ({}) for an indefinite (manual) pause:

spec:
  strategy:
    canary:
      steps:
        - pause: { duration: 10s }  # 10 seconds
        - pause: { duration: 10m }  # 10 minutes
        - pause: { duration: 1h }   # 1 hour
        - pause: {}                 # pause indefinitely (manual promotion)

A pause: {} is an indefinite pause — the rollout will wait until you manually promote the next step (UI or kubectl argo rollouts promote). Plan for manual verification before continuing.

Blue-green (reference snippet)

For comparison, here is a sample blue-green configuration (used for preview/promotion workflows):

revisions: 3
strategy:
  blueGreen:
    activeService: active-service
    previewService: preview-service
    previewReplicaCount: 1
    autoPromotionEnabled: false
    prePromotionAnalysis:
      templates:
        - templateName: success-rate
          args:
            - name: service-name
              value: guestbook-svc.default.svc.cluster.local
    postPromotionAnalysis:
      templates:
        - templateName: success-rate
          args:
            - name: service-name
              value: guestbook-svc.default.svc.cluster.local

Applying the canary example from the repository

This repository contains a patterns/canary/ folder with rollout.yml and service.yml. Below are the manifests used in the demo. Initial rollout.yml (canary steps):

apiVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
  name: app-rollout
  namespace: canary
spec:
  replicas: 10
  selector:
    matchLabels:
      app: app-rollout
  template:
    metadata:
      labels:
        app: app-rollout
    spec:
      containers:
        - name: app
          image: siddharth67/app:v1
  strategy:
    canary:
      steps:
        - setWeight: 20
          pause: {}
        - setWeight: 40
          pause:
            duration: 1m
        - setWeight: 60
          pause:
            duration: 1m
        - setWeight: 80
          pause:
            duration: 1m

For demo speed we adjusted timed pauses to 10s so the rollout completes faster:

apiVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
  name: app-rollout
  namespace: canary
spec:
  replicas: 10
  selector:
    matchLabels:
      app: app-rollout
  template:
    metadata:
      labels:
        app: app-rollout
    spec:
      containers:
        - name: app
          image: siddharth67/app:v1
  strategy:
    canary:
      steps:
        - setWeight: 20
        - pause: {}
        - setWeight: 40
        - pause:
            duration: 10s
        - setWeight: 60
        - pause:
            duration: 10s
        - setWeight: 80
        - pause:
            duration: 10s

Commands to create the namespace and apply the manifests:

# create the canary namespace
kubectl create ns canary

# apply the rollout and service manifests
kubectl -n canary apply -f cgoa-demos/patterns/canary/

# confirm resources
kubectl -n canary get all

Expected simplified output after apply:

namespace/canary created
rollout.argoproj.io/app-rollout created
service/app-rollout-service created

# kubectl -n canary get all
NAME                                       READY   STATUS    RESTARTS   AGE
pod/app-rollout-76f479c6bf-251rz          1/1     Running   0          8s
... (other app-rollout pods)

NAME                                       TYPE       CLUSTER-IP     PORT(S)
service/app-rollout-service                NodePort   10.109.7.217   80:30797/TCP

NAME                                           DESIRED   CURRENT   READY
replicaset.apps/app-rollout-76f479c6bf         10        10        10

Argo Rollouts manages ReplicaSets and pods for Rollout resources. You will not see a Kubernetes Deployment for this workload — instead look for rollout.argoproj.io and ReplicaSets.

Inspecting Rollouts

List rollouts in the cluster or a specific namespace:

# list rollouts in the current namespace
kubectl get rollouts

# list rollouts in the canary namespace
kubectl get rollouts -n canary

Example output:

# kubectl get rollouts -n canary
NAME         DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
app-rollout  10        10        10           10          37s

Accessing the application and observing canary traffic

The Service exposes the app on a NodePort (e.g., 30797). In the demo we continuously polled the /app endpoint and printed the reported application version. Use this local script (adjust the port as necessary):

while true; do
  echo -n "$(date '+%H:%M:%S') - ";
  curl -s --max-time 1 http://localhost:30797/app 2>/dev/null |
  awk '{
    if ($0 ~ /Application Version:/) {
      if ($0 ~ /v1/) print "\033[34m" $0 "\033[0m";
      else if ($0 ~ /v2/) print "\033[33m" $0 "\033[0m";
      else print $0;
    } else print $0;
  }';
  sleep 1;
done

This output will show mostly v1 at first, then occasional v2 responses as the canary begins, then a growing mix of v2 as the setWeight increases, and finally all v2 once the rollout completes.

Promoting a new version (UI or CLI)

To promote a new revision, update the container image to v2 in the manifest and apply it (or use the UI). The Rollout will create a new revision and follow the configured canary steps:

A setWeight: 20 step means 2 of 10 pods will run v2 while 8 run v1.
If the first step contains pause: {}, the rollout will stop for manual promotion.
On manual promotion, the rollout proceeds to 40%, 60%, 80%, and finally 100% (with configured pauses).

Promote with the kubectl plugin:

# promote to the next step
kubectl argo rollouts promote <rollout-name>

# promote fully (skip intermediate steps)
kubectl argo rollouts promote --full <rollout-name>

Make sure the kubectl-argo-rollouts plugin is installed if you plan to promote from the CLI. Alternatively, use the Argo Rollouts UI.

The image shows the interface of Argo Rollouts, displaying a canary deployment strategy with various weighted steps and a successful revision summary.

Example progression (polling output):

17:45 - Application Version: v1
17:48 - Application Version: v2
17:51 - Application Version: v2
18:04 - Application Version: v1
18:14 - Application Version: v2
...
19:14 - Application Version: v2
19:29 - Application Version: v2

As you promote through higher setWeight steps, the frequency of v2 responses increases until all pods serve v2.

The image shows an Argo Rollouts dashboard for managing application rollout strategies, specifically using a canary deployment strategy. It displays steps with weight settings, a container selection, and revision details.

Rollbacks and stability

Argo Rollouts keeps a revision history and supports rollback to a previous revision if issues are detected during promotion. You can revert using the UI or the CLI to restore a stable revision. The UI highlights stable revisions and current status for easy rollback.

The image shows a software interface for managing application rollouts, displaying steps like setting weights and pauses, with revisions marked as stable or "No Pods".

Quick reference

Table: common pause durations and promotion commands

Topic	Example
Pause formats	`yaml<br>pause: { duration: 10s }` or `yaml<br>pause: {}`
Promote to next step	`kubectl argo rollouts promote <rollout-name>`
Promote fully	`kubectl argo rollouts promote --full <rollout-name>`

Summary of best practices

Use setWeight steps to route a specific percentage of traffic to a new revision.
Combine timed pauses (e.g., 10s, 1m) with indefinite pauses ({}) for manual verification.
Observe application metrics and logs during each pause before promoting.
Use the Argo Rollouts UI or kubectl-argo-rollouts plugin to promote, inspect, and roll back as needed.

Ensure Argo Rollouts CRDs and controller are installed in your cluster and install the kubectl-argo-rollouts plugin if you intend to promote or inspect rollouts from the CLI. See the Argo Rollouts installation guide for details.

Links and references

Argo Rollouts documentation: https://argoproj.github.io/argo-rollouts/
kubectl-argo-rollouts plugin installation: https://argoproj.github.io/argo-rollouts/installation/#kubectl-plugin
Kubernetes documentation: https://kubernetes.io/docs/

That’s all for now.

Introduction

GitOps Terminology

GitOps Principles

GitOps Patterns

Tooling

Related Practices

Demo Argo Rollout Canary

Rollout manifest (canary strategy) — overview

Blue-green (reference snippet)

Applying the canary example from the repository

Inspecting Rollouts

Accessing the application and observing canary traffic

Promoting a new version (UI or CLI)

Rollbacks and stability

Quick reference

Links and references

Watch Video

Practice Lab

​Rollout manifest (canary strategy) — overview

​Blue-green (reference snippet)

​Applying the canary example from the repository

​Inspecting Rollouts

​Accessing the application and observing canary traffic

​Promoting a new version (UI or CLI)

​Rollbacks and stability

​Quick reference

​Links and references

Watch Video

Practice Lab

Rollout manifest (canary strategy) — overview

Blue-green (reference snippet)

Applying the canary example from the repository

Inspecting Rollouts

Accessing the application and observing canary traffic

Promoting a new version (UI or CLI)

Rollbacks and stability

Quick reference

Links and references