Demo Health Check

In this lesson you’ll:

Create a namespace.
Deploy an Argo Rollout with a blue/green strategy.
Verify the application’s /health endpoint — suitable for use in an AnalysisTemplate and AnalysisRun to gate promotion.

The Rollout below (save as rollout-initial.yaml) runs five replicas of the “highway-animation” app (blue variant), sets a POD_COUNT environment variable, and configures blue/green with manual promotion (autoPromotionEnabled: false) so promotion can be done manually or via an analysis.

# rollout-initial.yaml
apiVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
  name: highway-bluegreen
  namespace: argo-analysis-lab
spec:
  replicas: 5
  selector:
    matchLabels:
      app: highway-bluegreen
  template:
    metadata:
      labels:
        app: highway-bluegreen
    spec:
      containers:
      - name: highway-bluegreen
        image: siddharth67/highway-animation:blue
        ports:
        - containerPort: 3000
        env:
        - name: POD_COUNT
          value: "5"
  strategy:
    blueGreen:
      activeService: highway-bluegreen-active
      previewService: highway-bluegreen-preview
      autoPromotionEnabled: false
---
apiVersion: v1
kind: Service
metadata:
  name: highway-bluegreen-active
  namespace: argo-analysis-lab
spec:
  type: NodePort
  selector:
    app: highway-bluegreen
  ports:
    - port: 80
      targetPort: 3000
      nodePort: 32079
---
apiVersion: v1
kind: Service
metadata:
  name: highway-bluegreen-preview
  namespace: argo-analysis-lab
spec:
  type: NodePort
  selector:
    app: highway-bluegreen
  ports:
    - port: 80
      targetPort: 3000
      nodePort: 31058

Create the namespace and apply the manifest:

# create namespace
kubectl create namespace argo-analysis-lab

# apply the rollout and services
kubectl -n argo-analysis-lab apply -f rollout-initial.yaml

Expected output after applying:

rollout.argoproj.io/highway-bluegreen created
service/highway-bluegreen-active created
service/highway-bluegreen-preview created

Verify pods and services in the namespace:

kubectl -n argo-analysis-lab get pods,svc

Example output (NodePort mappings shown):

NAME                                            READY   STATUS    RESTARTS   AGE
pod/highway-bluegreen-xxxxx                     1/1     Running   0          30s
pod/highway-bluegreen-xxxxx                     1/1     Running   0          30s
pod/highway-bluegreen-xxxxx                     1/1     Running   0          30s
pod/highway-bluegreen-xxxxx                     1/1     Running   0          30s
pod/highway-bluegreen-xxxxx                     1/1     Running   0          30s

NAME                                    TYPE       CLUSTER-IP      EXTERNAL-IP   PORT(S)            AGE
service/highway-bluegreen-active        NodePort   10.110.85.145   <none>        80:32079/TCP       30s
service/highway-bluegreen-preview       NodePort   10.108.197.140  <none>        80:31058/TCP       30s

Open the Argo Rollouts UI and switch to the argo-analysis-lab namespace to confirm the Rollout and blue/green details.

A screenshot of the Argo Rollouts web UI for the "highway-bluegreen" rollout showing a BlueGreen strategy, container image "siddharth67/highway-animation:blue", and a Revision 1 marked stable and active with green checkmarks. The top-right shows the namespace "argo-analysis-lab" and control buttons like Restart, Retry, Abort, and Promote.

Access the app via the active service NodePort on any cluster node: http://<node-ip>:32079 The application exposes a /health endpoint that returns a simple JSON payload:

{
  "status": "OK",
  "message": "Highway Animation Server is running"
}

This /health endpoint is a good target for an Argo Rollouts AnalysisTemplate. An AnalysisRun can query the endpoint and assert that "status" == "OK" before promoting the preview to active.

The Rollout is configured with autoPromotionEnabled: false. Promotion must be performed manually via the Argo Rollouts UI/CLI or gated using an AnalysisRun. Also be cautious exposing NodePorts in production clusters — prefer Ingress or LoadBalancer for controlled external access.

Resources at a glance:

Resource Type	Purpose
Rollout	Manages blue/green deployment of `highway-bluegreen` with 5 replicas and manual promotion.
Service (active)	NodePort service routed to the active replica set (port 32079).
Service (preview)	NodePort service routed to the preview replica set (port 31058).

Links and references:

Argo Rollouts blue/green traffic management: https://argoproj.github.io/argo-rollouts/features/traffic-management/#blue-green
Argo Rollouts analysis feature (AnalysisTemplate & AnalysisRun): https://argoproj.github.io/argo-rollouts/features/analysis/
Kubernetes documentation: https://kubernetes.io/docs/

That’s the health-check setup for this Rollout. You can now author an AnalysisTemplate that probes /health, run an AnalysisRun during promotion, and use its result to gate the transition from preview to active.

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Analysis Template and AnalysisRun

Demo AnalysisTemplate

ArgoCD

Argo Workflow

Argo Rollouts

Argo Events

Introduction

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