This guide explains how to deploy a sample application using Flux GitOps. It demonstrates creating a simple NGINX application and testing it with MetalLB.

Prerequisites

  1. MetalLB Installed: Ensure MetalLB is installed and configured in your Kubernetes cluster.
  2. Flux Installed: Ensure Flux is installed and running in your Kubernetes cluster.
  3. Git Repository: A Git repository structured for Flux GitOps, e.g.,
    .
├── apps/
│   └── nginx-test/
│       └── base/
├── clusters/
│   └── production/
│       ├── apps/
<...>

1. Deploy a Sample Application

Step 1: Create the Application Manifest

File: apps/nginx-test/base/nginx-test.yaml:

# File: apps/nginx-test/base/nginx-test.yaml
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:1.21
          ports:
            - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-service
  namespace: default
spec:
  selector:
    app: nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
  type: LoadBalancer

File: apps/nginx-test/base/kustomization.yaml:

# File: apps/nginx-test/base/kustomization.yaml
---
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - nginx-test.yaml

Step 2: Reference the Application in Flux

Add the application to clusters/production/apps/kustomization.yaml:

# File: clusters/production/apps/kustomization.yaml
---
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  # ...existing resources...
  - ../../../apps/nginx-test/base

Commit and push the changes:

git add clusters/production/apps/kustomization.yaml
git commit -m "Add nginx-test application reference"
git push

2. Verify Deployment

Step 1: Check Flux Kustomizations

Ensure the nginx-test application is deployed:

kubectl get kustomizations -A

Step 2: Verify the Application

Check the nginx deployment and service:

kubectl get deployments -n default
kubectl get svc -n default

The nginx-service should show an EXTERNAL-IP assigned by MetalLB:

NAME            TYPE           CLUSTER-IP       EXTERNAL-IP      PORT(S)        AGE
nginx-service   LoadBalancer   10.103.0.231     xxx.xxx.xxx.90     80:31568/TCP   2m

Step 3: Test the Service

Access the service using the assigned EXTERNAL-IP:

  1. Using curl:
    curl http://<EXTERNAL-IP>
# e.g. curl http://xxx.xxx.xxx.90
  2. Using a browser:
    http://<EXTERNAL-IP>

You should see the default NGINX welcome page.

3. Cleanup

To remove the nginx-test application:

  1. Delete the apps/nginx-test directory and its references in clusters/production/apps/kustomization.yaml.
  2. Commit and push the changes:
    git commit -m "Remove nginx-test application"
git push

Flux will automatically clean up the application from the cluster.