GitOps: Automating Application Deployment with ArgoCD, Jenkins, Kustomize, and K3d

Here, we’ll explore how to set up a GitOps workflow using ArgoCD, Jenkins, Kustomize and K3d. This setup enables automated application deployment to Kubernetes environments with seamless management of multiple environments like dev and prod.

The accompanying repository can be found here: argocd-app.

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Repository Structure

The repository is organized as follows:

• app-ci-image/: Contains Dockerfile and Jenkins pipeline (Jenkinsfile) to build and push the application image to DockerHub.
• k8s-app-kustomize/: Contains Kustomize configurations for managing Kubernetes resources.
  • common/: Base resources shared across environments.
  • environments/: Overlays for specific environments (dev, prod).
• argocd-application-dev.yaml: Defines the ArgoCD application configuration for the development environment.
• argocd-application-prod.yaml: Defines the ArgoCD application configuration for the production environment.

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Prerequisites

To follow along, ensure you have the following:

• A Kubernetes cluster (e.g., K3d for local development).
• ArgoCD installed in the cluster.
• kubectl CLI installed locally.

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Setting Up the Environment

1. Clone the Repository

Start by cloning the repository:

git clone https://github.com/OpsMo/argocd-app.git
cd argocd-app

2. Build and Push the Application Image

Option 1: Manual Build

Navigate to the app-ci-image directory:

cd app-ci-image

Build and push the Docker image:

docker build -t your-repo/your-app:latest .
docker push your-repo/your-app:latest

Option 2: Jenkins Pipeline

Use the provided Jenkins pipeline to automate the process. The Jenkinsfile in the app-ci-image directory is preconfigured for this purpose:

• Configure Jenkins to use the pipeline script from SCM.
• Trigger the pipeline to build and push the image to DockerHub.

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Kustomize: Managing Multiple Environments

Common Directory (k8s-app-kustomize/common)

The common directory contains base resources that are shared across environments:

• deployment.yaml: Defines the base deployment for Nginx.
• nginx-service.yaml: ClusterIP service for Nginx.
• nginx-ingress.yaml: Configures ingress for routing traffic.
• kustomization.yaml: Lists the resources included in the base configuration.

Example kustomization.yaml:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- deployment.yaml
- nginx-service.yaml
- nginx-ingress.yaml

Environment-Specific Overlays (k8s-app-kustomize/environments)

Each environment (e.g., dev, prod) contains specific configurations:

Dev Directory

• kustomization.yaml: Includes the base resources and applies patches.
• deployment-dev.yaml: Adds environment variables for dev.
• ingress-dev.yaml: Customizes ingress paths for dev.

Example kustomization.yaml:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - ../../common
patches:
  - target:
      kind: Ingress
      name: nginx-ingress
    path: ingress-dev.yaml
  - target:
      kind: Deployment
      name: nginx
    path: deployment-dev.yaml
namespace: dev

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Configuring ArgoCD Application

The repository includes ArgoCD application manifests for dev and prod environments. Below is an example configuration for dev:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: my-app-dev
  namespace: argocd
spec:
  destination:
    namespace: dev
    server: https://kubernetes.default.svc
  project: default
  source:
    repoURL: https://github.com/OpsMo/argocd-app.git
    targetRevision: main
    path: k8s-app-kustomize/environments/dev
  syncPolicy:
    automated:
      prune: true
      selfHeal: true

To deploy :

kubectl apply -f argocd-application-dev.yaml -n argocd

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Access the Application:

Use ArgoCD’s UI or ku to monitor the deployment.

Once deployed, access the application via exposed service or configured ingress (K3d comes with Traefik controller)

for argocd-application-prod.yaml as well

Rollback with ArgoCD

Rollback to a previous version using ArgoCD CLI:

1. View the application history:

    argocd app history my-app-dev
   

2. Rollback to a specific revision:

    argocd app rollback my-app-dev --revision <revision-number>
   

3. Verify the rollback:

    argocd app get my-app-dev
   

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Best Practices

• GitOps Principles: Store all configurations in version control (Git) and use ArgoCD for syncing changes.
• Separate Environments: Manage dev and prod using Kustomize overlays.
• Automate CI/CD: Leverage Jenkins (or any other CI tools like Github actions) for consistent and automated image/artifact builds.

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Explore the Repository

Follow the repository to explore the complete project structure and configurations: argocd-app.

Goodluck😊