Kubernetes - Using Argo CD for Continuous Delivery

Introduction

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. It automates the deployment of applications to Kubernetes, ensuring that the desired state of your application matches the actual state of your Kubernetes clusters. This guide provides an overview of using Argo CD for continuous delivery in Kubernetes.

Installing Argo CD

To install Argo CD on a Kubernetes cluster, follow these steps:

# Create the namespace for Argo CD
kubectl create namespace argocd

# Install Argo CD using the official manifest
kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml

# Install the Argo CD CLI (macOS)
brew install argocd

# Access the Argo CD API server (use port-forwarding or an ingress resource)
kubectl port-forward svc/argocd-server -n argocd 8080:443

# Get the initial admin password
kubectl -n argocd get secret argocd-initial-admin-secret -o jsonpath="{.data.password}" | base64 --decode; echo
                

Accessing the Argo CD Dashboard

After installing Argo CD, you can access the Argo CD dashboard by navigating to https://localhost:8080 in your web browser. Use the username admin and the initial password retrieved in the previous step to log in.

Configuring Argo CD Applications

Argo CD manages applications using application definitions. These definitions specify the source repository, the target cluster, and the destination namespace. Here is an example of creating an Argo CD application:

# Create an application definition file (app.yaml)
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: my-app
  namespace: argocd
spec:
  destination:
    namespace: default
    server: https://kubernetes.default.svc
  source:
    path: my-app
    repoURL: https://github.com/myorg/my-repo.git
    targetRevision: HEAD
  project: default
  syncPolicy:
    automated:
      prune: true
      selfHeal: true

# Apply the application definition
kubectl apply -f app.yaml

# Sync the application using the Argo CD CLI
argocd app sync my-app

# Check the status of the application
argocd app get my-app
                

Using GitOps with Argo CD

Argo CD follows the GitOps model, where the desired state of applications is stored in Git repositories. Any changes to the Git repository are automatically applied to the Kubernetes cluster. This ensures that the Git repository is the single source of truth for your application deployments.

Advanced Features of Argo CD

Argo CD provides several advanced features to enhance the continuous delivery process:

• Automated Sync: Automatically sync the desired state from the Git repository to the Kubernetes cluster.
• Self-Healing: Automatically detect and correct any drift between the desired state and the actual state.
• Declarative Setup: Define Argo CD applications, projects, and settings using declarative YAML files.
• Multi-Cluster Support: Manage deployments across multiple Kubernetes clusters.
• RBAC: Implement role-based access control to manage user permissions.

Best Practices

Follow these best practices when using Argo CD for continuous delivery:

• Use Git as a Single Source of Truth: Store all application manifests and configurations in Git repositories.
• Automate Syncing: Enable automated syncing and self-healing to ensure that the desired state is always maintained.
• Use Declarative Configuration: Define all Argo CD applications and settings using declarative YAML files.
• Implement RBAC: Use role-based access control to manage permissions and ensure security.
• Monitor and Audit: Continuously monitor the state of your applications and audit changes for compliance.

Conclusion

This guide provided an overview of using Argo CD for continuous delivery in Kubernetes, including installing Argo CD, configuring applications, using GitOps, and following best practices. By leveraging Argo CD, you can automate the deployment process, ensure consistency between the desired and actual state of your applications, and enhance the overall reliability of your Kubernetes deployments.