Implementing GitOps with Argo CD and Azure DevOps: A Step-by-Step Tutorial

GitOps has revolutionized how we manage Kubernetes clusters by treating infrastructure as code and using Git as the single source of truth. While many tutorials focus on GitHub Actions or GitLab, many enterprises rely on Azure DevOps.

In this tutorial, we’ll walk through setting up a robust GitOps workflow using Azure Repos, Azure Pipelines, and Argo CD.

The Architecture

Our pipeline will follow the standard GitOps separation of concerns:

1. Application Repo: Contains the source code and a Dockerfile.
2. Manifest Repo: Contains Kubernetes manifests (Helm charts or Kustomize).
3. Azure Pipelines: Handles CI (building and pushing images).
4. Argo CD: Handles CD (synchronizing the Manifest Repo to the cluster).

Step 1: Preparing Azure DevOps

1.1 Create the Repositories

Create two repositories in your Azure DevOps project: my-app and my-app-gitops.

1.2 Create a Personal Access Token (PAT)

Argo CD needs a PAT to read the my-app-gitops repository. Ensure it has "Code: Read" permissions.

Step 2: Setting up Argo CD

Assuming you have Argo CD installed in your cluster, add your Azure Repo:

argocd repo add https://dev.azure.com/your-org/your-project/_git/my-app-gitops \
    --username internal-bot \
    --password <YOUR-PAT>

Step 3: The CI Pipeline (Azure Pipelines)

Your CI pipeline in my-app should do two things: build the image and update the tag in the GitOps repo.

1# azure-pipelines.yml snippet
2steps:
3- task: Docker@2
4  inputs:
5    command: buildAndPush
6    repository: my-app
7    tags: $(Build.BuildId)
8
9- script: |
10    git config --global user.email "devops@codingprotocols.com"
11    git config --global user.name "Azure Pipeline"
12    git clone https://$(PAT)@dev.azure.com/org/proj/_git/my-app-gitops
13    cd my-app-gitops
14    sed -i "s/tag: .*/tag: $(Build.BuildId)/" values.yaml
15    git add .
16    git commit -m "Update image tag to $(Build.BuildId)"
17    git push
18  displayName: 'Update GitOps Manifest'

Step 4: Configuring the Argo CD Application

Create the Application resource in Kubernetes (or via the Argo UI):

1apiVersion: argoproj.io/v1alpha1
2kind: Application
3metadata:
4  name: my-app
5  namespace: argocd
6spec:
7  project: default
8  source:
9    repoURL: 'https://dev.azure.com/your-org/your-project/_git/my-app-gitops'
10    targetRevision: HEAD
11    path: charts/my-app
12  destination:
13    server: 'https://kubernetes.default.svc'
14    namespace: prod
15  syncPolicy:
16    automated:
17      prune: true
18      selfHeal: true

Why This Works

By using this setup, you gain:

• Auditability: Every change to production is recorded in Git.
• Rollbacks: Want to revert? Just git revert the last commit in the GitOps repo.
• Security: The CI system doesn't need cluster-admin access. It only needs to push to Git.

Conclusion

Integrating Argo CD with Azure DevOps provides a powerful, enterprise-grade GitOps experience. It bridges the gap between Microsoft's ecosystem and the cloud-native world of Kubernetes.

Struggling with complex CI/CD migrations? Coding Protocols can help you design and implement production-ready GitOps workflows tailored to your stack.