Kubernetes in DevOps Pipelines

Introduction

In a modern cloud-native organization, developers should rarely run kubectl apply manually against a production cluster. Instead, Kubernetes deployments should be fully automated through Continuous Integration and Continuous Deployment (CI/CD) pipelines.

The Traditional Push Model (CI/CD)

In a traditional push-based pipeline (using tools like Jenkins, GitHub Actions, or GitLab CI):

1. A developer pushes code to GitHub.
2. The CI pipeline runs unit tests.
3. If tests pass, the pipeline builds a Docker image and pushes it to a registry.
4. The CD pipeline connects to the Kubernetes API server (using a Service Account token) and runs kubectl apply or helm upgrade to deploy the new image.

While this works, it requires giving your CI server administrative credentials to your production Kubernetes cluster, which is a major security risk.

The GitOps Pull Model (ArgoCD / Flux)

The modern best practice for Kubernetes is GitOps.

In GitOps, the Kubernetes cluster pulls changes from Git, rather than the CI server pushing changes to the cluster.

1. You store all your Kubernetes YAML files (or Helm charts) in a dedicated Git repository.
2. An operator running inside the Kubernetes cluster (like ArgoCD or Flux) continuously monitors the Git repository.
3. When you merge a PR updating a YAML file, ArgoCD detects the change and automatically syncs the cluster state to match the Git state.

This removes the need to store cluster credentials outside the cluster and provides a perfect audit trail (Git history) of every change made to production!

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