Jenkins CI/CD

Jenkins is one of the most widely deployed CI/CD platforms in enterprise environments. It connects Git commits to automated builds, tests, artifact publishing, and staged production deployments.

Part of my Infrastructure learning notes.

What infrastructure engineers own

Component	Typical platform team responsibility
Jenkins controller	Installation, patching, backups, RBAC
Agents / build nodes	Capacity, labels, toolchains, disk monitoring
Credentials	Registry, SSH, kubeconfig, vault integration
Artifact registry	Container registry or Nexus/Artifactory access
Deploy targets	Network access, deploy users, rollback scripts
Pipeline standards	Shared libraries, approval gates, security scanning

Developers own application code and tests; platform teams make the pipeline reliable and safe.

End-to-end flow

git push → webhook → Jenkins controller → agent
    → checkout → test → build → scan → push artifact
    → deploy DEV → deploy staging → approve → deploy production

Core architecture

Component	Role
Controller	Schedules jobs, stores config, serves UI
Agent	Runs pipeline steps on labeled build nodes
Jenkinsfile	Pipeline-as-code in the repository
Shared library	Reusable deploy and notification steps
Credentials store	Secrets referenced by ID, never in Git

Common agent patterns

Permanent Linux VMs — stable toolchain for legacy builds
Docker agents — clean environment per build
Kubernetes agents — elastic scale for container-native teams
SSH agents — remote hosts already in the estate

How Jenkins connects to the stack

Ansible — configuration and deploy playbooks triggered from pipeline stages
Docker & Kubernetes — image build, registry push, and cluster rollout
Git — source control webhooks and Jenkinsfile versioning

Common issues (quick reference)

Webhook not firing — firewall, wrong URL, branch filters
Agent offline — label mismatch, SSH failure, full disk
Deploy permission denied — expired credentials or blocked agent IP
False-green deploy — shallow health checks, missing migrations
Plugin upgrade breaks pipelines — test on staging controller first

Full pipeline guide

The detailed walkthrough — including a complete Jenkinsfile, Ansible and Kubernetes deploy examples, security checklist, and expanded troubleshooting — is in the blog post:

Jenkins CI/CD: From Developer Push to Production Deployment