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⚙️ CI/CD Essentials Guide
CI/CD (Continuous Integration and Continuous Delivery/Deployment) automates the process of building, testing, and releasing software. It increases development speed, quality, and reliability by reducing manual errors and enabling frequent, incremental changes.
🔁 What is CI/CD?
| Term | Description |
|---|---|
| CI (Continuous Integration) | Automating code integration into a shared repo with frequent builds and tests. |
| CD (Continuous Delivery) | Automatically prepares builds for release to production. Requires a manual approval step. |
| CD (Continuous Deployment) | Automatically releases every passing change to production without manual approval. |
🧱 Key CI/CD Pipeline Stages
-
Source Stage
- Triggered on code push, PR, or schedule
- Source: GitHub, GitLab, Bitbucket, etc.
-
Build Stage
- Compile code, resolve dependencies, generate artifacts
- Tools: Maven, Gradle, Webpack, Docker
-
Test Stage
- Unit tests, integration tests, end-to-end tests
- Frameworks: JUnit, Mocha, Cypress, PyTest
-
Artifact Stage
- Package and store built artifacts
- Tools: JFrog Artifactory, Nexus, GitHub Packages
-
Deploy Stage
- Deploy to staging, QA, or production
- Tools: ArgoCD, Helm, Terraform, Kubernetes, Ansible
-
Post-deployment
- Smoke tests, rollback triggers, observability
🛠️ Common CI/CD Tools
| Function | Tools |
|---|---|
| Version Control | Git, GitHub, GitLab |
| CI Runners | GitHub Actions, GitLab CI, CircleCI, Jenkins |
| Artifact Repos | Nexus, JFrog Artifactory |
| Container Build | Docker, BuildKit, Kaniko |
| Deploy Automation | ArgoCD, Flux, Helm, Terraform |
| Monitoring | Prometheus, Grafana, New Relic |
🔐 Security in CI/CD
- Scan dependencies for vulnerabilities (
Snyk,Trivy) - Use secrets management (e.g. HashiCorp Vault, GitHub Secrets)
- Validate infrastructure code (Terraform, Kube configs)
- Enforce code reviews and signed commits
- Use isolated runners and limit permission scopes
🚨 CI/CD Best Practices
✅ Keep pipelines fast (< 10 minutes)
✅ Run tests early and in parallel
✅ Automate rollback and recovery
✅ Promote from staging → prod
✅ Use immutable artifacts
✅ Enforce linting and style checks
✅ Version your CI/CD config (YAML)
✅ Don't hardcode secrets or credentials
🔄 Deployment Strategies
| Strategy | Description | Use Case |
|---|---|---|
| Rolling Update | Gradually replace old with new pods | Most common with K8s |
| Blue-Green | Deploy to idle environment, switch | Low-risk, easy rollback |
| Canary | Deploy to small % of users, then all | Feature testing, risk mitigation |
| GitOps | Use Git as source of truth | Declarative infra & apps |
🧪 Testing in CI/CD
| Test Type | What it Checks | Stage |
|---|---|---|
| Unit Test | Individual function logic | Early (CI) |
| Integration Test | Module interaction | Mid (CI) |
| End-to-End (E2E) | App behavior as user | Late (CD) |
| Smoke Test | Basic sanity checks post-deploy | Deploy/CD |
| Load/Perf Test | Scale, latency, throughput | CD or Prod |
🌐 Infrastructure-as-Code (IaC)
Automate your infrastructure deployments using:
- Terraform, Pulumi – For provisioning
- Helm, Kustomize – For Kubernetes manifests
- Dockerfiles – For container builds
- Ansible, Chef – For configuration management
🔍 Observability & Monitoring
After deployment, monitor:
- 📈 Metrics (CPU, latency, error rate)
- 📋 Logs (stdout, error logs, app logs)
- 🔔 Alerts (PagerDuty, Slack, Opsgenie)
- 🎯 Tracing (OpenTelemetry, Jaeger)
📚 Further Learning Resources
✅ CI/CD Essentials Cheat Sheet
| Component | Example Tool |
|---|---|
| CI Trigger | GitHub Actions |
| Build | Docker, Gradle |
| Test | Jest, JUnit, Cypress |
| Package | GitHub Packages |
| Deploy | ArgoCD, Helm |
| Secrets Mgmt | Vault, AWS Secrets |
| Monitoring | Prometheus, Grafana |
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