Table of Contents
- What is Continuous Delivery (CD)?
- Continuous Deployment vs. Continuous Delivery
- The Importance of CD in DevOps
- Key Components of a CD Pipeline
- Automating Deployment to Staging and Production
- CD Tools and Ecosystem
- Strategies for Safe and Reliable Releases
- Best Practices in CD
- Conclusion
What is Continuous Delivery (CD)?
Continuous Delivery is a DevOps practice where software is built in a way that allows it to be released to production at any time, reliably and automatically.
The main objective is to ensure that:
- Your code is always in a deployable state
- Every code change that passes CI can be deployed
- Manual processes like approvals are the only blockers to production release
“Continuous Delivery is the ability to get changes of all types — features, configuration, bug fixes — into production safely and quickly in a sustainable way.” — Jez Humble
Core Characteristics:
- Frequent, incremental updates
- Automation of all build → test → deploy steps
- Zero-downtime deployment strategies
Continuous Deployment vs. Continuous Delivery
These two terms are often confused but differ in intent:
| Aspect | Continuous Delivery | Continuous Deployment |
|---|---|---|
| Final Production Push | Manual trigger (often approval-based) | Fully automated |
| Focus | Ready for release at any moment | Automatically release every passing build |
| Control | High | Low |
| Use Case | Regulated industries, enterprise apps | SaaS platforms, startups, internal tools |
CD = Deliver any time.
Continuous Deployment = Deliver every time.
The Importance of CD in DevOps
DevOps is built around the automation of the software delivery lifecycle (SDLC), and CD is one of its most powerful enablers.
Benefits:
- Faster time-to-market
- Lower risk of release failure
- Higher code quality through frequent iterations
- Streamlined feedback loops
- Improved collaboration across dev, QA, and ops
With CD, you eliminate the “it works on my machine” problem by testing and deploying in production-like environments regularly.
Key Components of a CD Pipeline
- Source Code Repository
- The single source of truth (e.g., Git)
- CI Pipeline Output
- Builds, unit tests, artifacts from CI flow
- Staging Environment
- Mirror of production for validation
- Deployment Automation Scripts
- Shell scripts, Terraform, Helm charts, etc.
- Deployment Orchestrators
- Tools that handle rolling updates, canary releases, etc. (e.g., ArgoCD, Spinnaker)
- Observability and Monitoring
- Logs, metrics, and APM tools (e.g., Prometheus, Grafana)
- Approval Gates (Optional)
- Manual intervention steps before production
Automating Deployment to Staging and Production
A fully automated CD setup typically involves two primary environments: staging and production.
1. Staging Deployment
This environment mimics production:
- Same cloud provider or on-prem infrastructure
- Same configurations (DB, scaling, feature flags)
- Deployed automatically after passing CI
Sample with GitHub Actions:
yamlCopyEditdeploy-staging:
needs: build
runs-on: ubuntu-latest
steps:
- name: Checkout code
uses: actions/checkout@v3
- name: Deploy to Staging Server
run: ./scripts/deploy-staging.sh
2. Production Deployment
Triggered manually (for Continuous Delivery) or automatically (for Continuous Deployment).
Example (Manual Approval with GitLab):
yamlCopyEditdeploy_production:
stage: deploy
script:
- ./scripts/deploy-prod.sh
when: manual
only:
- main
Zero Downtime Considerations
- Blue/Green Deployments: Deploy to green, then switch traffic
- Canary Releases: Slowly release to a small % of users
- Feature Flags: Control functionality without changing code
CD Tools and Ecosystem
Popular CD orchestration tools and platforms include:
| Tool | Description |
|---|---|
| GitHub Actions | CI/CD for GitHub projects |
| GitLab CI/CD | End-to-end pipeline with auto deploys |
| Jenkins + Plugins | Highly customizable pipelines |
| ArgoCD | GitOps tool for Kubernetes deployment |
| Spinnaker | Release management and CD at scale |
| Flux | Kubernetes-native GitOps CD tool |
For infrastructure:
- Terraform (IaC for cloud resources)
- Helm (Kubernetes deployment templating)
Strategies for Safe and Reliable Releases
To avoid breaking production and ensure fast rollback:
1. Blue/Green Deployments
- Two identical environments
- Route traffic to the “green” version only when verified
2. Canary Releases
- Deploy to 5% of users → observe → ramp up
3. Rollbacks
- Scripts should allow automatic rollback on failure
- Maintain immutable infrastructure to support this
4. Feature Toggles / Flags
- Dynamically enable/disable features
- Decouple feature release from deployment
Best Practices in CD
| Practice | Description |
|---|---|
| Test thoroughly in staging | Ensure fidelity with production |
| Use secrets management | Never hardcode credentials |
| Implement access control | Not everyone should deploy |
| Monitor post-deployment | Use APM, logs, error tracking |
| Define rollback plans | Every deployment should have one |
| Document pipelines | Maintain shared understanding |
Conclusion
Continuous Delivery (CD) transforms your development pipeline from a code-writing process to a release-ready machine. With automation at its core and production safety in mind, CD enables:
- Frequent releases without fear
- Collaboration between devs and ops
- Fast user feedback for product iterations
In the next module, we’ll deep dive into Infrastructure as Code (IaC)—the foundation for repeatable, scalable environments that support CD.
