Continuous Integration and Continuous Deployment automate the path from source code to a running application.
The fundamental idea is simple: every change should be validated automatically before it reaches production.
CI begins when a developer pushes code or creates a pull request.
A typical pipeline can:
If any stage fails, the change can be blocked before merging.
GitHub Actions represents workflows as YAML files stored inside the repository.
A workflow can respond to events such as:
This makes CI/CD part of the source-controlled project itself.
A good pipeline should run the same important checks that developers expect before merging.
For a TypeScript project this might include:
The pipeline should fail when important checks fail.
Dependency installation can become one of the slowest parts of a CI pipeline.
Caching package-manager data can dramatically reduce execution time.
The cache should be invalidated when dependency lockfiles change.
Production credentials should never be committed to source control.
GitHub Actions provides encrypted secrets that can be injected into workflows when required.
A strong principle is to provide a workflow with the minimum permissions and credentials necessary for its task.
A deployment workflow can automatically publish a successful build.
A common pattern is:
Code → Test → Build → Package → Deploy → Health Check
The health-check stage is important because a successful build does not guarantee a healthy application.
Deployment systems should also have a rollback strategy.
If a new release introduces a critical issue, reverting to a previously known-good version should be straightforward.
CI/CD is therefore not just automation. It is a reliability mechanism that makes software delivery repeatable and observable.