CircleCI CI/CD
Cloud CI/CD with .circleci/config.yml, orbs, and parallelism.
CI/CDIntermediate
Why
CircleCI offers fast builds with Docker support, orbs (reusable packages), and parallelism. Good for teams wanting managed CI without infrastructure.
DORA's 2024 State of DevOps report shows elite teams deploy 973x more frequently than low performers. CI/CD pipelines with automated testing reduce change failure rate to 5-15% versus 40-60% for manual deployments.
When
Use CircleCI for managed CI with good Docker support. Avoid for cost-sensitive (free tier limited).
How
1. Config — .circleci/config.yml
2. Orbs — reusable packages (node, aws, gcp)
3. Executor — docker, machine, or macos
4. Workflow — jobs with requires
5. Cache — restore_cache/save_cache
6. Parallel — parallelism for test split
7. Context — shared secrets
Example
# .circleci/config.yml
version: 2.1
orbs: { node: circleci/[email protected] }
jobs:
test:
docker: [{ image: cimg/node:20.0 }]
steps:
- checkout
- node/install-packages
- run: npm test
deploy:
docker: [{ image: cimg/node:20.0 }]
steps:
- checkout
- run: npx vercel --prod --token $VERCEL_TOKEN
workflows:
version: 2
build-test-deploy:
jobs:
- test
- deploy:
requires: [test]
filters: { branches: { only: [main] } }
Common Problems
- ⚠Build slow — no cache, use restore_cache/save_cache for deps
- ⚠Out of credits — free tier limited, parallelism uses credits fast
- ⚠Configuration drift between environments — use infrastructure-as-code (Terraform/Pulumi) to keep dev/staging/prod identical
Best Practices
- ✓Use orbs for common tasks — node, aws, gcp orbs save config
- ✓Use parallelism for test split — splits tests across executors for speed
- ✓Set up health checks and graceful shutdown — handle SIGTERM to drain in-flight requests before exit