Use this skill when setting up CI/CD pipelines, configuring GitHub Actions, implementing deployment strategies, or automating build/test/deploy workflows. Triggers on GitHub Actions, CI pipeline, CD pipeline, deployment automation, blue-green deployment, canary release, rolling update, build matrix, artifacts, and any task requiring continuous integration or delivery setup.
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Use this skill when setting up CI/CD pipelines, configuring GitHub Actions, implementing deployment strategies, or automating build/test/deploy workflows. Triggers on GitHub Actions, CI pipeline, CD pipeline, deployment automation, blue-green deployment, canary release, rolling update, build matrix, artifacts, and any task requiring continuous integration or delivery setup.
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CI/CD Pipelines
A practitioner's guide to continuous integration and continuous delivery for
production systems. This skill covers pipeline design, GitHub Actions workflows,
deployment strategies, and the operational patterns that keep software shipping
safely at speed. The emphasis is on when to apply each pattern and why it
matters, not just the YAML syntax.
CI/CD is not a tool configuration problem - it is a software delivery
discipline. The pipeline is the product team's contract with production: every
commit that passes is a candidate release, and the pipeline enforces that
contract automatically.
When to use this skill
Trigger this skill when the user:
Creates or modifies a GitHub Actions, GitLab CI, or Jenkins pipeline
Implements PR checks, branch protection rules, or required status checks
Sets up deployment environments (staging, production) with promotion gates
Implements blue-green, canary, rolling, or recreate deployment strategies
Configures caching for dependencies or build artifacts to speed up pipelines
Sets up matrix builds to test across multiple Node versions or operating systems
Automates secrets injection, environment promotion, or rollback procedures
Diagnoses a slow pipeline and needs to find what to parallelize or cache
Do NOT trigger this skill for:
Infrastructure provisioning from scratch (use a Terraform/Kubernetes skill instead)
Application-level testing strategies unrelated to pipeline structure
Key principles
Fail fast - The pipeline should surface errors as early as possible.
Run linting and type-checking before tests. Run unit tests before integration
tests. A 30-second lint failure beats a 10-minute test run that tells you the
same thing.
Cache aggressively - node_modules, Maven .m2, pip wheels, and Docker
layer caches can turn a 12-minute pipeline into a 3-minute one. Cache by the
lockfile hash so the cache busts exactly when dependencies change.
Keep pipelines under 10 minutes - Pipelines longer than 10 minutes cause
developers to stop watching them, batch commits to avoid waiting, and skip
running them locally. Parallelize jobs, split slow test suites, and move
heavy analysis to scheduled runs.
Trunk-based development - Short-lived branches merged frequently (at
least daily) are the prerequisite for effective CI. Long-lived branches turn
CI into a lie - the code integrates in CI but not in reality.
Immutable artifacts - Build once, deploy everywhere. The same Docker
image or archive that passed staging must be the thing that goes to
production. Never rebuild from source at deploy time.
Core concepts
Pipeline stages run in order and each must pass before the next begins:
build -> test -> deploy:staging -> approve -> deploy:production
Triggers determine when a pipeline runs:
push on any branch - run build and test
pull_request - run full check suite for the PR
schedule (cron) - run security scans or long test suites nightly
workflow_dispatch - manual trigger with optional inputs for on-demand deploys
Environments are named targets (staging, production) with their own secrets,
protection rules, and deployment history. GitHub Environments let you require
manual approvals before promoting to production.
Secrets management - secrets live in GitHub Secrets or an external vault
(Vault, AWS Secrets Manager). They are injected as environment variables at
runtime. Never print them in logs. Rotate them on a schedule.
Artifact storage - build outputs (compiled code, Docker images, test
reports) are stored in GitHub Artifacts or a registry (GHCR, ECR, Docker Hub).
Artifacts have a retention window; images are tagged with the commit SHA.
Common tasks
Set up GitHub Actions for Node.js
A standard Node.js pipeline with lint, test, and build, using dependency caching:
# .github/workflows/ci.ymlname:CIon:push:branches: [main]
pull_request:jobs:ci:runs-on:ubuntu-lateststeps:-uses:actions/checkout@v4-uses:actions/setup-node@v4with:node-version:20cache:npm# caches ~/.npm by package-lock.json hash-run:npmci# clean install from lockfile-run:npmrunlint-run:npmtest----coverage-run:npmrunbuild-uses:actions/upload-artifact@v4with:name:distpath:dist/retention-days:7
Use npm ci instead of npm install in CI. It is faster, deterministic,
and will fail if package-lock.json is out of sync with package.json.
Implement PR checks
Require the CI workflow to pass before merging. Configure in GitHub Settings >
Branches > Branch protection rules:
Enable "Require status checks to pass before merging"
Add the job name (ci) as a required check
Enable "Require branches to be up to date before merging"
# .github/workflows/pr-check.ymlname:PRCheckon:pull_request:types: [opened, synchronize, reopened]
jobs:lint:runs-on:ubuntu-lateststeps:-uses:actions/checkout@v4-uses:actions/setup-node@v4with:node-version:20cache:npm-run:npmci-run:npmrunlinttest:runs-on:ubuntu-latestneeds:lint# only run tests if lint passessteps:-uses:actions/checkout@v4-uses:actions/setup-node@v4with:node-version:20cache:npm-run:npmci-run:npmtesttypecheck:runs-on:ubuntu-lateststeps:-uses:actions/checkout@v4-uses:actions/setup-node@v4with:node-version:20cache:npm-run:npmci-run:npmruntypecheck
Set up deployment environments with approvals
Use GitHub Environments to gate production deploys behind a manual approval:
Configure environment protection rules in GitHub Settings > Environments >
production > Required reviewers.
Implement blue-green deployment
Route traffic between two identical environments. Switch instantly; roll back
by switching back:
deploy-blue-green:runs-on:ubuntu-latestenvironment:productionenv:IMAGE_TAG:${{needs.build.outputs.image-tag}}steps:-uses:actions/checkout@v4-name:Determineinactiveslotid:slotrun:|
ACTIVE=$(curl -s https://api.example.com/active-slot)
if [ "$ACTIVE" = "blue" ]; then
echo "target=green" >> $GITHUB_OUTPUT
else
echo "target=blue" >> $GITHUB_OUTPUT
fi
-name:Deploytoinactiveslotrun:./scripts/deploy-slot.sh${{steps.slot.outputs.target}}$IMAGE_TAG-name:Runsmoketestsagainstinactiveslotrun:./scripts/smoke-test.sh${{steps.slot.outputs.target}}-name:Switchtraffictonewslotrun:./scripts/switch-slot.sh${{steps.slot.outputs.target}}-name:Verifyproductionishealthyrun:./scripts/health-check.shproduction-name:Rollbackonfailureif:failure()run:./scripts/switch-slot.sh${{steps.slot.outputs.target=='blue'&&'green'||'blue'}}
See references/deployment-strategies.md for a detailed comparison of
blue-green vs canary vs rolling vs recreate.
Implement canary release with rollback
Route a small percentage of traffic to the new version before full rollout:
deploy-canary:runs-on:ubuntu-latestenvironment:productionsteps:-uses:actions/checkout@v4-name:Deploycanary(10%traffic)run:./scripts/deploy-canary.sh${{env.IMAGE_TAG}}10-name:Monitorcanaryfor5minutesrun:|
for i in $(seq 1 10); do
sleep 30
ERROR_RATE=$(./scripts/get-error-rate.sh canary)
echo "Canary error rate: $ERROR_RATE%"
if (( $(echo "$ERROR_RATE > 1.0" | bc -l) )); then
echo "Error rate too high. Rolling back canary."
./scripts/rollback-canary.sh
exit 1
fi
done
-name:Promotecanaryto100%run:./scripts/promote-canary.sh${{env.IMAGE_TAG}}-name:Rollbackonanyfailureif:failure()run:./scripts/rollback-canary.sh
Cache dependencies and build artifacts
Cache node_modules by lockfile hash. Always restore-then-save so partial
installs don't get cached:
Cache keys should go from most-specific to least-specific in restore-keys.
A partial cache restore is almost always faster than a cold install.
Set up matrix builds
Test across multiple Node versions and operating systems in parallel:
test-matrix:runs-on:${{matrix.os}}strategy:fail-fast:false# don't cancel other jobs if one failsmatrix:node-version: [18, 20, 22]
os: [ubuntu-latest, windows-latest, macos-latest]
exclude:-os:windows-latestnode-version:18# don't test EOL Node on Windowssteps:-uses:actions/checkout@v4-uses:actions/setup-node@v4with:node-version:${{matrix.node-version}}cache:npm-run:npmci-run:npmtest
Set fail-fast: false when the matrix combinations are independent. Use
fail-fast: true (default) when any failure means the whole build is broken.
Error handling
Failure
Likely cause
Fix
npm ci fails with lockfile mismatch
package.json updated without re-running npm install
Run npm install locally and commit the updated package-lock.json
Cache miss on every run
Cache key includes volatile data (timestamps, random)
Use only stable inputs in cache key - lockfile hash, OS, Node version
Secrets not available in fork PR
GitHub does not expose secrets to workflows triggered by fork PRs
Use pull_request_target with caution, or require manual approval for external PRs
Workflow hangs with no output
Long-running process with no stdout, or missing --ci flag on test runner
Add timeout-minutes to the job; pass --ci flag to jest/vitest
Deploy fails but staging passed
Environment-specific secrets or config missing in production environment
Verify all vars and secrets are configured in the production environment settings
Matrix job passes on one OS but fails another
Path separators, line endings, or OS-specific tools diverge
Use path.join() in code; add .gitattributes for line endings; pin tool versions
Gotchas
Secrets not available in fork PRs - GitHub Actions does not expose repository secrets to workflows triggered by pull requests from forks (security boundary). Using pull_request_target to work around this requires careful vetting because it runs in the base repo context with full secret access - a malicious PR can exfiltrate them. Default to requiring manual approval for external PRs instead.
Required status check name must match exactly - If the workflow or job name changes (even a typo, case difference, or rename), GitHub branch protection silently stops enforcing the old required check. Always verify the status check name in branch protection settings after any workflow rename.
Cache poisoning via restore-keys - A restore-keys partial hit restores an older cache, then the job installs on top. If the old cache has a broken or security-patched package that npm ci doesn't replace (because it wasn't in the lockfile update), the cached bad state persists. Use npm ci (not npm install) so it always installs exactly what the lockfile specifies.
Immutable artifact drift - Building from source at deploy time (instead of promoting the artifact that passed staging) is a subtle but critical violation of the immutable artifact principle. A second build from the same SHA can produce different outputs if external dependencies (base images, npm packages without lockfiles) changed between builds.
Matrix fail-fast: true masking failures - With fail-fast: true (the default), a single failing job cancels all others, which can hide that multiple matrix combinations are broken. Use fail-fast: false when you want a full picture of which combinations fail, then switch back to true for normal CI.
References
For detailed implementation guidance on specific deployment strategies:
references/deployment-strategies.md - blue-green, canary, rolling, recreate,
A/B, and shadow deployments with ASCII diagrams and decision framework
Only load the references file when choosing or implementing a specific
deployment strategy - it is detailed and will consume context.
Companion check
On first activation of this skill in a conversation: check which companion skills are installed by running ls ~/.claude/skills/ ~/.agent/skills/ ~/.agents/skills/ .claude/skills/ .agent/skills/ .agents/skills/ 2>/dev/null. Compare the results against the recommended_skills field in this file's frontmatter. For any that are missing, mention them once and offer to install:
