github-actions

name

github-actions

description

Generates and validates GitHub Actions workflows and custom actions (composite/Docker/JavaScript) with SHA-pinned supply chain security, SLSA attestation, OIDC federation, and harden-runner enforcement. Use when creating, editing, reviewing, or validating CI/CD pipelines, reusable workflows, monorepo CI patterns, container build/deploy orchestration, or advanced triggers (workflow_run, dispatch, ChatOps).

[GITHUB_ACTIONS]

Generate and validate production-ready GitHub Actions workflows and custom actions.

[TASKS]:

1. Gather requirements — triggers, runners, dependencies, environments, security posture.
2. Read best-practices.md.
3. Read version-discovery.md.
4. Read expressions-and-contexts.md.
5. (advanced triggers) Read advanced-triggers.md.
6. (custom actions) Read custom-actions.md.
7. Resolve action versions — git ls-remote, Context7 MCP, or WebSearch for latest SHA.
8. Generate — SHA-pinned actions, minimal permissions, concurrency, caching, timeouts, harden-runner.
9. Validate — gha check <files> gates actionlint, zizmor, and ratchet as one typed envelope; apply the best-practice checks.
10. Prove locally — gha run [-j JOB] [-e EVENT.json] runs Linux jobs in containers; gha pin freezes mutable refs; hosted CI rules merges.
11. Fix and re-validate until passing (max 3 iterations).

[SCOPE]:

• Workflow files (.github/workflows/*.yml).
• Custom actions — composite, Docker, JavaScript (.github/actions/*/action.yml).
• Reusable workflows (workflow_call).
• Supply chain — SLSA attestation, SBOM, Cosign signing.
• Monorepo CI — Nx affected detection, sparse checkout, pnpm workspace caching.

[01]-[ROUTING]

[REFERENCES]:

• [01]-BEST_PRACTICES: security hardening, supply chain, performance, anti-patterns
• [02]-VERSION_DISCOVERY: SHA resolution protocol, common actions index, permissions
• [03]-EXPRESSIONS: contexts, functions, injection prevention
• [04]-ADVANCED_TRIGGERS: workflow_run, dispatch, ChatOps, merge queue
• [05]-CUSTOM_ACTIONS: composite, Docker, JavaScript action authoring
• [06]-COMMON_ERRORS: syntax, expressions, deprecated commands
• [07]-SUPPLY_CHAIN: SHA pinning, OIDC, SBOM, harden-runner
• [08]-MODERN_FEATURES: reusable workflows, concurrency, matrix, node runtime
• [09]-RUNNERS: runner labels, deprecations
• [10]-ACT_USAGE: actionlint rules, act limitations

[TEMPLATES]:

• [01]-BASIC_WORKFLOW: lint, test, build, deploy CI pipeline with parameterized runtime
• [02]-REUSABLE_WORKFLOW: workflow_call with typed inputs, secrets, version extraction
• [03]-COMPOSITE_ACTION: multi-step action with parameterized runtime and error handling
• [04]-DOCKER_ACTION: container action with distroless multi-stage Dockerfile pattern
• [05]-JAVASCRIPT_ACTION: Node 24 action with pre/post lifecycle, typed error handling

[EXAMPLES]:

• [01]-NODEJS_CI: matrix testing, caching, artifact upload, coverage, summaries
• [02]-DOCKER_BUILD_PUSH: multi-platform builds, GHCR, BuildKit caching, SLSA provenance
• [03]-MONOREPO_CI: Nx affected detection, pnpm workspace, sparse checkout
• [04]-DEPENDENCY_REVIEW: multi-job security with dep review, CodeQL, Gitleaks, triage
• [05]-SBOM_ATTESTATION: SBOM, Trivy severity gating, Cosign, gh attestation verify
• [06]-SETUP_NODE_CACHED: smart caching, corepack detection, cache-dir resolution
• [07]-CHATOPS_DISPATCH: slash commands, injection guard, App token, env indirection
• [08]-OIDC_CLOUD_AUTH: AWS/GCP/Azure OIDC, output normalization
• [09]-RELEASE_DEPLOY: environment promotion, reusable workflow, concurrency groups
• [10]-DOCKER_LINT_SCAN: Trivy scan, hadolint, SARIF output
• [11]-PR_CHANGE_ROUTER: paths-filter, dynamic matrix, label sync

[02]-[STANDARDS]

Every generated workflow enforces defense-in-depth: supply chain integrity prevents compromised actions from executing, minimal permissions limit blast radius if a job is compromised, and harden-runner detects anomalous behavior at runtime. These layers are independent — failure of one leaves others intact.

[CRITICAL]:

• [ALWAYS]: SHA-pin every uses: reference — CVE-2025-30066 retargeted tj-actions mutable tags (@v1, @main) to compromise consuming repos.
• [ALWAYS]: step-security/harden-runner as first step in every job — detected the tj-actions breach.
• [ALWAYS]: Top-level permissions: {} (deny-all default); grant minimal per-job permissions.
• [ALWAYS]: timeout-minutes: on every job — prevents runaway billing on stuck workflows.

[IMPORTANT]:

• [ALWAYS]: OIDC federation (id-token: write) for cloud auth — eliminates static credentials entirely.
• [ALWAYS]: actions/create-github-app-token for cross-repo ops — scoped, 1-hour expiry, survives offboarding.
• [ALWAYS]: >> $GITHUB_OUTPUT for step outputs; >> $GITHUB_STEP_SUMMARY for job summaries.
• [NEVER]: Direct ${{ }} interpolation of untrusted input in run: blocks — route through env: indirection.

[REFERENCE] best-practices.md — Security checklist, supply chain controls, anti-patterns.

[03]-[TEMPLATES]

Templates use [PLACEHOLDER] syntax for generation-time substitution. SHA resolution happens at generation time via the discovery protocol — templates contain placeholder SHAs, not static pins.

[03.1]-[PLACEHOLDER_CONVENTION]

All templates use a unified [UPPER_SNAKE_CASE] placeholder convention:

[INDEX]	[CATEGORY]	[PLACEHOLDERS]
[01]	Identity	[ACTION_NAME], [WORKFLOW_NAME], [DESCRIPTION], [AUTHOR_NAME]
[02]	Runtime	[RUNTIME_VERSION], [RUNTIME_ENV_KEY], [ENABLE_CMD]
[03]	Package Mgr	[PACKAGE_MANAGER], [INSTALL_CMD]
[04]	Build/Test	[BUILD_CMD], [LINT_CMD], [TEST_CMD], [BUILD_PATH], [RESULTS_PATH]
[05]	Deploy	[ENV_NAME], [ENV_URL], [DEPLOY_CMD], [VERIFY_CMD]
[06]	Secrets	[SECRET_KEY], [SECRET_NAME], [REGISTRY_TOKEN]
[07]	Docker	[BASE_IMAGE], [BUILDER_IMAGE], [ENTRYPOINT]

[03.2]-[HARDEN_RUNNER_SCOPE]

harden-runner is included as the first step in every workflow job template (basic, reusable). Action templates (composite, Docker, JavaScript) do NOT include harden-runner — the calling workflow is responsible for adding it as the first step in the job that invokes the action. Actions are steps, not jobs.

[REFERENCE] custom-actions.md — Action type selection, metadata, runtime deprecation.

[04]-[EXAMPLES]

Load the relevant examples before generation to match the target scenario.

[05]-[ACTION_DISCOVERY]

Static SHA catalogs decay — actions release frequently and stale pins miss security patches. Resolve versions at generation time. Never embed hardcoded SHAs in reference docs or templates.

[RESOLUTION_PROTOCOL]:

1. git ls-remote --tags https://github.com/{owner}/{repo} — verify tag exists.
2. gh api repos/{owner}/{repo}/git/ref/tags/{tag} --jq '.object.sha' — resolve tag to full SHA.
3. Format: owner/repo@<40-char-SHA> # vX.Y.Z.

[FALLBACK_METHODS]:

• Context7 MCP: resolve-library-id then query-docs for action documentation.
• WebSearch: "[owner/repo] [version] github action" for release notes.

[IMPORTANT]:

• [ALWAYS]: Verify the tag exists before pinning — deleted tags return empty results.
• [ALWAYS]: Include version comment suffix (# vX.Y.Z) — Dependabot parses it for automated updates.
• [NEVER]: Embed static SHAs in reference files — they decay within weeks.

[REFERENCE] version-discovery.md — Discovery protocol, SHA pinning format, common actions index, automated maintenance.

[06]-[VALIDATION]

[VALIDATION_PIPELINE]: gha check folds the first three stages into one typed envelope.

[INDEX]	[STAGE]	[TOOL]	[VALIDATES]
[01]	Static Analysis	actionlint	YAML syntax, expressions, runner labels, action inputs, CRON, globs.
[02]	Security Audit	zizmor	Injection, credential persistence, unpinned uses, permission excess.
[03]	Ref Pinning	ratchet	Mutable uses: references; gha pin rewrites them to SHAs.
[04]	Best Practices	custom checks	SHA pinning, permissions, injection, timeouts, harden-runner.
[05]	Local Execution	act	gha run executes jobs in containers; dry-run via gha run --dryrun.

[BEST_PRACTICE_CHECKS]:

[INDEX]	[CHECK]	[TAG]	[DETECTS]
[01]	Deprecated commands	[DEPRECATED-CMD]	::set-output, ::save-state, ::set-env, ::add-path.
[02]	Missing permissions	[PERMISSIONS]	No top-level permissions: {} deny-all default.
[03]	Unpinned actions	[UNPINNED]	Mutable tags (@v1, @main), abbreviated SHAs.
[04]	SHA without comment	[SHA-NO-COMMENT]	SHA-pinned but missing # vX.Y.Z version comment.
[05]	Missing timeout	[TIMEOUT]	Jobs without timeout-minutes: (default is 6 hours).
[06]	Deprecated runners	[RUNNER]	ubuntu-20.04, macos-12, macos-13, windows-2019.
[07]	Missing concurrency	[CONCURRENCY]	No concurrency: group or missing cancel-in-progress.
[08]	PAT usage	[APP-TOKEN]	PATs for cross-repo ops (use create-github-app-token).
[09]	No harden-runner

[ERROR_ROUTING]: Match error patterns to reference files — common_errors.md (syntax, expressions, deprecated), runners.md (labels, deprecations), supply_chain.md (SHA, OIDC, SBOM, harden-runner), modern_features.md (reusable workflows, concurrency, matrix, node runtime), act_usage.md (actionlint rules, act limitations).

[TROUBLESHOOTING]:

[INDEX]	[ISSUE]	[SOLUTION]
[01]	Tools not found	gha runtimeInputs unresolved — forge-redeploy --switch.
[02]	Docker not running	Start the runtime; gha check needs no Docker.
[03]	act fails, GitHub works	See act_usage.md — Limitations.
[04]	ARM Mac arch mismatch	Add --container-architecture linux/amd64.
[05]	Custom runner labels	Declare in .github/actionlint.yaml.

[REFERENCE] best-practices.md — Anti-patterns with specific remediations.