Container Local Dev

Instructions

When to Use

• Use for Dockerfile + Compose for Next on Node LTS.
• Prefer monorepo-tooling for workspace package graphs first.
• Prefer env-config-agent for compose secret naming.

Add Docker and Compose for local and CI-like runs of Next.js (Node 20/22 LTS, pnpm).

1. .dockerignore: exclude .git, node_modules, .next, dist, .env* (use build args or runtime mount for secrets in dev only).
2. Multi-stage: deps (pnpm fetch/install) → builder (pnpm build) → runner (minimal: node_modules prod slice + .next/standalone if user enabled standalone output - match their next.config).
3. User: non-root USER node or numeric uid in final stage.
4. Compose: app + postgres + optional redis; healthchecks; named volumes; no secrets in compose YAML - .env local only gitignored.
5. Dev vs prod: docker compose -f compose.yaml -f compose.override.yaml pattern for hot reload optional - keep prod Dockerfile lean.
6. CI: same Dockerfile build in GitHub Actions to prove reproducibility - link github-actions-ci.

Outcomes

• File list + Dockerfile stage names + compose service graph (bullets).

Output Rules

suggest-shell: docker build / compose up commands; user runs them.

Scope and boundaries

• In scope: local dev containers, small prod-oriented images.
• Out of scope: Kubernetes manifests, service mesh, HIPAA hosting.

Safety

• Never print .env contents; use env_file: .env.local documentation only.

Troubleshooting

• ARM vs x86: buildx platforms for M-series Mac deploying to amd64 cloud.
• Huge context: fix .dockerignore before chasing layer cache.

Related skills

• monorepo-tooling - multi-package Docker contexts
• github-actions-ci - CI image build/cache
• env-config-agent - compose env files

GitHub: https://github.com/bh611627/skillcodex/tree/main/skills/container-local-dev/SKILL.md
npm: https://www.npmjs.com/package/@skillcodex/skills