Docker Architect

Docker Architect

Overview

Produce production-grade, secure, right-sized Docker images and Compose environments end-to-end: inventory → design → implement → test → CI. Prefer minimal, reproducible builds (multi-stage + BuildKit) and least-privilege runtime defaults.

Quick Start (always do this first)

Resolve skill_dir as the directory containing this skill before running bundled scripts.

1. Inventory the repo and existing container config:
   • Run python3 "$skill_dir/scripts/docker_inventory.py" --root .
2. Choose the target:
   • New containerization → follow “New build workflow”
   • Existing Dockerfiles/Compose → follow “Audit + refactor workflow”
3. Validate locally:
   • docker buildx version
   • docker buildx build ... (or docker build ...)
   • docker compose config and docker compose up --build

Template rendering example (edit variables per repo):

• python3 "$skill_dir/scripts/render_template.py" --template .dockerignore --out .dockerignore
• python3 "$skill_dir/scripts/render_template.py" --template compose/docker-compose.yml --out docker-compose.yml --var IMAGE_NAME=myapp:dev --var HOST_PORT=8000 --var CONTAINER_PORT=8000
• python3 "$skill_dir/scripts/render_template.py" --template compose/docker-compose.dev.yml --out docker-compose.dev.yml --var CONTAINER_PORT=8000 --var DEV_COMMAND='[\"python\",\"-m\",\"uvicorn\",\"myapp.api:app\",\"--host\",\"0.0.0.0\",\"--port\",\"8000\",\"--reload\"]'

Workflow Decision Tree

1. Scope:
   • Dev-only (fast iteration, source mounts, hot reload) → prefer docker-compose.dev.yml
   • Prod-like (immutable images, healthchecks, least privilege) → prefer docker-compose.yml + docker-compose.prod.yml
2. Artifact type:
   • Single service → one Dockerfile + optional compose for deps
   • Multi-service → compose with explicit networks/volumes and healthchecks
3. Publish target:
   • Local only → keep simple; optional CI smoke checks
   • Registry publish → add CI build/test/scan/push + provenance/SBOM (if available)

New build workflow (Dockerfile + .dockerignore + compose)

1. Pick a base strategy (see references/dockerfile_patterns.md):
   • Multi-stage build; runtime image is minimal; build tools stay in builder stage.
   • Prefer slim/distroless where feasible; default to non-root user.
2. Add .dockerignore early (template in assets/templates/.dockerignore).
3. Create a Dockerfile from templates:
   • Prefer assets/templates/python/Dockerfile.uv for modern Python/uv
   • Prefer assets/templates/node/Dockerfile.pnpm for Node + pnpm
   • Use python3 "$skill_dir/scripts/render_template.py" ... to render with variables.
4. Add a compose file for dependencies (DB/cache) and dev/prod profiles:
   • Start from assets/templates/compose/docker-compose.yml + an override (assets/templates/compose/docker-compose.dev.yml or assets/templates/compose/docker-compose.prod.yml)
   • Optional deps file: assets/templates/compose/docker-compose.deps.yml
5. Local validation:
   • bash "$skill_dir/scripts/smoke_test_container.sh" --help
   • Optional: --build-check (Docker build checks) and --pull (fresh base images)
   • For compose: bash "$skill_dir/scripts/smoke_test_compose.sh" --help

Audit + refactor workflow (existing Dockerfiles/Compose)

1. Inventory + static audit:
   • python3 "$skill_dir/scripts/docker_audit.py" --root .
2. Identify high-risk issues (see references/security_hardening.md):
   • Secrets in image/build args, root/privileged runtime, overly broad mounts, host networking, “latest” tags, missing healthchecks.
3. Refactor incrementally:
   • Keep behavior stable, then tighten (non-root, read-only fs, drop caps, pin images, shrink layers).
4. Validate end-to-end:
   • docker buildx build ...
   • docker compose up --build and run the app’s normal test/health commands.
5. Produce a concise report (template in references/review_template.md).

CI integration workflow (GitHub Actions default)

1. Start from assets/templates/ci/github-actions-docker-ci.yml.
   • For publish + SBOM/provenance to GHCR: assets/templates/ci/github-actions-docker-publish.yml
2. Ensure CI runs:
   • docker buildx build (cache enabled)
   • docker compose config (compose validation)
   • optional: build checks (docker build --check) and scan/SBOM/provenance steps
3. Prefer pinned action versions and least-privilege permissions (see references/ci_github_actions.md).

“Latest/correct” research rule (do not guess)

When “latest” matters (base images, distro versions, language runtimes, CVEs):

1. Use Exa to confirm current official guidance and tags (official sources preferred).
2. Use docker buildx imagetools inspect <image:tag> to confirm manifests/platforms.
3. If unsure, mark as UNVERIFIED and propose a safe default with a verification step.

Tooling leverage (when it helps)

• Exa: find current best practices, base image changes, CVE guidance, GitHub Actions deprecations.
• Context7: confirm framework-specific build outputs (e.g., Next.js, FastAPI, uvicorn/gunicorn, etc.).
• Zen: use zen.secaudit for a structured container/security audit and zen.analyze for architecture-sensitive compose design.
• gh_grep: search public repos for battle-tested patterns (entrypoints, healthchecks, buildx/bake, compose profiles).
• opensrc: inspect dependency internals when container behavior depends on packaging details.

Bundled resources

Scripts

• scripts/docker_inventory.py: detect stack + existing Docker/Compose files.
• scripts/docker_audit.py: heuristic linting of Dockerfiles/Compose for security/correctness.
• scripts/render_template.py: render templates with {{VARS}} into repo files.
• scripts/smoke_test_container.sh: build/run basic health check locally.
• scripts/smoke_test_compose.sh: validate + bring up compose and check health.

References (load as needed)

• references/dockerfile_patterns.md: BuildKit, caching, multi-stage, runtime hardening.
• references/compose_patterns.md: compose patterns, profiles, healthchecks, secrets/configs.
• references/security_hardening.md: least privilege, capabilities, read-only fs, supply chain.
• references/ci_github_actions.md: CI build/test/scan/publish patterns.
• references/review_template.md: audit report format and deliverables checklist.

Assets (templates)

Templates live under assets/templates/ (Dockerfile variants, compose variants, CI workflow, .dockerignore, docker-bake.hcl).