claude-code-mastery-project-starter-kit: Command for Claude Code

Optimize Docker Build

Analyze and optimize the Docker setup for: $ARGUMENTS

If no Dockerfile path provided, search for Dockerfiles in the project root.

Step 0 — Auto-Branch (if on main)

Before modifying any files, check the current branch:

git branch --show-current

Default behavior (auto_branch = true in claude-mastery-project.conf):

• If on main or master: automatically create a feature branch and switch to it:

  git checkout -b chore/docker-optimize
  

  Report: "Created branch chore/docker-optimize — main stays untouched."
• If already on a feature branch: proceed
• If not a git repo: skip this check

To disable: Set auto_branch = false in claude-mastery-project.conf. When disabled, warn and ask the user before proceeding on main.

Step 1 — Find and Read All Docker Files

Read these files (if they exist):

• Dockerfile (or the path provided in $ARGUMENTS)
• docker-compose.yml / docker-compose.yaml
• .dockerignore
• package.json (for build scripts and dependencies)

Step 2 — Audit Against Best Practices

Check every rule below. For each violation, report:

• What's wrong
• Why it matters (performance impact or security risk)
• The fix

RULE 1: Multi-Stage Builds (MANDATORY)

Every production Dockerfile MUST use multi-stage builds. No exceptions.

# CORRECT — multi-stage: build artifacts don't ship to production
FROM node:20-alpine AS builder
WORKDIR /app
COPY package.json pnpm-lock.yaml ./
RUN corepack enable && pnpm install --frozen-lockfile
COPY . .
RUN pnpm build

FROM node:20-alpine AS runner
WORKDIR /app
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/node_modules ./node_modules
COPY --from=builder /app/package.json ./
CMD ["node", "dist/index.js"]

# WRONG — single stage ships devDependencies, source code, build tools
FROM node:20
WORKDIR /app
COPY . .
RUN npm install
RUN npm run build
CMD ["node", "dist/index.js"]

Why: Single-stage images are 3-10x larger. They ship TypeScript source, devDependencies, build tools — none of which are needed at runtime.