dockerfile-guardian

name	dockerfile-guardian
description	Verifies new files/directories are properly included in Dockerfile COPY instructions and not excluded by .dockerignore. Invoke when adding new files to project root.

Dockerfile Guardian

This skill ensures new files and directories added to the project root are properly configured for Docker builds.

When to Invoke

• New files are added to project root
• New directories are created in project root
• User mentions creating new configuration files
• User adds new source files to root level
• Before committing new root-level files

What It Checks

1. Dockerfile COPY Instructions

• Are new files covered by existing COPY patterns?
• Do they need explicit COPY instructions?
• Are paths correctly specified?

2. .dockerignore Configuration

• Are new files accidentally excluded?
• Should they be included in the build context?
• Are patterns too broad or too narrow?

Check Process

Step 1: Identify New Files

# List recently added files
git status --short

# Check for untracked files in root
ls -la | grep -v "^\."

Step 2: Check Dockerfile

# View COPY instructions
grep -n "COPY" Dockerfile

Step 3: Check .dockerignore

# View ignore patterns
cat .dockerignore

Step 4: Verify Coverage

For each new file/directory:

• Is it needed in the Docker image?
• Is it covered by a COPY pattern?
• Is it excluded by .dockerignore?
• Does it need special handling?

Common Patterns

Files That Need COPY

• Configuration files (*.json, *.yaml, *.env.example)
• Source code directories (src/, lib/, components/)
• Build files (package.json, tsconfig.json, Dockerfile)
• Asset directories (public/, assets/, static/)

Files That Should Be Ignored

• Node modules (node_modules/)
• Build outputs (dist/, build/)
• Git files (.git/, .gitignore)
• IDE files (.idea/, .vscode/)
• Environment files (.env, .env.local)
• Cache directories (.cache/, pycache/)

Output Format

## Dockerfile Check Report

### New Files Detected
- [filename] - [status: ✅ covered / ⚠️ needs attention / ❌ excluded]

### Recommendations
1. [Recommendation 1]
2. [Recommendation 2]

### Required Changes (if any)
[Dockerfile or .dockerignore modifications needed]

Quick Fix Commands

# Add to Dockerfile (example)
echo "COPY new-file.json /app/" >> Dockerfile

# Remove from .dockerignore (example)
sed -i '/new-directory/d' .dockerignore