# Dockerfile

> Generate an optimized Dockerfile — multi-stage build, security hardening, small image size.

- Skill: `khaitrang1995/dockerfile` (Agent Skill)
- Install (CLI): `npx skillmds@latest add khaitrang1995/dockerfile`
- Raw SKILL.md: https://api.skillmd.com/api/skills/khaitrang1995/dockerfile/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: DevOps & Infra
- Author: KhaiTrang1995 (https://skillmd.com/u/khaitrang1995)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/khaitrang1995/dockerfile

---


# /dockerfile — Generate a Dockerfile

## Input examples
```
/dockerfile .NET 10 Minimal API --prod
/dockerfile Angular 20 nginx --prod
/dockerfile Python FastAPI
/dockerfile Go service --prod
/dockerfile --dev fullstack .NET + Angular (docker-compose dev)
```

## Process
1. Detect the stack → pick the right base image
2. Multi-stage build: build stage → runtime stage
3. Security hardening
4. L1 approval → Write

## Mandatory rules
- **Multi-stage build** — separate build and runtime
- **Non-root user** — NEVER run the container as root
- **Specific tag** — `mcr.microsoft.com/dotnet/aspnet:10.0-alpine`, NEVER `latest`
- **COPY before RUN** — leverage layer caching (copy csproj/package.json first, restore, then copy source)
- **.dockerignore** — exclude bin/, obj/, node_modules/, .git/
- **HEALTHCHECK** — mandatory for production
- **NEVER hardcode** secrets/connection strings — use env vars
- **Alpine-based** whenever possible (small image size)

## Output
```
Dockerfile
.dockerignore
```

## References
- @.claude/rules/docker-conventions.md