multi-stage-dockerfile

multi-stage-dockerfile is a skill for Claude Code, Codex from fabioc-aloha/Alex_Skill_Mall. It costs 17 tokens per session (452 once invoked), scanned A, a copy of multi-stage-dockerfile, MIT.

A guide to writing multi-stage Dockerfiles, which build an application in one container stage and run it in a smaller separate stage.

In plain words
What is it for?
Use it to containerize applications in different languages or frameworks, organize build and test stages, and create leaner runtime images.
Why use it?
It helps produce smaller runtime images with fewer unnecessary dependencies while keeping builds reproducible and making better use of Docker's layer cache.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to containerize applications in different languages or frameworks, organize build and test stages, and create leaner runtime images.

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Install with agentmods
npx agentmods add skills/fabioc-aloha/alex_skill_mall/multi-stage-dockerfile
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add fabioc-aloha/Alex_Skill_Mall --skill multi-stage-dockerfile
Clone the repo
git clone --depth 1 https://github.com/fabioc-aloha/Alex_Skill_Mall

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

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README.md
[![agentmods](https://agentmods.dev/badge/skills/fabioc-aloha/alex_skill_mall/multi-stage-dockerfile/github.svg)](https://agentmods.dev/skills/fabioc-aloha/alex_skill_mall/multi-stage-dockerfile)
Your own site
<a href="https://agentmods.dev/skills/fabioc-aloha/alex_skill_mall/multi-stage-dockerfile"><img src="https://agentmods.dev/badge/skills/fabioc-aloha/alex_skill_mall/multi-stage-dockerfile/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for multi-stage-dockerfile

Your own site · 80×15
<a href="https://agentmods.dev/skills/fabioc-aloha/alex_skill_mall/multi-stage-dockerfile"><img src="https://agentmods.dev/badge/skills/fabioc-aloha/alex_skill_mall/multi-stage-dockerfile.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 17 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 452 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 97% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00017 $0.00452
Opus 5 $0.00009 $0.00226
Sonnet 5 $0.00003 $0.00090
Haiku 4.5 $0.00002 $0.00045

Measured 6d ago against content hash 56c9532717b0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

multi-stage-dockerfile scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

97% identical to multi-stage-dockerfile — 3 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

plugins/cloud-infrastructure/multi-stage-dockerfile/skills/multi-stage-dockerfile/SKILL.md · 48 lines

How it starts

The opening of the file, as written. The whole thing — 48 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Your goal is to help me create efficient multi-stage Dockerfiles that follow best practices, resulting in smaller, more secure container images.

Multi-Stage Structure

  • Use a builder stage for compilation, dependency installation, and other build-time operations
  • Use a separate runtime stage that only includes what's needed to run the application
  • Copy only the necessary artifacts from the builder stage to the runtime stage
  • Use meaningful stage names with the AS keyword (e.g., FROM node:18 AS builder)
  • Place stages in logical order: dependencies → build → test → runtime

Base Images

  • Start with official, minimal base images when possible
  • Specify exact version tags to ensure reproducible builds (e.g., python:3.11-slim not just python)
  • Consider distroless images for runtime stages where appropriate
  • Use Alpine-based images for smaller footprints when compatible with your application
  • Ensure the runtime image has the minimal necessary dependencies

Layer Optimization

  • Organize commands to maximize layer caching
  • Place commands that change frequently (like code changes) after commands that change less frequently (like dependency installation)
  • Use .dockerignore to prevent unnecessary files from being included in the build context
  • Combine related RUN commands with && to reduce layer count
  • Consider using COPY --chown to set permissions in one step

Security Practices

  • Avoid running containers as root - use USER instruction to specify a non-root user
  • Remove build tools and unnecessary packages from the final image
  • Scan the final image for vulnerabilities
  • Set restrictive file permissions
  • Use multi-stage builds to avoid including build secrets in the final image

Performance Considerations

  • Use build arguments for configuration that might change between environments
  • Leverage build cache efficiently by ordering layers from least to most frequently changing
  • Consider parallelization in build steps when possible
  • Set appropriate environment variables like NODE_ENV=production to optimize runtime behavior
  • Use appropriate healthchecks for the application type with the HEALTHCHECK instruction

Read the full file on GitHub · 48 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 48 lines · 17 tokens per session scan A 56c9532717b0

Subscribe to this mod's changes

multi-stage-dockerfile is a skill published in the GitHub repository fabioc-aloha/Alex_Skill_Mall (4 stars, last pushed 2d ago), licensed MIT. It adds 17 tokens to every session and 452 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 97% identical to multi-stage-dockerfile, differing in 3 lines, and is treated as a copy.

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