docker-hardening

docker-hardening is a skill for Claude Code from jakesterns/agent-skills. It costs 26 tokens per session (309 once invoked), scanned A, original, MIT.

A review guide for Dockerfiles and container settings. Docker packages an application with its dependencies so it can run consistently across machines.

In plain words
What is it for?
Reviewing Dockerfiles, Compose files, build logs, image details, runtime settings, and deployment readiness, then producing fixes, checklists, and validation commands.
Why use it?
It helps find security weaknesses, unreproducible builds, oversized images, and deployment problems before they cause incidents.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the docker-hardening plugin — 1 skill shipped together

Good fit Reviewing Dockerfiles, Compose files, build logs, image details, runtime settings, and deployment readiness, then producing fixes, checklists, and validation commands.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/jakesterns/agent-skills/docker-hardening
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 jakesterns/agent-skills --skill docker-hardening
Clone the repo
git clone --depth 1 https://github.com/jakesterns/agent-skills

Made for: Claude Code.

Or install docker-hardening, the plugin that ships this one along with the rest of its 1 skill.

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.

agentmods badge for docker-hardening

README.md
[![agentmods](https://agentmods.dev/badge/skills/jakesterns/agent-skills/docker-hardening/github.svg)](https://agentmods.dev/skills/jakesterns/agent-skills/docker-hardening)
Your own site
<a href="https://agentmods.dev/skills/jakesterns/agent-skills/docker-hardening"><img src="https://agentmods.dev/badge/skills/jakesterns/agent-skills/docker-hardening/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 docker-hardening

Your own site · 80×15
<a href="https://agentmods.dev/skills/jakesterns/agent-skills/docker-hardening"><img src="https://agentmods.dev/badge/skills/jakesterns/agent-skills/docker-hardening.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 26 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 309 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found 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 $0.00026 $0.00309
Opus 5 $0.00013 $0.00154
Sonnet 5 $0.00005 $0.00062
Haiku 4.5 $0.00003 $0.00031

Measured 9d ago against content hash 5df68cfbe4f0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

docker-hardening scanned grade A with 1 finding 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 9d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

5. Check supply-chain risk: curl-pipe-shell, unsigned downloads, mutable tags, and unverified artifacts.
plugins/docker-hardening/skills/docker-hardening/SKILL.md · 38 lines

What it actually says

Docker Hardening

Use this skill when reviewing or improving Dockerfiles, Compose files, container runtime flags, or image build workflows.

Inputs

  • Dockerfile, compose file, build logs, image metadata, deployment environment, and application runtime requirements

Steps

  1. Review base image choice, version pinning, architecture, and maintenance status.
  2. Check build reproducibility: pinned dependencies, deterministic package install, cache hygiene, and lockfile use.
  3. Reduce image size where it also improves reliability or security: multi-stage builds, minimal runtime dependencies, and cleaned package caches.
  4. Review runtime security: non-root user, file permissions, capabilities, read-only filesystem, secrets handling, exposed ports, and health checks.
  5. Check supply-chain risk: curl-pipe-shell, unsigned downloads, mutable tags, and unverified artifacts.
  6. Validate operational readiness: signals, graceful shutdown, logging, startup command, environment variables, and resource expectations.

Output

Return:

  • Container risk summary
  • Recommended Dockerfile/config changes
  • Security hardening checklist
  • Reproducibility and size notes
  • Validation commands such as build, run, scan, or smoke test

Guidelines

  • Do not optimize image size at the expense of clarity or correctness.
  • Prefer pinned, maintained base images.
  • Keep production runtime separate from build tooling when practical.
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. 9d ago First seen · 38 lines · 26 tokens per session scan A 5df68cfbe4f0

Subscribe to this mod's changes

docker-hardening is a skill published in the GitHub repository jakesterns/agent-skills (2 stars, last pushed 3mo ago), licensed MIT. It adds 26 tokens to every session and 309 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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