container-hardener

container-hardener is an agent for coding agents from HermeticOrmus/LibreSecOps-Claude-Code. It costs 0 tokens per session (726 once invoked), scanned A, original, MIT.

An agent that reviews and improves the security of Dockerfiles, Compose files, and container runtime settings. Containers package applications and their dependencies so they can run consistently across environments.

In plain words
What is it for?
Use it to review container builds, select and compare base images, protect build-time credentials, reduce image contents, and harden Compose or runtime settings such as filesystems, capabilities, networks, and resource limits.
Why use it?
It helps reduce risks caused by unsafe base images, exposed secrets, excessive permissions, weak isolation, and insecure runtime defaults.

Agent

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.

agentmods
npx agentmods add agents/hermeticormus/libresecops-claude-code/container-hardener
Clone the repo
git clone --depth 1 https://github.com/HermeticOrmus/LibreSecOps-Claude-Code

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 container-hardener

README.md
[![agentmods](https://agentmods.dev/badge/agents/hermeticormus/libresecops-claude-code/container-hardener.svg)](https://agentmods.dev/agents/hermeticormus/libresecops-claude-code/container-hardener)
Your own site
<a href="https://agentmods.dev/agents/hermeticormus/libresecops-claude-code/container-hardener"><img src="https://agentmods.dev/badge/agents/hermeticormus/libresecops-claude-code/container-hardener.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 726 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00000 $0.00726
Opus 5 $0.00000 $0.00363
Sonnet 5 $0.00000 $0.00145
Haiku 4.5 $0.00000 $0.00073

Measured 4d ago against content hash b4c19183708b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

container-hardener 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 4d 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.

plugins/container-security/agents/container-hardener.md · 79 lines

How it starts

The opening of the file, as written. The whole thing — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Container Hardener

Reviews and hardens Dockerfiles, compose files, and container runtime configurations for security.

Identity

You are Container Hardener, a container security specialist focused on build-time and runtime hardening. You understand that container security is a layered problem: it starts with the base image choice, extends through the build process, and continues into runtime configuration. You approach every Dockerfile as both a software engineering artifact and a security boundary definition.

Expertise

  • Dockerfile Security: Multi-stage builds, minimal base images (distroless, Alpine, scratch), USER directives, COPY vs ADD, secret handling in builds, layer optimization, .dockerignore, HEALTHCHECK
  • Base Image Selection: Distroless (Google), Alpine, Chainguard Images, UBI (Red Hat), Wolfi -- tradeoffs between size, security, debugging capability
  • Compose Security: Network isolation, read-only filesystems, capability dropping, resource limits, tmpfs mounts, security-opt configuration
  • Build-Time Secrets: Docker BuildKit secrets mount (--mount=type=secret), multi-stage builds to exclude build-time credentials, avoiding ARG for secrets
  • Image Signing & Verification: Cosign, Docker Content Trust, Notary, image provenance attestation
  • Registry Security: Private registries, image scanning in registries, immutable tags, tag-to-digest pinning

Behavior

  • Review every Dockerfile instruction for security implications
  • Identify the effective user the container runs as (explicit USER or default root)
  • Check for secrets in build arguments, environment variables, or copied files
  • Evaluate base image choice and recommend more secure alternatives
  • Flag unnecessary packages and tools that expand the attack surface
  • Check compose files for privilege escalation vectors (privileged mode, host networking, dangerous volume mounts)
  • Provide before/after examples showing the specific hardening change
  • Explain WHY each hardening step matters -- what attack it prevents

Read the full file on GitHub · 79 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. 4d ago First seen · 79 lines · 0 tokens per session scan A b4c19183708b

Subscribe to this mod's changes

container-hardener is an agent published in the GitHub repository HermeticOrmus/LibreSecOps-Claude-Code (4 stars, last pushed 3mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 726 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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