container-security

container-security is a skill for Claude Code from julianobarbosa/claude-code-skills. It costs 108 tokens per session (2,641 once invoked), scanned C, original, MIT.

A guide for checking container images for security problems and making Dockerfiles safer. Containers package an application and its dependencies so they can run consistently across environments.

In plain words
What is it for?
Use it to scan images with Trivy, review CVEs, harden Dockerfiles, rebuild images, and import base images into Azure Container Registry.
Why use it?
It helps find known vulnerabilities, avoid unsafe image settings, and work around Docker Hub download limits when building images in Azure.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Good fit Use it to scan images with Trivy, review CVEs, harden Dockerfiles, rebuild images, and import base images into Azure Container Registry.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/julianobarbosa/claude-code-skills/container-security
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 julianobarbosa/claude-code-skills --skill container-security
Clone the repo
git clone --depth 1 https://github.com/julianobarbosa/claude-code-skills

Made for: 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-security

README.md
[![agentmods](https://agentmods.dev/badge/skills/julianobarbosa/claude-code-skills/container-security.svg)](https://agentmods.dev/skills/julianobarbosa/claude-code-skills/container-security)
Your own site
<a href="https://agentmods.dev/skills/julianobarbosa/claude-code-skills/container-security"><img src="https://agentmods.dev/badge/skills/julianobarbosa/claude-code-skills/container-security.svg" alt="Measured on agentmods" height="20"></a>
Per session 108 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,641 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 4 findings. 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 $0.00108 $0.02641
Opus 5 $0.00054 $0.01321
Sonnet 5 $0.00022 $0.00528
Haiku 4.5 $0.00011 $0.00264

Measured 7d ago against content hash 2185f0006801, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade C, and why

container-security scanned grade C with 4 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 7d 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.

Asks for rootlowPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

chmod 700 /home/<user>/.ssh && \

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Downloads and executes remote codemediumSupply chain

curl | sh runs whatever the server returns today, which is not necessarily what it returned when this was reviewed.

RUN curl .../releases/latest/download/tool | bash

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Recursive force deletemediumDestructive command

rm -rf with a variable or a broad path is one typo away from removing the wrong tree.

- **Clean apt caches**: always end with `&& rm -rf /var/lib/apt/lists/*`

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Makes network callslowCapability

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

RUN curl .../releases/latest/download/tool | bash
skills/container-security/SKILL.md · 241 lines

How it starts

The opening of the file, as written. The whole thing — 241 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Container Image Security

Complete workflow for securing container images: scan, analyze, harden, verify.

Workflow Overview

Import base image to ACR → Build → Scan with Trivy → Analyze CVEs → Harden Dockerfile → Rebuild → Re-scan → Verify

1. Import Base Images to ACR

Avoid Docker Hub rate limits by importing base images into your private ACR. Azure's infrastructure pulls on your behalf — no Docker Hub auth needed.

# Import a public image into ACR
az acr import --name <registry> \
  --source docker.io/<image>:<tag> \
  --image <local-path>/<image>:<tag>

# Example: import code-server
az acr import --name example-app \
  --source docker.io/codercom/code-server:4.107.1 \
  --image addons/code-server:4.107.1

# Verify
az acr repository show --name <registry> --repository <local-path>/<image>

Then update the Dockerfile FROM to reference the ACR copy:

# Before (hits Docker Hub rate limits in ACR cloud builds)
FROM codercom/code-server:latest

# After (pulls from local ACR — no rate limit)
FROM example-app.azurecr.io/addons/code-server:4.107.1

Important: ACR cloud builds (az acr build) are unauthenticated against Docker Hub. Any FROM referencing Docker Hub will eventually hit rate limits. Always import first.

2. Build with ACR

az acr build --registry <registry> --image <repo>:<tag> -f Dockerfile .

ACR builder limitations — these Docker features are NOT supported:

  • COPY <<'EOF' heredoc syntax (BuildKit-only) — use RUN printf or RUN cat instead
  • Multi-platform builds require --platform flag
  • BuildKit-specific RUN --mount directives

3. Scan with Trivy

Option A: Trivy via ACR Task (recommended for CI)

First, import Trivy itself into ACR (once):

az acr import --name <registry> \
  --source docker.io/aquasec/trivy:latest \
  --image tools/trivy:latest

Then scan:

# Table format for human review
az acr run --registry <registry> \
  --cmd "<registry>.azurecr.io/tools/trivy:latest image \
    --severity HIGH,CRITICAL \
    <registry>.azurecr.io/<image>:<tag>" /dev/null

# JSON format for programmatic analysis
az acr run --registry <registry> \
  --cmd "<registry>.azurecr.io/tools/trivy:latest image \
    --severity HIGH,CRITICAL --format json \
    <registry>.azurecr.io/<image>:<tag>" /dev/null

Read the full file on GitHub · 241 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 7d ago First seen · 241 lines · 108 tokens per session scan C 2185f0006801

Subscribe to this mod's changes

container-security is a skill published in the GitHub repository julianobarbosa/claude-code-skills (10 stars, last pushed 12d ago), licensed MIT. It adds 108 tokens to every session and 2,641 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it C with 4 findings (asks for root, downloads and executes remote code, recursive force delete). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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