Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/LerianStudio/ringnpx agentmods add skills/lerianstudio/ring/hardening-dockerfilesWrote 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.
[](https://agentmods.dev/skills/lerianstudio/ring/hardening-dockerfiles)<a href="https://agentmods.dev/skills/lerianstudio/ring/hardening-dockerfiles"><img src="https://agentmods.dev/badge/skills/lerianstudio/ring/hardening-dockerfiles/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.
<a href="https://agentmods.dev/skills/lerianstudio/ring/hardening-dockerfiles"><img src="https://agentmods.dev/badge/skills/lerianstudio/ring/hardening-dockerfiles.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00106 | $0.01297 |
| Opus 5.5 | $0.00042 | $0.00519 |
| Sonnet 5.5 | $0.00021 | $0.00259 |
| Haiku 4.5 | $0.00011 | $0.00130 |
Grade A, and why
ring:hardening-dockerfiles 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 175 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Docker Security (Health Score Grade A)
When to use
- Creating a new Dockerfile
- Auditing an existing Dockerfile for security
- Preparing images for Docker Hub publication
- Docker Hub health score is below grade A
Skip when
- Project has no Dockerfile and none is being created
- Changes are application-code only with no Docker modifications
- Using pre-built images without custom Dockerfile
Related
Complementary: ring:implementing-tasks, ring:creating-helm-charts
General Dockerfile patterns: dev-team/docs/standards/devops.md#containers.
This skill focuses on Docker Hub Health Score compliance.
Health Score Policies
| # | Policy | Weight | Compliance |
|---|---|---|---|
| 1 | Default non-root user | Required | USER directive with non-root user |
| 2 | No fixable critical/high CVEs | Required | Distroless or Alpine, multi-stage |
| 3 | No high-profile vulnerabilities (CISA KEV) | Required | Up-to-date base images |
| 4 | No AGPL v3 licenses | Required | Audit dependencies |
| 5 | Supply chain attestations (SBOM + provenance) | Required | Pipeline config |
| 6 | No outdated base images | Optional | Only for Docker Hub hosted images |
| 7 | No unapproved base images | Optional | Only for Docker Hub hosted images |
Policies 6-7 are not evaluated when using non-Docker Hub base images (gcr.io/distroless, etc.).
Policy Implementation
Policy 1 — Non-Root User
# Alpine
RUN addgroup -S appgroup && adduser -S appuser -G appgroup
USER appuser
# Debian/Ubuntu
RUN groupadd -r appgroup && useradd -r -g appgroup appuser
USER appuser
# Distroless (pre-existing user)
USER nonroot:nonroot
USER root does NOT satisfy this policy.
Policies 2 & 3 — Minimal Attack Surface
# Go (statically compiled) — ~0 CVEs
FROM gcr.io/distroless/static-debian12
# Go (CGO) or general
FROM gcr.io/distroless/base-debian12
# Node.js
FROM node:22-alpine
# Multi-stage mandatory
FROM golang:1.23-alpine AS builder
# ... build ...
FROM gcr.io/distroless/static-debian12
COPY --from=builder /app/binary /app/binary
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.
- 1mo ago First seen · 175 lines · 106 tokens per session scan A a489c09e32c9
ring:hardening-dockerfiles is a skill published in the GitHub repository LerianStudio/ring (218 stars, last pushed 4d ago), licensed Apache-2.0. It adds 106 tokens to every session and 1,297 once invoked, about $0.0004 per session on Opus 5.5. 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 2026-09-03.
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