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.
npx agentmods add skills/fellipeutaka/leon/dockernpx skills add fellipeutaka/leon --skill dockergit clone --depth 1 https://github.com/fellipeutaka/leonWhat 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 | $0.00049 | $0.03806 |
| Opus 5 | $0.00024 | $0.01903 |
| Sonnet 5 | $0.00010 | $0.00761 |
| Haiku 4.5 | $0.00005 | $0.00381 |
Grade B, and why
docker scanned grade B with 3 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 2d 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.
| Run as root | `USER 1001` or named user | 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.
RUN mkdir src && echo "fn main() {}" > src/main.rs && cargo build --release && rm -rf src 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.
CMD wget -qO- http://localhost:3000/health || exit 1 How it starts
The opening of the file, as written. The whole thing — 601 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Docker Expert
When to Use
- Creating or reviewing Dockerfiles
- Optimizing image size or build performance
- Hardening container security
- Setting up Docker Compose for multi-service apps
- Debugging container networking, volumes, or runtime issues
- Containerizing applications (Node.js, Python, Go, Java, Rust)
Out of scope (recommend dedicated skills):
- Kubernetes orchestration → kubernetes expert
- CI/CD pipelines → github-actions expert
- Cloud-specific container services (ECS, Cloud Run) → devops expert
Core Principles
- Layer caching — order layers from least to most frequently changing
- Security-first — non-root users, minimal attack surface, no secrets in layers
- Minimal images — only include what's needed at runtime
- Reproducibility — pin versions, avoid
latesttag, use lockfiles
Base Image Selection
Recommended hierarchy (most to least preferred):
| Base Image | Size | Shell | Use Case |
|---|---|---|---|
cgr.dev/chainguard/* (Wolfi) |
~10-30MB | Yes | Zero-CVE goal, SBOM included |
alpine:3.21 |
~7MB | Yes | General-purpose minimal |
gcr.io/distroless/* |
~2-5MB | No | Hardened production, no debug |
*-slim variants |
~70-100MB | Yes | When Alpine compatibility is an issue |
scratch |
0MB | No | Static binaries (Go, Rust) |
Rules:
- Always pin exact versions:
node:22.14.0-alpine3.21notnode:alpine - Never use
latest— breaks reproducibility - Match base to actual runtime needs
Dockerfile Best Practices
Layer Ordering
# 1. Base image + system deps (rarely change)
FROM node:22-alpine
RUN apk add --no-cache dumb-init
# 2. Dependencies (change occasionally)
WORKDIR /app
COPY package.json package-lock.json ./
RUN npm ci --only=production
# 3. Application code (changes frequently)
COPY . .
# 4. Metadata + runtime config
USER node
EXPOSE 3000
CMD ["dumb-init", "node", "server.js"]
.dockerignore
Always create one to reduce build context:
.git
node_modules
__pycache__
*.pyc
.vscode
.idea
.DS_Store
*.log
coverage/
.env
.env.local
dist/
build/
README.md
docs/
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.
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.
- 2d ago First seen · 601 lines · 49 tokens per session scan B f3635a22900c
docker is a skill published in the GitHub repository fellipeutaka/leon (5 stars, last pushed 4d ago), licensed MIT. It adds 49 tokens to every session and 3,806 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it B with 3 findings (asks for root, recursive force delete, 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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