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/kid-sid/codex-spellbook/dockernpx skills add kid-sid/codex-spellbook --skill dockergit clone --depth 1 https://github.com/kid-sid/codex-spellbookWhat 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 | $0.00039 | $0.00598 |
| Opus 5 | $0.00019 | $0.00299 |
| Sonnet 5 | $0.00008 | $0.00120 |
| Haiku 4.5 | $0.00004 | $0.00060 |
Grade A, and why
docker 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 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.
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 — 101 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Docker
Build minimal, reproducible images that start fast, run as non-root, and separate build-time concerns from runtime behavior.
When to Activate
- Write or refactor a Dockerfile
- Split build and runtime concerns
- Harden a container for production
- Improve Docker build cache performance
- Add container healthchecks
- Review secret handling in image builds
- Shrink image size and attack surface
Base Images and Layering
| Use Case | Preferred | Avoid |
|---|---|---|
| Production service | Distroless or slim runtime | Full distro with build toolchain |
| Build stage | Language-specific SDK image | Installing compilers in runtime image |
| Tiny static binary | scratch when feasible |
Heavy general-purpose images |
| Order | Reason |
|---|---|
| Copy lockfiles first | Maximizes dependency cache hits |
| Install dependencies | Expensive step stays cached |
| Copy source later | Code changes do not bust dependency layer |
Runtime Hardening
BAD
FROM python:3.12-slim
WORKDIR /app
COPY . .
CMD ["python", "main.py"]
GOOD
FROM python:3.12-slim AS runtime
WORKDIR /app
RUN useradd --create-home appuser
COPY --chown=appuser:appuser . .
USER appuser
CMD ["python", "main.py"]
| Scenario | Rule |
|---|---|
| Build-time private dependency access | Use ephemeral build secrets if available |
| Runtime credentials | Inject via environment or secret store |
| Static secret in Dockerfile | Never do it |
| Preferred | Avoid |
|---|---|
| Application-level readiness endpoint | Checking only whether PID exists |
| Fast, dependency-light command | Heavy scripts that change container state |
Ignore List
| Always Ignore |
|---|
.git |
node_modules |
.venv |
| test artifacts |
local secrets and .env files |
BAD
COPY . .
RUN npm install
GOOD
COPY package.json pnpm-lock.yaml ./
RUN pnpm install --frozen-lockfile
COPY . .
Checklist
- Dockerfile uses multi-stage builds when build tooling is required
- Dependency layers are copied before application source
- Runtime image uses a non-root user
-
.dockerignoreexcludes local junk and secrets - Secrets are injected at runtime or via build secret facilities
- Healthcheck verifies real service readiness
- Base image is minimal for the workload
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 · 101 lines · 39 tokens per session scan A 69ceaf6194d7
docker is a skill published in the GitHub repository kid-sid/codex-spellbook (21 stars, last pushed 3mo ago), licensed MIT. It adds 39 tokens to every session and 598 once invoked, about $0.0002 per session on Opus 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 2026-08-30.
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