Rules for building and testing a Ruby application with Docker, a tool that packages software and its environment, and GitHub Actions, an automated code-service workflow.

Use them to choose Docker files and services, build assets, run PostgreSQL and Redis, set application versions, and define CI/CD behavior.

They keep local development, tests, lint checks, staging, and production builds consistent across machines and deployments.

docker-ci — Cursor rule by romkey

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 rules/romkey/i2c-directory/docker-ci

Clone the repo

git clone --depth 1 https://github.com/romkey/I2C-Directory

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.

When invoked 615 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.

Model	Per session	Once invoked
Fable 5	$0.00000	$0.00615
Opus 5	$0.00000	$0.00308
Sonnet 5	$0.00000	$0.00123
Haiku 4.5	$0.00000	$0.00061

Measured 2d ago against content hash 7ec394d58cd1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

docker-ci 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.

.cursor/rules/docker-ci.mdc · 43 lines

How it starts

The opening of the file, as written. The whole thing — 43 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Docker and CI

Docker

Base image: ruby:4.0.5-slim with multi-stage build
Node: 24.x for asset compilation in production Dockerfile
Yarn: Use yarn install --immutable in production builds
Assets: Precompiled with SECRET_KEY_BASE_DUMMY=1
Runtime: Non-root rails user; entrypoint at bin/docker-entrypoint
Version: Pass APP_VERSION build arg from git tag in release workflow

docker-compose (split stacks)

Use -f docker-compose.<stack>.yml; each stack sets a top-level name: so volumes and networks do not collide.

File	Purpose
`docker-compose.dev.yml`	Local dev: Postgres + Redis + `web` + `sidekiq`. Postgres host port `5432`.
`docker-compose.test.yml`	Tests: thin Ruby image, bind-mounted app, cached Bundler volume; Postgres + Redis + `test` service.
`docker-compose.lint.build.yml`	Lint stack with `build:` for `Dockerfile.rubocop`.
`docker-compose.lint.yml`	RuboCop using prebuilt `links_rubocop:latest`.
`docker-compose.server.yml`	Prod/staging-style: external Postgres via `DATABASE_URL`; includes Redis for Sidekiq.

Dev startup: bin/dev runs db:prepare db:seed and clears stale PIDs before starting the server
Tests: docker compose -f docker-compose.test.yml run --rm test
Lint (quick): docker compose -f docker-compose.lint.yml run --rm rubocop
Lint (build): docker compose -f docker-compose.lint.build.yml run --rm rubocop
Server migrate: docker compose -f docker-compose.server.yml --profile tools run --rm migrate

GitHub Actions

ci.yml: Push/PR to main and staging; PostgreSQL 16 and Redis 8 services; runs Brakeman, bundler-audit, RuboCop, and bin/rails test
staging.yml: Push to staging; tests then builds/pushes :staging image to ghcr.io
release.yml: Push tag v*; tests then builds/pushes semver + :latest images with APP_VERSION from tag
Uses ruby/setup-ruby with bundler-cache and actions/setup-node with yarn cache
Concurrency: cancels in-progress runs for the same ref

Read the full file on GitHub · 43 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.

2d ago First seen · 43 lines · 0 tokens per session scan A 7ec394d58cd1

Subscribe to this mod's changes

docker-ci is a cursor rule published in the GitHub repository romkey/I2C-Directory (11 stars, last pushed 21d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 615 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 2026-08-30.

Databases DevOps and cloud Testing arduino esp32 esp8266 i2c i2c-bus twowire

docker-ci

Getting it into your agent

What it costs to keep this loaded

Grade A, and why

Nothing flagged

How it starts

Docker and CI

Docker

docker-compose (split stacks)

GitHub Actions

What this file has done since we first saw it

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