# Dockerfile

> Use when editing tracked Backstage, agent, MCP, or Golden Path Dockerfiles.

- Skill: `paulasilvatech/dockerfile` (Agent Skill)
- Install (CLI): `npx skillmds@latest add paulasilvatech/dockerfile`
- Raw SKILL.md: https://api.skillmd.com/api/skills/paulasilvatech/dockerfile/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: paulasilvatech (https://skillmd.com/u/paulasilvatech)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/paulasilvatech/dockerfile

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<!-- Generated from harness/github-copilot/plugins/open-horizons-platform/instructions/dockerfile.instructions.md by harness/claude-code/scripts/convert_from_copilot.py. Edit the source, not this file. -->

# Dockerfiles

## Conventions

- Pin base images to an explicit supported version; production Dockerfiles must not use `latest`.
- Use multi-stage builds so compilers, caches, tests, and development dependencies stay out of the runtime image.
- Copy dependency manifests before source to preserve cacheability and use the package manager matching the lockfile.
- Run the final process as a non-root user with only required files and writable directories.
- Keep credentials out of `ARG`, `ENV`, layers, build context, and package-manager configuration; use build secrets only in approved CI.
- Use exec-form entrypoints, propagate termination signals, and expose only documented service ports.
- Minimize packages, remove caches in the same layer, and keep runtime versions aligned with local manifests.
- Keep health behavior consistent with Compose and Kubernetes probes rather than adding a conflicting endpoint.

## Verification

- The intended target builds from a clean context.
- Image inspection confirms the non-root user, pinned base, and absence of secret material.
- The container starts and responds on its documented health endpoint.

## Do / Do Not

| Do | Do not |
| --- | --- |
| Pin base images, minimize build context, and execute as a non-root user. | Bake credentials, mutable bases, or unnecessary build artifacts into an image. |
| Keep health behavior aligned with deployed probes. | Add a conflicting or artificial health endpoint. |

## Checklist Before Opening a PR

- [ ] The change matches this instruction's `applyTo` scope.
- [ ] The intended target builds from a clean context.
- [ ] Image inspection verifies the base, user, and absence of secrets.
- [ ] The container responds on the documented health endpoint.
- [ ] No unrelated edits or unresolved placeholders remain.