docker

When to Use

• Writing or reviewing a Dockerfile
• Setting up compose for dev/test/prod
• Optimizing image size or build time
• Container security, networking, or volume management
• Containerizing a Spring Boot application

Engine agnosticism

Everything in this skill is spec OCI: the Dockerfile, the multi-stage build, the Compose spec files, and the feature flags shown run unchanged on Docker or Podman. The examples use docker CLI; substitute podman or lean on the podman-docker shim where it exists.

• Dockerfile semantics: Docker (BuildKit) ≈ Podman (Buildah). No docker-only Dockerfile instructions are used here.
• Compose: prefer the Compose spec files (compose.yaml) and a Compose v2 client. docker compose (v2.22+) works against a Podman socket via DOCKER_HOST; podman-compose implements less of the spec (notably no watch).
• Image scanning: trivy is the engine-neutral default (next section).
• Image versions in the examples below are illustrative (e.g. postgres:16-alpine); the production version is a project decision recorded in the project docs, not a rule of this skill.

Instructions