dockerfile-maven-build-without-cache-mount

Warnings require a CI-discovered build with a recognized persistent builder path: Depot, configured Blacksmith, or repository-visible Buildkite local Docker state persistence. Unknown/disposable builders are not flagged for missing cache mounts.

Detects Java Dockerfiles that run Maven build goals without a visible BuildKit cache mount on the same instruction.

This rule looks for:

• a qualifying persistent Docker build discovered from GitHub Actions or Buildkite
• pom.xml in the build context
• RUN mvn package, RUN mvn clean package, RUN mvn install, or RUN mvn verify through mvn, mvnw, or ./mvnw
• no --mount=type=cache on that Dockerfile instruction

Why it matters:

• Maven builds reuse downloaded dependencies and plugins from the local repository.
• Without a BuildKit cache mount such as /root/.m2, Docker rebuilds can repeatedly pay dependency and plugin download costs.

What to do:

• Add a BuildKit cache mount for /root/.m2 to the Maven build step.
• Keep dependency resolution and application build steps separated when practical.

This rule intentionally does not require tests to be skipped or a specific Maven version.