feat: add Dockerfile and .dockerignore for containerized builds

[felipementel]

Why

This project had no container support, making it harder to run consistently across environments. Adding a Dockerfile and .dockerignore enables building and running the API as a Docker image with a reproducible, production-ready setup.

What changed

A multi-stage build approach is used to keep the final image lean:

• Stage 1 (build) — eclipse-temurin:21-jdk-alpine: copies the Maven wrapper and pom.xml first to leverage Docker layer caching for dependencies (dependency:go-offline), then copies src/ and produces the fat JAR via mvnw clean package -DskipTests.
• Stage 2 (runtime) — eclipse-temurin:21-jre-alpine: copies only the built JAR, runs it as a non-root user (appuser) for security, exposes port 8080, and includes a HEALTHCHECK against /actuator/health.

The .dockerignore excludes build artifacts (target/), IDE files, docs, and VCS metadata to keep the build context small and avoid accidentally invalidating cache layers.

Notes

• The HEALTHCHECK probes /actuator/health — add spring-boot-starter-actuator to pom.xml if not already present, or update the endpoint accordingly.
• No packages are installed in the runtime stage, so apk --no-cache is not needed there.

[Copilot]

Pull request overview

Adds initial containerization support for the Spring Boot API so it can be built and run reproducibly via Docker using a multi-stage build.

Changes:

• Introduces a multi-stage Dockerfile (build with Maven wrapper; runtime with non-root user and healthcheck).
• Adds a .dockerignore to reduce build context size and improve caching.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
Dockerfile	Multi-stage build/runtime image definition for the API container.
.dockerignore	Excludes common build artifacts/IDE/VCS files from Docker build context.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

The HEALTHCHECK targets /actuator/health, but this repo currently doesn't include spring-boot-starter-actuator (and the codebase already exposes /health/live and /health/ready). As written, containers will be marked unhealthy due to a 404. Update the HEALTHCHECK to hit an existing endpoint (e.g. /health/ready) or add Actuator and ensure the endpoint is enabled in config.

Suggested change

	CMD wget --no-verbose --tries=1 --spider http://localhost:8080/actuator/health || exit 1
	CMD wget --no-verbose --tries=1 --spider http://localhost:8080/health/ready || exit 1

[Copilot]

The runtime stage copies a version-pinned JAR name (usuarios-api-java-0.1.0.jar). This will break the Docker build whenever the project version changes or if the artifact name is customized. Consider producing a stable output name during the build (e.g., configure Maven finalName to app) and copy that, or otherwise avoid hard-coding the version in the Dockerfile.

Suggested change

	COPY --from=build /app/target/usuarios-api-java-0.1.0.jar app.jar
	COPY --from=build /app/target/*.jar app.jar

[Copilot]

You can avoid the extra layer from RUN chown ... by using COPY --chown=appuser:appgroup --from=build ... app.jar when copying the JAR into the runtime image. This keeps the image slightly smaller and the Dockerfile simpler.

Suggested change

	COPY --from=build /app/target/usuarios-api-java-0.1.0.jar app.jar
	RUN chown appuser:appgroup app.jar
	COPY --chown=appuser:appgroup --from=build /app/target/usuarios-api-java-0.1.0.jar app.jar