Improve local DX & testing: Postgres via Docker/Testcontainers + OpenAPI & metrics + security headers

[Akhilkumar31]

Problem:

• H2-based dev/test diverges from production-like setups
• Limited observability
• Minimal default security headers

Solution:

• docker-compose.yml + application-postgres.yml for one-command Postgres
• Testcontainers for realistic, isolated integration tests
• springdoc OpenAPI for discoverable endpoints; Micrometer Prometheus for metrics
• Opinionated security headers (CSP/XSS/frame/referrer)

How to test:

1. docker compose up -d db
2. ./mvnw spring-boot:run -Dspring-boot.run.profiles=postgres
3. ./mvnw -q test # runs unit + Testcontainers ITs

Verify:

• http://localhost:8080/swagger-ui.html
• http://localhost:8080/actuator/health
• http://localhost:8080/actuator/prometheus

Impact:

• Faster onboarding
• More reliable tests
• Easier ops handoff
• Safer defaults

[andrzejsydor]

What about assertions of other fields?

[Akhilkumar31]

Addressed: the test asserts id, first/last name, address, city, telephone (and pets empty). Also added a negative lookup case.

[Akhilkumar31]

Rebased onto latest main and kept upstream docker-compose as-is.
Integration test now asserts all seeded fields and includes a negative case.
Formatting applied; local Maven + Testcontainers run is green.