Proposal: auto-label containers with test class/field when managed by @Testcontainers

[lekhrocks]

Problem

When running a test suite with @Testcontainers, docker ps shows containers with auto-generated names like tc-hs89alkj27d-postgres. There's no way to tell which container belongs to which test without cross-referencing container IDs against test output.

Proposal

Set two Docker labels on every container started via @testcontainers:

  testcontainers/test-class  →  "com.example.MyPostgresTest"
  testcontainers/test-field  →  "postgresContainer"

These labels are set in the JUnit extension's StoreAdapter.start() before calling container.start(). They use the public withLabel() API.

What it enables

• docker ps --filter label=testcontainers/test-class=com.example.MyPostgresTest
• CI error output becomes grep-able by test class name
• No new API surface, no config needed, no behavioral change

Questions for the maintainers

1. Is the testcontainers/ prefix acceptable, or would you prefer a different namespace?
2. Should this be opt-in via a @Testcontainers(enableLabels=true) attribute, or always-on?
3. Any concerns about label cardinality in long-running test suites?