316-frameworks-spring-mongodb-migrations-mongock - Claude MCP Skill

# Spring - MongoDB migrations (Mongock)

Apply Mongock migration guidelines for Spring Boot and Spring Data MongoDB.

**What is covered in this Skill?**

- Mongock BOM, Spring Boot runner, and Spring Data MongoDB driver coordinates
- `mongock.migration-scan-package` configuration and startup execution
- Code-first `@ChangeUnit` migrations with `@Execution` and rollback hooks
- Locking, idempotency, transaction limits, and forward-only rollout discipline
- Optional MongoDB-backed integration tests using only project-approved, pinned, or already-available container images when the user permits external runtime dependencies
- Coordination with `@315-frameworks-spring-mongodb`

**Scope:** Apply recommendations based on the reference rules and good/bad examples.

## Constraints

Compile before Mongock or MongoDB migration changes; verify after changes.

- **MANDATORY**: Run `./mvnw compile` or `mvn compile` before applying any change
- **SAFETY**: If compilation fails, stop immediately
- **VERIFY**: Run `./mvnw clean verify` or `mvn clean verify` after applying improvements
- **BEFORE APPLYING**: Read the reference for detailed rules and good/bad patterns
- **EDGE CASE**: If the project Spring Data MongoDB version is not compatible with the selected Mongock driver, stop and ask whether to pin/upgrade Mongock or use a lower driver generation
- **EXTERNAL RUNTIME GATE**: Do not pull or execute Docker images for MongoDB verification unless the user explicitly approves and the image is pinned, policy-approved, or already present in the project configuration

## When to use this skill

- Add Mongock migrations in Spring Boot
- Review Spring MongoDB data migrations
- Configure Mongock change units for Spring Data MongoDB
- Create Mongock change units for Spring Boot MongoDB
- Review Mongock migration ordering in a Spring service

## Workflow

1. **Read references and inspect MongoDB setup**

Read `references/316-frameworks-spring-mongodb-migrations-mongock.md`, `references/316-frameworks-spring-mongodb-migrations-mongock-antipatterns.md`, and `references/316-frameworks-spring-mongodb-migrations-mongock-parallel-change.md`, then inspect `pom.xml`, Spring Boot version, dependency management, MongoDB configuration, existing full-context tests, and existing `@315-frameworks-spring-mongodb` persistence patterns.

2. **Choose runner, driver, and execution policy**

Select Mongock coordinates compatible with the active Spring Data MongoDB generation, configure migration scan packages, and decide startup vs controlled-job execution.

3. **Apply framework-aligned migrations**

Implement/refactor `@ChangeUnit` classes with idempotent operations, explicit ordering, rollback hooks, and safe lock/transaction settings.

4. **Run verification and report results**

Execute build/tests. Run MongoDB-backed migration checks only when the project already defines an approved MongoDB test runtime or the user explicitly approves a pinned container image. If generic `@SpringBootTest` smoke tests do not provide MongoDB, disable Mongock only for those tests with `mongock.enabled=false`. Summarize outcomes and follow-up risks.

## Reference

For detailed guidance, examples, and constraints, see:

- [references/316-frameworks-spring-mongodb-migrations-mongock.md](references/316-frameworks-spring-mongodb-migrations-mongock.md)
- [references/316-frameworks-spring-mongodb-migrations-mongock-antipatterns.md](references/316-frameworks-spring-mongodb-migrations-mongock-antipatterns.md)
- [references/316-frameworks-spring-mongodb-migrations-mongock-parallel-change.md](references/316-frameworks-spring-mongodb-migrations-mongock-parallel-change.md)