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
• Integration tests with Testcontainers MongoDB
• 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

When to use this skill

• Add Mongock migrations in Spring Boot
• Review Spring MongoDB data migrations
• Configure Mongock change units for Spring Data MongoDB

Workflow

1. Read reference and inspect MongoDB setup

Read references/316-frameworks-spring-mongodb-migrations-mongock.md and inspect pom.xml, Spring Boot version, MongoDB configuration, 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, including Testcontainers-backed MongoDB migration checks where feasible, and summarize outcomes and follow-up risks.

Reference

For detailed guidance, examples, and constraints, see references/316-frameworks-spring-mongodb-migrations-mongock.md.