[#6] Event Store service: Kafka -> PostgreSQL persistence

[igorsatsyuk]

Description

Implements Event Store Service for issue #6: consumes user.login.events from Kafka and persists immutable events to PostgreSQL audit.events via R2DBC.

What was done

• Added reactive persistence layer (StoredAuditEvent, StoredAuditEventRepository, EventPersistenceService)
• Added Kafka consumer (UserLoginEventConsumer) and listener configuration
• Added SHA-256 hash calculation service for persisted payloads
• Added/updated service configuration (application.yml, ObjectMapper/Kafka config)
• Added migration readiness and module documentation (backend/event-store-service/README.md)
• Added unit + integration tests, including Testcontainers Kafka -> PostgreSQL e2e scenario
• Marked #6.1–#6.5 as completed in GITHUB_ISSUES_PLAN.md

Closes

• Closes [BACKEND] Event Store - сервис записи в БД #6

Checklist

• Code follows style guidelines
• Self-review completed
• Tests added/updated
• Documentation updated

Testing

mvn -f backend/pom.xml -pl event-store-service test

[Copilot]

Pull request overview

Implements Issue #6 by adding a Kafka → PostgreSQL persistence pipeline to event-store-service. The service consumes user.login.events from Kafka, maps AuditEvents into a StoredAuditEvent JPA-like R2DBC entity (with a SHA-256 payload hash and stable event_hash/event_id), and writes them to the audit.events table via Spring Data R2DBC. An end‑to‑end Testcontainers integration test plus focused unit tests are added.

Changes:

• Add Kafka listener (UserLoginEventConsumer), persistence service (EventPersistenceService), SHA-256 hashing service, R2DBC entity/repository, and Kafka/Jackson configuration.
• Add unit tests for hashing, persistence mapping, consumer dispatch, and a Kafka↔PostgreSQL Testcontainers integration test.
• Update application.yml default JSON type, pom.xml (drop runtime scope on r2dbc-postgresql, add testcontainers:junit-jupiter), README.md, and GITHUB_ISSUES_PLAN.md.

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
GITHUB_ISSUES_PLAN.md	Mark Issue #6 subtasks as done.
backend/event-store-service/pom.xml	Promote r2dbc-postgresql to compile scope; add Testcontainers JUnit Jupiter dependency.
backend/event-store-service/README.md	New module documentation covering run & test commands.
backend/event-store-service/src/main/resources/application.yml	Switch Kafka default JSON type from abstract AuditEvent to UserLoggedInEvent.
backend/event-store-service/src/main/java/.../EventStoreServiceApplication.java	Enable Kafka listeners via @EnableKafka.
backend/event-store-service/src/main/java/.../config/JacksonConfig.java	Provide a configured ObjectMapper bean.
backend/event-store-service/src/main/java/.../config/KafkaListenerConfig.java	Define explicit consumer factory and listener container factory.
backend/event-store-service/src/main/java/.../config/KafkaTopicsProperties.java	Configuration-properties holder for topic names (currently unused).
backend/event-store-service/src/main/java/.../consumer/UserLoginEventConsumer.java	@KafkaListener that delegates to persistence service.
backend/event-store-service/src/main/java/.../model/StoredAuditEvent.java	R2DBC entity mapped to audit.events.
backend/event-store-service/src/main/java/.../repository/StoredAuditEventRepository.java	Reactive CRUD repository.
backend/event-store-service/src/main/java/.../service/EventHashService.java	SHA-256 hex digest helper.
backend/event-store-service/src/main/java/.../service/EventPersistenceService.java	Maps events to entities, retries, dedupes duplicates, persists.
backend/event-store-service/src/test/java/.../service/EventHashServiceTest.java	Unit test for SHA-256 output.
backend/event-store-service/src/test/java/.../service/EventPersistenceServiceTest.java	Unit tests for mapping and duplicate-key handling.
backend/event-store-service/src/test/java/.../consumer/UserLoginEventConsumerTest.java	Consumer dispatch unit tests.
backend/event-store-service/src/test/java/.../EventStoreKafkaToPostgresIntegrationTest.java	Testcontainers-based Kafka→PostgreSQL integration test.

---

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

[Copilot]

Pull request overview

Copilot reviewed 17 out of 17 changed files in this pull request and generated no new comments.