Add cache to DynamoDB App Manager

[lilfaf]

The DynamoDB App Manager was missing in-memory caching, causing every find_by_id() call to query DynamoDB directly.

• Add Moka cache with configurable TTL and max capacity
• Cache apps on create, update, and retrieval
• Invalidate cache on delete
• Support global CACHE_TTL_SECONDS and CACHE_MAX_CAPACITY env vars
• Add DynamoDB Local to docker-compose.test.yml and CI workflow
• Add unit tests for cache behavior, invalidation, and TTL expiration

This matches the caching pattern already used in other app managers.

Description

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Code refactoring

Testing

• Unit tests pass
• Integration tests pass
• Manual testing completed

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published

Build Artifacts

Additional Notes

[gemini-code-assist]

Summary of Changes

Hello @lilfaf, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the performance of the DynamoDB App Manager by integrating an in-memory caching layer. This change aims to minimize direct calls to DynamoDB for frequently accessed application data, thereby improving response times and reducing the load on the database. The caching mechanism is designed to be highly configurable and aligns with existing caching strategies within the system, ensuring consistency and maintainability.

Highlights

• In-Memory Caching: Introduced in-memory caching using the moka library for the DynamoDB App Manager to reduce direct database queries.
• Configurable Cache Settings: Added configurable Time-To-Live (TTL) and maximum capacity for the cache, which can be set via global environment variables CACHE_TTL_SECONDS and CACHE_MAX_CAPACITY.
• Cache Management: Implemented cache-aside logic where apps are cached upon creation, update, and retrieval, and explicitly invalidated (removed) from the cache upon deletion.
• Local Testing Environment: Integrated DynamoDB Local into docker-compose.test.yml and the CI workflow, enabling robust local testing of DynamoDB interactions and cache behavior.
• Comprehensive Unit Tests: Added extensive unit tests to verify the correct functioning of the cache, including its behavior on hits, misses, invalidation, and TTL expiration.

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Ignored Files

• Ignored by pattern: .github/workflows/** (1)
  • .github/workflows/ci.yml

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[gemini-code-assist]

Code Review

This pull request introduces a caching layer using the moka library for the DynamoDbAppManager to improve performance by caching application data. The changes include adding cache_ttl and cache_max_capacity configuration options, integrating cache lookup and population into find_by_id, create_app, update_app, and find_by_key methods, and invalidating cache entries on delete_app. A local DynamoDB service was added to docker-compose.test.yml along with extensive unit tests to verify the cache's behavior, including hits, misses, expiration, and invalidation. Review comments suggest changing the cache invalidation method from remove to invalidate in delete_app for better API adherence and removing cache population from the get_apps method to prevent cache churn and high memory usage, recommending organic cache warming instead.