Flow Example

This is an example of a fully configured Caching Flow that caches API responses based on URL patterns and headers, ensuring faster response times and reduced load on API providers.

/etc/lunar-proxy/flows/caching-flow-example.yaml

name: CachingFlowExample

filter:
  url: api.example.com/v1/resource/* # Caches responses for API endpoints matching this pattern.

processors:
  ReadCache:
    processor: ReadCache # Reads cached responses if available.
    parameters:
      - key: normalized_path_key
        value: "api.example.com/v1/resource"
      - key: header_key
        value: "Authorization" # Example: Authorization header used for cache keys.
      - key: path_parameter_key
        value: "resourceID" # Example: Path parameter used for cache keys.

  WriteCache:
    processor: WriteCache # Writes responses to the cache.
    parameters:
      - key: ttl_seconds
        value: 300 # Cache time-to-live set to 5 minutes.
      - key: record_max_size_bytes
        value: 4096 # Maximum size of cached responses is 4 KB.
      - key: max_cache_size_megabytes
        value: 100 # Cache size limited to 100 MB.
      - key: normalized_path_key
        value: "api.example.com/v1/resource"
      - key: header_key
        value: "Authorization"
      - key: path_parameter_key
        value: "resourceID"

flow:
  request:
    - from:
        stream:
          name: globalStream
          at: start
      to:
        processor:
          name: ReadCache

    - from:
        processor:
          name: ReadCache
          condition: cache_miss
      to:
        stream:
          name: globalStream
          at: end

  response:
    - from:
        stream:
          name: globalStream
          at: start
      to:
        processor:
          name: WriteCache

    - from:
        processor:
          name: WriteCache
      to:
        stream:
          name: globalStream
          at: end

    - from:
        processor:
          name: ReadCache
          condition: cache_hit
      to:
        stream:
          name: globalStream
          at: end

Troubleshooting

1. Cache Misses:

   • Verify that the normalized_path_key and header_key parameters match the actual request values.
   • Check that the path_parameter_key is properly configured to align with API request parameters.

2. Excessive Cache Size:

   • Confirm that max_cache_size_megabytes and ttl_seconds are appropriately set.
   • Reduce record_max_size_bytes if individual cache entries are too large.

3. Incorrect Cached Responses:

   • Check the WriteCache processor configuration to ensure responses are being cached correctly.
   • Validate that key selectors (headers, path parameters) used for cache keys are accurate and unique.