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Cache Processor

Overview​

The Write Cache processor provides a mechanism to stores API responses based on a defined keys, reducing redundant calls and improving performance.

WriteCache

Input and Output​

This processor operates on the response stream:

  • Input Stream: Response – The processor intercepts the response generated for a request and decides whether it should be cached based on the defined parameters.

  • Output Stream: Response – After processing, the response is either cached or passed along to the client, depending on the cache configuration.

By caching responses, the WriteCache processor ensures that frequently requested data can be served quickly without reprocessing the same requests, enhancing system efficiency and response time.

Parameters​

Each parameter is defined as a key-value pair inside the parameters section.

ttl_seconds​

Type: number
Required: False
Default: 600 (10 minutes)
Time to live for the cache entry in seconds.

Example:

- key: ttl_seconds
  value: 600

record_max_size_bytes​

Type: number
Required: False
Default: -1 (unlimited)
Defines the maximum size of the cached record in bytes.

Example:

- key: record_max_size_bytes
  value: 32768

max_cache_size_mb​

Type: number
Required: False
Default: 100 MB
Defines how much cache space is used by this processor in MB.

Example:

- key: max_cache_size_mb
  value: 200

caching_key_parts​

Type: list_of_strings
Required: True
Defines the list of request attributes used to generate a unique cache key. This ensures that different request variations (e.g., different headers or body parameters) result in separate cache entries.

Example:

- key: caching_key_parts
  value:
    - $.request.headers.x_api_key
    - $.request.body.ID

Best Practices​

  • Ensure caching_key_parts is consistent between Read Cache and Write Cache processors.
  • Use an appropriate ttl_seconds to balance cache freshness and efficiency.
  • Set max_cache_size_mb and record_max_size_bytes based on available memory and response sizes.
  • Be mindful of API responses that contain sensitive data—avoid caching if necessary.

For more details on configuring Caching flows, visit the Lunar.dev Flows Documentation.

Example Usage​

CacheWrite:
  processor: WriteCache
  parameters:
    - key: ttl_seconds
      value: 600
    - key: record_max_size_bytes
      value: -1
    - key: max_cache_size_mb
      value: 100
    - key: caching_key_parts
      value:
        - $.request.headers.x_api_key
        - $.request.body.ID

For the example request:

 {
  "headers": {
    "x_api_key": "12345ABC"
  },
  "body": {
    "ID": "67890XYZ"
  }
}

The generated Cache key will be 12345ABC:67890XYZ. This means that a different x_api_key or ID combination will produce a different cache key, ensuring proper cache differentiation based on request variations.