response-transformer

The response-transformer plugin modifies responses before they reach the client.

Overview

Phase: Response
Purpose: Transform response headers and body
Behavior: Applies transformations before returning to client

Configuration

{
  "pluginName": "response-transformer",
  "config": {
    "add": {
      "headers": ["X-Gateway-Version: 1.0"]
    },
    "set": {
      "headers": ["X-Response-Time: ${duration_ms}"]
    },
    "remove": {
      "headers": ["X-Internal-*"]
    },
    "rename": {
      "headers": ["X-Backend: X-Source"]
    }
  }
}

Transformation Types

Usage Example

Template Variables

Use variables in transformations:

Variable	Description
`${request_id}`	Unique request ID
`${duration_ms}`	Request duration (ms)
`${status}`	Response status code
`${consumer.id}`	Consumer ID (if auth)
`${route.id}`	Matched route ID
`${service.id}`	Matched service ID

Example:

{
  "set": {
    "headers": ["X-Response-Time: ${duration_ms}ms"]
  }
}

Body Transformation

Transform JSON response body fields:

{
  "add": {
    "body": ["gateway_processed: true"]
  },
  "remove": {
    "body": ["internal_metadata", "debug_info"]
  },
  "rename": {
    "body": ["backend_id: gateway_id"]
  }
}

Combining with request-transformer

Use both plugins for full request/response transformation:

# Request transformation
curl -X POST http://localhost:8080/api/plugins \
  -d '{"serviceId":"service_abc","pluginName":"request-transformer","config":{"add":{"headers":["X-Source: gateway"]}}}'

# Response transformation
curl -X POST http://localhost:8080/api/plugins \
  -d '{"serviceId":"service_abc","pluginName":"response-transformer","config":{"add":{"headers":["X-Via: gateway"]}}}'

Wildcard Patterns

Use * for pattern matching:

{
  "remove": {
    "headers": ["X-Backend-*", "X-Debug-*"]
  }
}

Removes all headers matching the pattern.

Regex Replacement

Use regex for complex replacements:

{
  "replace": {
    "headers": ["Server: Apache: MiniGateway"]
  }
}