Multi Field Extraction

A single json_body_field filter extracts multiple top-level JSON fields into separate request headers in one pass

Category: Practical
Task: A single json_body_field filter extracts multiple top-level JSON fields into separate request headers in one pass

Prerequisites: The product runtime and any backend services referenced by this configuration.

Run it: Use ghcr.io/praxis-proxy/praxis:0.7.2 and follow the first reverse-proxy tutorial to mount and start the configuration.

This configuration comes from the selected release. The example has not been run here; external services are not bundled.

Download the source file.

# Multi-Field Extraction
#
# A single json_body_field filter extracts multiple top-level
# JSON fields into separate request headers in one pass. The
# body is parsed once regardless of how many fields are
# configured.
#
# This example extracts both "model" and "user_id" from an
# LLM API request body. The model header drives routing to
# the correct inference backend while the user ID is
# forwarded for upstream logging and rate limiting.
#
listeners:
  - name: inference-gateway
    address: "0.0.0.0:8080" # dev value; binds all interfaces
    filter_chains:
      - extract-fields
      - routing

filter_chains:
  - name: extract-fields
    filters:
      - filter: json_body_field
        fields:
          - field: model
            header: X-Model
          - field: user_id
            header: X-User-Id

  - name: routing
    filters:
      - filter: router
        routes:
          - path_prefix: "/"
            headers:
              x-model: "model-alpha-1"
            cluster: alpha_cluster
          - path_prefix: "/"
            headers:
              x-model: "model-alpha-2"
            cluster: alpha_v2
          - path_prefix: "/"
            cluster: default
      - filter: load_balancer
        clusters:
          - name: alpha_cluster
            endpoints:
              - "10.0.1.1:8080"
              - "10.0.1.2:8080"
          - name: alpha_v2
            endpoints:
              - "10.0.2.1:8080"
          - name: default
            endpoints:
              - "10.0.3.1:8080"