Stream Buffer

json_body_field inspects request body chunks as they arrive and defers upstream forwarding until the field is extracted (or end-of-stream)

Category: Practical
Task: json_body_field inspects request body chunks as they arrive and defers upstream forwarding until the field is extracted (or end-of-stream)

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.

# Stream-Buffer Body Inspection with Action-Based Routing
#
# json_body_field inspects request body chunks as they arrive
# and defers upstream forwarding until the field is extracted
# (or end-of-stream). The extracted value is promoted to a
# request header, which the router then matches on to select
# the correct backend cluster.
#
listeners:
  - name: web
    address: "0.0.0.0:8080" # dev value; binds all interfaces
    filter_chains:
      - body-inspection
      - routing

filter_chains:
  # Extract the "action" field from the JSON body and promote
  # it to the X-Action request header. StreamBuffer mode
  # accumulates chunks and defers forwarding until extraction
  # completes.
  - name: body-inspection
    filters:
      - filter: json_body_field
        field: action
        header: X-Action

  # Route based on the promoted X-Action header.
  - name: routing
    filters:
      - filter: router
        routes:
          - path_prefix: "/"
            headers:
              x-action: "process"
            cluster: processor
          - path_prefix: "/"
            headers:
              x-action: "validate"
            cluster: validator
          - path_prefix: "/"
            cluster: default
      - filter: load_balancer
        clusters:
          - name: processor
            endpoints:
              - "127.0.0.1:3001"
              - "127.0.0.1:3002"
          - name: validator
            endpoints:
              - "127.0.0.1:3003"
          - name: default
            endpoints:
              - "127.0.0.1:3000"

# Global body size ceiling (10 MB).
body_limits:
  max_request_bytes: 10485760

insecure_options:
  allow_private_endpoints: true # example proxies to local backends