Envoy tracing custom_tags modifying x-request-id

README.md

Envoy is changing the x-request-id version when we configure the connection manager with:

tracing: {}

I configured Envoy with the upstream cluster pointing to postman-echo.com which will return as response body, the request headers sent.

curl --location --request GET 'localhost:8080/headers' \
--header 'x-request-id: 968ea8f8-3806-45c9-8228-8d3dde5df3b4' \
--header 'x-another-id: 968ea8f8-3806-45c9-8228-8d3dde5df3b4'

{
    "headers":{
        "x-forwarded-proto":"http",
        "x-forwarded-port":"80",
        "host":"localhost",
        "x-amzn-trace-id":"Root=1-5f97d990-6daf0ed27c296cad5e916f6c",
        "content-length":"0",
        "user-agent":"curl/7.64.1",
        "accept":"*/*",
        "x-request-id":"968ea8f8-3806-95c9-8228-8d3dde5df3b4",
        "x-another-id":"968ea8f8-3806-45c9-8228-8d3dde5df3b4",
        "x-envoy-expected-rq-timeout-ms":"15000"
    }
}

-968ea8f8-3806-45c9-8228-8d3dde5df3b4
+968ea8f8-3806-95c9-8228-8d3dde5df3b4

My use case is the one below, as I need to copy the x-request-id as a tag:

tracing:
  custom_tags:
    - tag: x-request-id
        request_header:
        name: x-request-id

But as you can try it out here, only by adding an empty tracing: {} the problem happens.

Also, the problem only happens with the x-request-id, as you can see I used also a x-another-id and that one did not change.

docker-compose.yaml

version: '3'
services:
  envoy:
    image: envoyproxy/envoy:v1.16-latest
    ports:
      - "8080:8080"
    volumes:
      - ./envoy.yaml:/opt/envoy.yaml
    entrypoint:
      - sh
      - -c
      - /usr/local/bin/envoy -c /opt/envoy.yaml
      

envoy.yaml

static_resources:
  listeners:
  - name: main
    address:
      socket_address:
        address: 0.0.0.0
        port_value: 8080
    filter_chains:
    - filters:
      - name: envoy.http_connection_manager
        config:
          stat_prefix: ingress_http
          codec_type: auto
          generate_request_id: true
          preserve_external_request_id: true
          tracing: {}
          route_config:
            name: local_route
            virtual_hosts:
            - name: local_service
              domains:
              - "*"
              routes:
              - match:
                  prefix: "/"
                route: 
                  cluster: echo_service
          http_filters:
          - name: envoy.router
            config: {}

  clusters:
  - name: echo_service
    connect_timeout: 0.25s
    type: STRICT_DNS
    lb_policy: ROUND_ROBIN
    hosts:
    - socket_address:
        address: postman-echo.com
        port_value: 80

admin:
  access_log_path: "/dev/null"
  address:
    socket_address:
      address: 0.0.0.0
      port_value: 8001