i’d like to set up a tcp reverse-proxy with traefik and trace the connections with OpenTelemetry.

I’ve set up jaeger, traefik and the traefik-whoami test enedpoint and with HTTP routers I got everything working as expected – the correct http response is returned and some traces appear in jaeger (spans for the entrypoint, the router, … up to the reverse proxy invocation – enough for me for now…).

For the TCP-based router, the reverse proxy also works as intended, however, no traces appear in jaeger. I’m aware of the limitations and implications of the TCP-based routing and tracing, like no propagation etc.; but I’d be more than happy with just the traefik internal spans.

I use this docker-compose based setup.

kind regards!

version: "3"
services:
  jaeger:
    image: jaegertracing/all-in-one
    ports:
      - "16686:16686"
  traefik:
    image: traefik:v3.1.3
    volumes:
      - ./traefik_cfg/:/etc/traefik/
    ports:
      - "9000:9000"
      - "18080:80"
  whoami:
    image: traefik/whoami
    ports:
      - "28080:80"

# traefik.toml 
[global]
checkNewVersion = false
sendAnonymousUsage = false

[log]
level = "DEBUG"

[api]
dashboard = true
insecure = true

[entryPoints]
[entryPoints.web]
address = ":80"
[entryPoints.tcp]
address = ":9000"

[providers]
[providers.file]
filename = "/etc/traefik/dynamic_conf.toml"


[tracing]
addInternals = true
[tracing.otlp.grpc]
endpoint = "jaeger:4317"
insecure = true

# dynamic_conf.toml
[tcp]
  [tcp.routers]
    [tcp.routers.whoami-tcp]
      entryPoints = ["tcp"]
      rule = "HostSNI(`*`)"
      service = "whoami-tcp-svc"

    [tcp.services.whoami-tcp-svc.loadBalancer]
      [[tcp.services.whoami-tcp-svc.loadBalancer.servers]]
        address = "whoami:80"


[http.routers]
  [http.routers.whoami-http]
    entryPoints = ["web"]
    rule = "PathPrefix(`/whoami`)"
    service = "whoami-http-svc"

[http.services]
  [http.services.whoami-http-svc]
    [http.services.whoami-http-svc.loadBalancer]
      [[http.services.whoami-http-svc.loadBalancer.servers]]
        url = "http://whoami:80"