Jaeger Native Tracing

The Jaeger tracing sandbox demonstrates Envoy’s request tracing capabilities using Jaeger as the tracing provider and Jaeger’s native C++ client as a plugin. Using Jaeger with its native client instead of with Envoy’s builtin Zipkin client has the following advantages:

  • Trace propagation will work with the other services using Jaeger without needing to make configuration changes.

  • A variety of different sampling strategies can be used, including probabilistic or remote where sampling can be centrally controlled from Jaeger’s backend.

  • Spans are sent to the collector in a more efficient binary encoding.

This sandbox is very similar to the front proxy architecture described above, with one difference: service1 makes an API call to service2 before returning a response. The three containers will be deployed inside a virtual network called envoymesh. (Note: the sandbox only works on x86-64).

All incoming requests are routed via the front Envoy, which is acting as a reverse proxy sitting on the edge of the envoymesh network. Port 80 is mapped to port 8000 by docker compose (see /examples/jaeger-native-tracing/docker-compose.yaml). Notice that all Envoys are configured to collect request traces (e.g., http_connection_manager/config/tracing setup in /examples/jaeger-native-tracing/front-envoy-jaeger.yaml) and setup to propagate the spans generated by the Jaeger tracer to a Jaeger cluster (trace driver setup in /examples/jaeger-native-tracing/front-envoy-jaeger.yaml).

Before routing a request to the appropriate service Envoy or the application, Envoy will take care of generating the appropriate spans for tracing (parent/child context spans). At a high-level, each span records the latency of upstream API calls as well as information needed to correlate the span with other related spans (e.g., the trace ID).

One of the most important benefits of tracing from Envoy is that it will take care of propagating the traces to the Jaeger service cluster. However, in order to fully take advantage of tracing, the application has to propagate trace headers that Envoy generates, while making calls to other services. In the sandbox we have provided, the simple flask app (see trace function in /examples/front-proxy/service.py) acting as service1 propagates the trace headers while making an outbound call to service2.

Running the Sandbox

The following documentation runs through the setup of an Envoy cluster organized as is described in the image above.

Step 1: Build the sandbox

To build this sandbox example, and start the example apps run the following commands:

  1. $ pwd
  2. envoy/examples/jaeger-native-tracing
  3. $ docker-compose pull
  4. $ docker-compose up --build -d
  5. $ docker-compose ps
  7.             Name                              Command                State                                                      Ports
  8. -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  9. jaeger-native-tracing_front-envoy_1   /start-front.sh                Up      10000/tcp, 0.0.0.0:8000->80/tcp, 0.0.0.0:8001->8001/tcp
  10. jaeger-native-tracing_jaeger_1        /go/bin/all-in-one-linux - ... Up      14250/tcp, 14268/tcp, 0.0.0.0:16686->16686/tcp, 5775/udp, 5778/tcp, 6831/udp, 6832/udp, 0.0.0.0:9411->9411/tcp
  11. jaeger-native-tracing_service1_1      /start-service.sh              Up      10000/tcp, 80/tcp
  12. jaeger-native-tracing_service2_1      /start-service.sh              Up      10000/tcp, 80/tcp

Step 2: Generate some load

You can now send a request to service1 via the front-envoy as follows:

  1. $ curl -v localhost:8000/trace/1
  2. *   Trying 192.168.99.100...
  3. * Connected to 192.168.99.100 (192.168.99.100) port 8000 (#0)
  4. > GET /trace/1 HTTP/1.1
  5. > Host: 192.168.99.100:8000
  6. > User-Agent: curl/7.54.0
  7. > Accept: */*
  8. >
  9. < HTTP/1.1 200 OK
  10. < content-type: text/html; charset=utf-8
  11. < content-length: 89
  12. < x-envoy-upstream-service-time: 9
  13. < server: envoy
  14. < date: Fri, 26 Aug 2018 19:39:19 GMT
  15. <
  16. Hello from behind Envoy (service 1)! hostname: f26027f1ce28 resolvedhostname: 172.19.0.6
  17. * Connection #0 to host 192.168.99.100 left intact

Step 3: View the traces in Jaeger UI

Point your browser to http://localhost:16686 . You should see the Jaeger dashboard. Set the service to “front-proxy” and hit ‘Find Traces’. You should see traces from the front-proxy. Click on a trace to explore the path taken by the request from front-proxy to service1 to service2, as well as the latency incurred at each hop.