Observability Course Labs

Lab Solution

The traceparent header has quite a complex format, and if you use an invalid ID then it won't get propagated.

There are some example headers in the W3C spec which have valid IDs, so you can use one of those:

curl -H "traceparent: 00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-01" localhost:8070/index?all

You'll see an HTML response containing the document IDs - be sure to use the correct URL so the web app calls into the document API.

Check the logs for the web app:

docker logs obsfun_fulfilment-web_1 -n 22

You'll see a final log like this, which is the server span for the curl call:

Activity.Id:          00-0af7651916cd43dd8448eb211c80319c-6f70aaf42a3e1842-01
Activity.ParentId:    00-0af7651916cd43dd8448eb211c80319c-b7ad6b7169203331-01
Activity.ActivitySourceName: OpenTelemetry.Instrumentation.AspNetCore
Activity.DisplayName: Index
Activity.Kind:        Server
Activity.StartTime:   2021-07-19T16:02:30.7422710Z
Activity.Duration:    00:00:00.0193704
Activity.TagObjects:
    http.host: localhost:8070
    http.method: GET
    http.path: /index
    http.url: http://localhost:8070/index?all
    http.user_agent: curl/7.55.1
    http.route: Index
    http.status_code: 200

The trace ID is shown in the Activity.ParentId field. This is the first call in the chain and because we set a trace ID, the web app uses that as the parent.

The span ID starts with 00-0af7651916cd43dd8448eb211c80319c, which is the trace ID.

Check the API logs:

docker logs obsfun_fulfilment-api_1 -n 1

You'll see a final log entry like this:

2021-07-19 16:02:30.754  INFO 1 --- [p-nio-80-exec-7] i.j.internal.reporters.LoggingReporter   : Span reported: af7651916cd43dd8448eb211c80319c:9ee709025ddee655:2f0d964815ca6846:1 - get

The ID of the span begins with the trace ID we set in the curl header (minus the initial 00- which is the trace format version number).

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