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Distributed tracing records the path of a request through the various services that make up an application. It is used to tie information about different units of work together, to understand a whole chain of events in a distributed transaction. The units of work might be executed in different processes or hosts.

Using Jaeger to enable distributed tracing

If you do not want to install all of the components of Red Hat OpenShift distributed tracing, you can still use distributed tracing on OpenShift Dedicated with OpenShift Serverless. To do this, you must install and configure Jaeger as a standalone integration.

Prerequisites
  • You have access to an OpenShift Dedicated account with cluster or dedicated administrator access.

  • You have installed the OpenShift Serverless Operator and Knative Serving.

  • You have installed the Red Hat OpenShift distributed tracing platform Operator.

  • You have installed the OpenShift (oc) CLI.

  • You have created a project or have access to a project with the appropriate roles and permissions to create applications and other workloads in OpenShift Dedicated.

Procedure
  1. Create and apply a Jaeger custom resource (CR) that contains the following:

    Jaeger CR
    apiVersion: jaegertracing.io/v1
    kind: Jaeger
    metadata:
      name: jaeger
      namespace: default
  2. Enable tracing for Knative Serving, by editing the KnativeServing CR and adding a YAML configuration for tracing:

    Tracing YAML example
    apiVersion: operator.knative.dev/v1alpha1
    kind: KnativeServing
    metadata:
      name: knative-serving
      namespace: knative-serving
    spec:
      config:
        tracing:
          sample-rate: "0.1" (1)
          backend: zipkin (2)
          zipkin-endpoint: "http://jaeger-collector.default.svc.cluster.local:9411/api/v2/spans" (3)
          debug: "false" (4)
    1 The sample-rate defines sampling probability. Using sample-rate: "0.1" means that 1 in 10 traces are sampled.
    2 backend must be set to zipkin.
    3 The zipkin-endpoint must point to your jaeger-collector service endpoint. To get this endpoint, substitute the namespace where the Jaeger CR is applied.
    4 Debugging should be set to false. Enabling debug mode by setting debug: "true" allows all spans to be sent to the server, bypassing sampling.
Verification

You can access the Jaeger web console to see tracing data, by using the jaeger route.

  1. Get the jaeger route’s hostname by entering the following command:

    $ oc get route jaeger -n default
    Example output
    NAME     HOST/PORT                         PATH   SERVICES       PORT    TERMINATION   WILDCARD
    jaeger   jaeger-default.apps.example.com          jaeger-query   <all>   reencrypt     None
  2. Open the endpoint address in your browser to view the console.