Tracing requests | Serverless applications | OpenShift Container Platform 4.4

Configuring Jaeger for use with OpenShift Serverless

Using Jaeger with OpenShift Serverless allows you to enable distributed tracing for your serverless applications on OpenShift Container Platform.

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.

Developers can visualize call flows in large architectures with distributed tracing. which is useful for understanding serialization, parallelism, and sources of latency.

For more information about Jaeger, see Jaeger architecture and Installing Jaeger.

Configuring Jaeger for use with OpenShift Serverless

Prerequisites

Cluster administrator permissions on an OpenShift Container Platform cluster.
You have installed the OpenShift Serverless Operator and Knative Serving.
You have installed the Jaeger Operator.

Procedure

Create and apply a Jaeger custom resource YAML file that contains the following sample YAML:
```
apiVersion: jaegertracing.io/v1
kind: Jaeger
metadata:
  name: jaeger
  namespace: default
```

Enable tracing for Knative Serving by editing the KnativeServing custom resource definition (CRD) and adding a YAML configuration for tracing:

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 will be 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 custom resource 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 steps

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

Get the hostname of the jaeger route:

$ oc get route jaeger

Example output

NAME     HOST/PORT                         PATH   SERVICES       PORT    TERMINATION   WILDCARD
jaeger   jaeger-default.apps.example.com          jaeger-query   <all>   reencrypt     None

Open the endpoint address in your browser to view the console.

Tracing requests using Jaeger

Configuring Jaeger for use with OpenShift Serverless