// Module is included in the following assemblies:
//
// * serverless/serverless-tracing.adoc

:_mod-docs-content-type: PROCEDURE
[id="serverless-open-telemetry_{context}"]
= Using {DTProductName} to enable distributed tracing

{DTProductName} is made up of several components that work together to collect, store, and display tracing data.

.Prerequisites

* You have access to an {product-title} account with cluster administrator access.
* You have not yet installed the {ServerlessOperatorName}, Knative Serving, and Knative Eventing. These must be installed after the {DTProductName} installation.
* You have installed {DTProductName} by following the {product-title} "Installing distributed tracing" documentation.
* You have installed the OpenShift CLI (`oc`).
* You have created a project or have access to a project with the appropriate roles and permissions to create applications and other workloads in {product-title}.

.Procedure

. Create an `OpenTelemetryCollector` custom resource (CR):
+
.Example OpenTelemetryCollector CR
[source,yaml]
----
apiVersion: opentelemetry.io/v1alpha1
kind: OpenTelemetryCollector
metadata:
  name: cluster-collector
  namespace: <namespace>
spec:
  mode: deployment
  config: |
    receivers:
      zipkin:
    processors:
    exporters:
      jaeger:
        endpoint: jaeger-all-in-one-inmemory-collector-headless.tracing-system.svc:14250
        tls:
          ca_file: "/var/run/secrets/kubernetes.io/serviceaccount/service-ca.crt"
      logging:
    service:
      pipelines:
        traces:
          receivers: [zipkin]
          processors: []
          exporters: [jaeger, logging]
----

. Verify that you have two pods running in the namespace where {DTProductName} is installed:
+
[source,terminal]
----
$ oc get pods -n <namespace>
----
+
.Example output
[source,terminal]
----
NAME                                          READY   STATUS    RESTARTS   AGE
cluster-collector-collector-85c766b5c-b5g99   1/1     Running   0          5m56s
jaeger-all-in-one-inmemory-ccbc9df4b-ndkl5    2/2     Running   0          15m
----

. Verify that the following headless services have been created:
+
[source,terminal]
----
$ oc get svc -n <namespace> | grep headless
----
+
.Example output
[source,terminal]
----
cluster-collector-collector-headless            ClusterIP   None             <none>        9411/TCP                                 7m28s
jaeger-all-in-one-inmemory-collector-headless   ClusterIP   None             <none>        9411/TCP,14250/TCP,14267/TCP,14268/TCP   16m
----
+
These services are used to configure Jaeger, Knative Serving, and Knative Eventing. The name of the Jaeger service may vary.

. Install the {ServerlessOperatorName} by following the "Installing the {ServerlessOperatorName}" documentation.

. Install Knative Serving by creating the following `KnativeServing` CR:
+
.Example KnativeServing CR
[source,yaml]
----
apiVersion: operator.knative.dev/v1beta1
kind: KnativeServing
metadata:
    name: knative-serving
    namespace: knative-serving
spec:
  config:
    tracing:
      backend: "zipkin"
      zipkin-endpoint: "http://cluster-collector-collector-headless.tracing-system.svc:9411/api/v2/spans"
      debug: "false"
      sample-rate: "0.1" <1>
----
<1> The `sample-rate` defines sampling probability. Using `sample-rate: "0.1"` means that 1 in 10 traces are sampled.

. Install Knative Eventing by creating the following `KnativeEventing` CR:
+
.Example KnativeEventing CR
[source,yaml]
----
apiVersion: operator.knative.dev/v1beta1
kind: KnativeEventing
metadata:
    name: knative-eventing
    namespace: knative-eventing
spec:
  config:
    tracing:
      backend: "zipkin"
      zipkin-endpoint: "http://cluster-collector-collector-headless.tracing-system.svc:9411/api/v2/spans"
      debug: "false"
      sample-rate: "0.1" <1>
----
<1> The `sample-rate` defines sampling probability. Using `sample-rate: "0.1"` means that 1 in 10 traces are sampled.

. Create a Knative service:
+
.Example service
[source,yaml]
----
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: helloworld-go
spec:
  template:
    metadata:
      labels:
        app: helloworld-go
      annotations:
        autoscaling.knative.dev/minScale: "1"
        autoscaling.knative.dev/target: "1"
    spec:
      containers:
      - image: quay.io/openshift-knative/helloworld:v1.2
        imagePullPolicy: Always
        resources:
          requests:
            cpu: "200m"
        env:
        - name: TARGET
          value: "Go Sample v1"
----

. Make some requests to the service:
+
.Example HTTPS request
[source,terminal]
----
$ curl https://helloworld-go.example.com
----

. Get the URL for the Jaeger web console:
+
.Example command
[source,terminal]
----
$ oc get route jaeger-all-in-one-inmemory  -o jsonpath='{.spec.host}' -n <namespace>
----
+
You can now examine traces by using the Jaeger console.