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OpenTelemetry

In order to make a system observable, it must be instrumented. Language specific implementation of OpenTelemetry provides a way to instrument your application without touching your source code. In this lab we're going to instrument a Java application.

Prerequisites​

For this lab it is required to:

  • Enable Tempo
  • Enable Otel
  • Enable Loki
  • Enable Grafana
  • Enable tracing for Istio and Nginx Ingress

Build an image from source code​

For this lab we're going to use the Spring PetClinic Sample Application. Follow these steps to build an image from source code:

note

Using a Gitea repository is not required. You can also build using public repositories.

  1. Create a new repo called petclinic
  2. Clone the Spring PetClinic Sample Application:
git clone https://github.com/spring-projects/spring-petclinic.git
cd spring-petclinic
  1. Mirror the Spring PetClinic Sample Application to your petclinc repo:
git push --mirror https://gitea.<your-domain>/<your-user-name>/petclinic.git
  1. Go to Builds in the left menu and click Create Build
  2. Fill in the Build name petclinic
  3. Choose Buildpacks
  4. Fill in the Repo URL with the petclinic Gitea repo you created
  5. Click Submit

Create a workload from the developer catalog​

Go to the list of Builds and add the repository of the petclinc build to your clipboard. Remember that the tag is latest.

  1. Go to Workloads in the left menu and click on Create Workload
  2. Select k8s-deployment-otel from the catalog
  3. Add the Name petclinic for the workload
  4. Leave the Auto image updater to Disabled
  5. In the workload values, change the following parameters:
image:
  repository: <paste from clipboard>
  tag: latest

Because we're deploying a Java application here, maybe also change the resources:

resources:
  limits:
    cpu: 500m
    memory: 1Gi
  requests:
    cpu: 300m
    memory: 256Mi
  1. Click Submit

Now click on Deploy Changes

Expose the service​

  • In the left menu panel under click Services then click on Create Service
  • Select the petclinic service
  • Under Exposure Ingress, select Ingress and use the default configuration
  • Click Submit
  • Click Deploy Changes

See traces​

To be able to see traces, we'll first need to generate some requests. Click on the URL of the petclinic service and generate some requests.

To see traces, you'll first need to find a TraceID of a trace. Go to Apps in the left menu and then click op Loki. Select the label App and select value petclinic.

Click on a log entry of a request. Note that the requests are logged by the Istio Envoy proxy. You will now see a link to the full trace in Grafana Tempo. Click on it.

note

If you don't see any traces, check and see if the pod runs the ghcr.io/open-telemetry/opentelemetry-operator/autoinstrumentation-java:1.26.0 container. Sometimes the pod starts before the Instrumentation resource has been created. If this is the case, restart the Pod

Team apps

And when you click on the Node graph, you’ll see the complete flow:

Team apps