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
andNginx 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:
Using a Gitea repository is not required. You can also build using public repositories.
-
Create a new repo called
petclinic
. -
Clone the Spring PetClinic Sample Application:
git clone https://github.com/spring-projects/spring-petclinic.git
cd spring-petclinic
- Mirror the Spring PetClinic Sample Application to your
petclinc
repo:
git push --mirror https://gitea.<your-domain>/<your-user-name>/petclinic.git
-
Go to
Builds
in the left menu and clickCreate Build
. -
Fill in the Build name
petclinic
. -
Choose
Buildpacks
. -
Fill in the
Repo URL
with thepetclinic
Gitea repo you created. -
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.
-
Go to
Workloads
in the left menu and click onCreate Workload
. -
Select
Quickstart-K8s-Deployment-Otel
from the catalog. -
Add the Name
petclinic
for the workload. -
Leave the
Auto image updater
toDisabled
. -
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
-
Click
Submit
. -
Click on
Deploy Changes
.
Expose the service
-
In the left menu panel under click
Services
then click onCreate Service
. -
Select the
petclinic
service. -
Under
Exposure Ingress
, selectIngress
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.
If you don't see any traces, then 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.
And when you click on the Node graph, you’ll see the complete flow: