opentelemetry

Instrumenting Node.js applications with EDOT SDKs on Kubernetes

This document focuses on instrumenting Node.js applications on Kubernetes, using the OpenTelemetry Operator, the Elastic Distribution of OpenTelemetry (EDOT) Collectors, and the EDOT Node.js SDK.

For general knowledge about the EDOT Node.js SDK, refer to the getting started guide and configuration.
For Node.js auto-instrumentation specifics, refer to OpenTelemetry Operator Node.js auto-instrumentation.
For general information about instrumenting applications on kubernetes, refer to instrumenting applications.

Instrument a Node.js app with EDOT Node.js SDK on Kubernetes

In this example, you’ll learn how to:

Enable auto-instrumentation of a Node.js application using one of the following supported methods:
- Adding an annotation to the deployment Pods.
- Adding an annotation to the namespace.
Verify that auto-instrumentation libraries are injected and configured correctly.
Confirm data is flowing to Kibana Observability.

For this example, we assume the application you’re instrumenting is a deployment named nodejs-app running in the nodejs-ns namespace.

Ensure you have successfully installed the OpenTelemetry Operator, and confirm that the following Instrumentation object exists in the system:
```
 $ kubectl get instrumentation -n opentelemetry-operator-system
 NAME                      AGE    ENDPOINT
 elastic-instrumentation   107s   http://opentelemetry-kube-stack-daemon-collector.opentelemetry-operator-system.svc.cluster.local:4318
```
[!NOTE] If your Instrumentation object has a different name or is created in a different namespace, you will have to adapt the annotation value in the next step.

Enable auto-instrumentation of your Node.js application using one of the following methods:

Edit your application workload definition and include the annotation under spec.template.metadata.annotations:

kind: Deployment
metadata:
  name: nodejs-app
  namespace: nodejs-ns
spec:
...
  template:
    metadata:
...
      annotations:
        instrumentation.opentelemetry.io/inject-nodejs: opentelemetry-operator-system/elastic-instrumentation
...

Alternatively, add the annotation at namespace level to apply auto-instrumentation in all Pods of the namespace:

kubectl annotate namespace nodejs-ns instrumentation.opentelemetry.io/inject-nodejs=opentelemetry-operator-system/elastic-instrumentation

Restart application

Once the annotation has been set, restart the application to create new Pods and inject the instrumentation libraries:
```
   kubectl rollout restart deployment nodejs-app -n nodejs-ns
```

Verify the auto-instrumentation resources are injected in the Pods:

Run a kubectl describe of one of your application Pods and check:

There should be an init container named opentelemetry-auto-instrumentation-nodejs in the Pod. For example:

$ kubectl describe pod nodejs-app-8d84c47b8-8h5z2 -n nodejs-ns
Name:             nodejs-app-8d84c47b8-8h5z2
Namespace:        nodejs-ns
...
...
Init Containers:
  opentelemetry-auto-instrumentation-nodejs:
    Container ID:  containerd://cbf67d7ca1bd62c25614b905a11e81405bed6fd215f2df21f84b90fd0279230b
    Image:         docker.elastic.co/observability/elastic-otel-node:0.5.0
    Command:
      cp
      -r
      /autoinstrumentation/.
      /otel-auto-instrumentation-nodejs
    State:          Terminated
      Reason:       Completed
      Exit Code:    0
      Started:      Wed, 13 Nov 2024 15:47:02 +0100
      Finished:     Wed, 13 Nov 2024 15:47:03 +0100
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /otel-auto-instrumentation-nodejs from opentelemetry-auto-instrumentation-nodejs (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-swhn5 (ro)

The main container of the deployment loads the SDK through the NODE_OPTIONS environment variable:

...
Containers:
  nodejs-app:
    Environment:
...
      NODE_OPTIONS:                           --require /otel-auto-instrumentation-nodejs/autoinstrumentation.js
      OTEL_SERVICE_NAME:                     nodejs-app
      OTEL_EXPORTER_OTLP_ENDPOINT:           http://opentelemetry-kube-stack-daemon-collector.opentelemetry-operator-system.svc.cluster.local:4318
...

Ensure the environment variable OTEL_EXPORTER_OTLP_ENDPOINT points to a valid endpoint and there’s network communication between the Pod and the endpoint.

The Pod has an EmptyDir volume named opentelemetry-auto-instrumentation-nodejs mounted in both the main and the init containers in path /otel-auto-instrumentation-nodejs.

Init Containers:
  opentelemetry-auto-instrumentation-nodejs:
...
    Mounts:
      /otel-auto-instrumentation-nodejs from opentelemetry-auto-instrumentation-nodejs (rw)
Containers:
  nodejs-app:
...
    Mounts:
      /otel-auto-instrumentation-nodejs from opentelemetry-auto-instrumentation-nodejs (rw)
...
Volumes:
...
  opentelemetry-auto-instrumentation-nodejs:
    Type:        EmptyDir (a temporary directory that shares a pod's lifetime)

Confirm data is flowing to Kibana:
- Open Observability -> Applications -> Service inventory, and determine if:
  - The application appears in the list of services (nodejs-app in the example).
  - The application shows transactions and metrics.
  [!TIP] You may need to generate traffic to your application to see spans and metrics.
- For application container logs, open Kibana Discover and filter for your Pods’ logs. In the provided example, we could filter for them with either of the following:
  - k8s.deployment.name: "nodejs-app" (adapt the query filter to your use case)
  - k8s.pod.name: nodejs-app* (adapt the query filter to your use case)
Note that the container logs are not provided by the instrumentation library, but by the DaemonSet collector deployed as part of the operator installation.

Troubleshooting

Refer to troubleshoot auto-instrumentation for further analysis.