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Node.js and Jaeger

Tracetest is a testing tool based on OpenTelemetry that allows you to test your distributed application. It allows you to use data from distributed traces generated by OpenTelemetry to validate and assert if your application has the desired behavior defined by your test definitions.

Jaeger is an open-source, end-to-end distributed tracing solution. It allows you to monitor and troubleshoot transactions in complex distributed systems. It was developed and then open sourced by Uber Technologies. Jaeger provides a distributed tracing solution to enable transactions across multiple heterogeneous systems or microservices to be tracked and displayed as a cascading series of spans.

Node.js App with Jaeger, OpenTelemetry and Tracetest

This is a simple quick start on how to configure a Node.js app to use OpenTelemetry instrumentation with traces and Tracetest for enhancing your E2E and integration tests with trace-based testing. The infrastructure will use Jaeger as the trace data store, and OpenTelemetry Collector to receive traces from the Node.js app and send them to Jaeger.

Prerequisites

Tracetest Account:

Docker: Have Docker and Docker Compose installed on your machine.

Run This Quckstart Example

The example below is provided as part of the Tracetest project. You can download and run the example by following these steps:

Clone the Tracetest project and go to the Jaeger Node.js Quickstart:

git clone https://github.com/kubeshop/tracetest
cd tracetest/examples/quick-start-jaeger-nodejs

Follow these instructions to run the quick start:

  1. Copy the .env.template file to .env.
  2. Log into the Tracetest app.
  3. Fill out the token and API key details by editing your .env file. You can find these values in the Settings area for your environment.
  4. Run docker compose -f ./docker-compose.yaml -f ./docker-compose.agent.yaml up -d.
  5. This example is configured to use the Jaeger Tracing Backend. Ensure the environment you're using to run this example is configured to use the Jaeger Tracing Backend by clicking on Settings, Tracing Backend, Jaeger, Save. Or, use the CLI as explained below.
  6. Run tests from the Tracetest Web UI by accessing the app with the URL http://app:8080/.

Follow along with the sections below for an in detail breakdown of what the example you just ran did and how it works.

Project Structure

The project contains Tracetest Agent, OpenTelemetry Collector, and a Node.js app.

The docker-compose.yaml file in the root directory of the quick start runs the Node.js app and the Tracetest Agent setup.

Configuring the Node.js App

The Node.js app is a simple Express app, contained in the app.js file.

Configure the .env like shown below.

TRACETEST_API_KEY="<YOUR_TRACETEST_API_KEY>"

The OpenTelemetry tracing is contained in the tracing.otel.grpc.js or tracing.otel.http.js files. Traces will be sent to Tracetest Agent.

Choosing the tracing.otel.grpc.js file will send traces to OpenTelemetry Collector's GRPC endpoint.

Enabling the tracer is done by preloading the trace file. As seen in the package.json.

"scripts": {
"app-with-grpc-tracer": "node -r ./tracing.otel.grpc.js app.js",
},

Configuring Jaeger

Configure Jaeger as a Tracing Backend:

---
type: DataStore
spec:
name: Jaeger
type: jaeger
default: true
jaeger:
endpoint: jaeger:16685
tls:
insecure: true
tracetest config -t <YOUR_API_TOKEN>
tracetest apply datastore -f ./tracetest-tracing-backend.yaml

Run the Node.js App, Jaeger and OpenTelemetry Collector with Docker Compose

The docker-compose.yaml file and Dockerfile in the root directory are for the Node.js app. The docker-compose.yaml contains one service for the Node.js app.

The docker-compose.agent.yaml file is for the Tracetest Agent, Jaeger, and OpenTelemetry Collector.

The collector.config.yaml configures the OpenTelemetry Collector. It receives traces via either grpc or http. Then, exports them to Jaeger via the OTLP exporter.

To start it, run this command:

docker compose -f ./docker-compose.yaml -f ./docker-compose.agent.yaml up -d

This will start the Node.js app the OpenTelemetry Collector and send the traces to Jaeger.

Run Tracetest Tests

  1. Open Tracetest
  2. Configure Jaeger as a tracing backend if you have not already as explained above.
  3. Start creating tests! Make sure to use the http://app:8080/ URL in your test creation.
  4. To trigger tests in the CLI, first install the CLI, configure it, and run a test. From the root of the quick start directory, run:
tracetest configure -t <YOUR_API_TOKEN>
tracetest run test -f ./test-api.yaml

Learn More

Feel free to check out our examples in GitHub and join our Slack Community for more info!