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Node.js and OpenTelemetry

note

Check out the source code on GitHub here.

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.

Node.js App with Tracetest​

This is a 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.

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 Node.js Quickstart:

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

Follow these instructions to run the quick start:

  1. Copy the .env.template file to .env.
  2. Fill out the TRACETEST_TOKEN and ENVIRONMENT_ID details by editing your .env file.
  3. Run docker compose run tracetest-run.
  4. Follow the links in the output to view the test results.

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

Project Structure​

The quick start Node.js project is built with Docker Compose and contains the Tracetest Agent 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.

# Get the required information here: https://app.tracetest.io/retrieve-token

TRACETEST_TOKEN="<YOUR_TRACETEST_TOKEN>"
TRACETEST_ENVIRONMENT_ID="<YOUR_ENV_ID>"

# GRPC
OTEL_EXPORTER_OTLP_TRACES_ENDPOINT="http://tracetest-agent:4317/"
# or, use HTTP
# OTEL_EXPORTER_OTLP_TRACES_ENDPOINT="http://tracetest-agent:4318/v1/traces"

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 Tracetest Agent'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",
},

Running the Node.js App and Tracetest​

To execute the tests, run this command:

docker compose run tracetest-run

This will:

  1. Start the Node.js app, the OpenTelemetry Collector, and send the traces to the Tracetest Agent.
  2. Start the Tracetest Agent.
  3. Configure the tracing backend and create tests in your environment.
  4. Run the tests.

The output of the test will look similar to this:

Configuring Tracetest
 SUCCESS  Successfully configured Tracetest CLI
Running Trace-Based Tests...
✘ RunGroup: #VnMxUljSg (https://app.tracetest.io/organizations/xxx/environments/xxx/run/VnMxUljSg)
 Summary: 0 passed, 1 failed, 0 pending
  ✘ Test API (https://app.tracetest.io/organizations/xxx/environments/xxx/test/W656Q0c4g/run/1/test) - trace id: 9d33bbecf956d66b3b277d12e9ca4d3c
	✘ span[tracetest.span.type="http" name="GET /" http.target="/" http.method="GET"]
		✘ #94880e7cd465bd33
			✔ attr:http.status_code  =  200 (200)
			✘ attr:tracetest.span.duration  <  500ms (1s) (https://app.tracetest.io/organizations/xxx/environments/xxx/test/W656Q0c4g/run/1/test?selectedAssertion=0&selectedSpan=94880e7cd465bd33)

	✘ Required gates
		✘ test-specs

assertion

Learn More​

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