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Node.js and OpenTelemetry Manual Instrumentation

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 OpenTelemetry Manual Instrumentation 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. This example includes manual instrumentation and a sample bookstore array that simulates fetching data from a database.

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 with Manual Instrumentation:

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

Follow these instructions to run the quick start:

  1. Copy the .env.template file to .env.
  2. Log into the Tracetest app.
  3. This example is configured to use the OpenTelemetry Tracing Backend. Ensure the environment you will be utilizing to run this example is also configured to use the OpenTelemetry Tracing Backend by clicking on Settings, Tracing Backend, OpenTelemetry, Save.
  4. 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.
  5. Run docker compose up -d.
  6. Run tests from the Tracetest Web UI by accessing the app with the URL http://app:8080/books.

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.

OTEL_EXPORTER_OTLP_TRACES_ENDPOINT="http://tracetest-agent:4317/"
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 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",
"availability-with-grpc-tracer": "node -r ./tracing.otel.grpc.js availability.js",
},

Running the Node.js App

To start the full setup, run the following command:

docker compose up -d

Run Tracetest Tests

  1. Open Tracetest
  2. Start creating tests! Make sure to use the http://app:8080/ URL in your test creation.
  3. 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

Here's a sample of a failed test run, which happens if you use this selector and assertion pair.

Selector:

span[tracetest.span.type="general" name="Books List"]

Assertion:

attr: books.list.count = 4

assertion

It fails because books.length is equal to 3.

Learn More

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