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Running Tracetest without a Trace Data Store

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.

Sample Node.js app with OpenTelemetry Collector 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.

Prerequisites

You will need Docker and Docker Compose installed on your machine to run this quick start app!

Project Structure

The project is built with Docker Compose. It contains two distinct docker-compose.yaml files.

1. Node.js App

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

2. Tracetest

The docker-compose.yaml file, collector.config.yaml, tracetest-provision.yaml, and tracetest.config.yaml in the tracetest directory are for the setting up Tracetest and the OpenTelemetry Collector.

The tracetest directory is self-contained and will run all the prerequisites for enabling OpenTelemetry traces and trace-based testing with Tracetest.

Docker Compose Network

All services in the docker-compose.yaml are on the same network and will be reachable by hostname from within other services. E.g. tracetest:4317 in the collector.config.yaml will map to the tracetest service, where the port 4317 is the port where Tracetest accepts traces.

Node.js App

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

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

Here's the content of the tracing.otel.grpc.js file:

const opentelemetry = require('@opentelemetry/sdk-node')
const { getNodeAutoInstrumentations } = require('@opentelemetry/auto-instrumentations-node')
const { OTLPTraceExporter } = require('@opentelemetry/exporter-trace-otlp-grpc');

const sdk = new opentelemetry.NodeSDK({
traceExporter: new OTLPTraceExporter({ url: 'http://otel-collector:4317' }),
instrumentations: [getNodeAutoInstrumentations()],
})
sdk.start()

Depending on which of these you choose, traces will be sent to either the grpc or http endpoint.

The hostnames and ports for these are:

  • GRPC: http://otel-collector:4317
  • HTTP: http://otel-collector:4318/v1/traces

Enabling the tracer is done by preloading the trace file.

node -r ./tracing.otel.grpc.js app.js

In the package.json you will see two npm scripts for running the respective tracers alongside the app.js.

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

To start the server, run this command:

npm run with-grpc-tracer
# or
npm run with-http-tracer

As you can see, the Dockerfile uses the command above.

FROM node:slim
WORKDIR /usr/src/app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 8080
CMD [ "npm", "run", "with-grpc-tracer" ]

And, the docker-compose.yaml contains just one service for the Node.js app.

version: '3'
services:
app:
image: quick-start-nodejs
build: .
ports:
- "8080:8080"

To start it, run this command:

docker compose build # optional if you haven't already built the image
docker compose up

This will start the Node.js app. But, you're not sending the traces anywhere.

Let's fix this by configuring Tracetest and OpenTelemetry Collector.

Tracetest

The docker-compose.yaml in the tracetest directory is configured with three services.

  • Postgres - Postgres is a prerequisite for Tracetest to work. It stores trace data when running the trace-based tests.
  • OpenTelemetry Collector - A vendor-agnostic implementation of how to receive, process and export telemetry data.
  • Tracetest - Trace-based testing that generates end-to-end tests automatically from traces.
version: "3"
services:
tracetest:
image: kubeshop/tracetest:latest
platform: linux/amd64
volumes:
- type: bind
source: ./tracetest/tracetest-config.yaml
target: /app/tracetest.yaml
- type: bind
source: ./tracetest/tracetest-provision.yaml
target: /app/provisioning.yaml
ports:
- 11633:11633
command: --provisioning-file /app/provisioning.yaml
depends_on:
postgres:
condition: service_healthy
otel-collector:
condition: service_started
healthcheck:
test: ["CMD", "wget", "--spider", "localhost:11633"]
interval: 1s
timeout: 3s
retries: 60
environment:
TRACETEST_DEV: ${TRACETEST_DEV}

postgres:
image: postgres:14
environment:
POSTGRES_PASSWORD: postgres
POSTGRES_USER: postgres
healthcheck:
test: pg_isready -U "$$POSTGRES_USER" -d "$$POSTGRES_DB"
interval: 1s
timeout: 5s
retries: 60

otel-collector:
image: otel/opentelemetry-collector-contrib:0.59.0
command:
- "--config"
- "/otel-local-config.yaml"
volumes:
- ./tracetest/collector.config.yaml:/otel-local-config.yaml

Tracetest depends on both Postgres and the OpenTelemetry Collector. Both Tracetest and the OpenTelemetry Collector require config files to be loaded via a volume. The volumes are mapped from the root directory into the tracetest directory and the respective config files.

To start both the Node.js app and Tracetest we will run this command:

docker-compose -f docker-compose.yaml -f tracetest/docker-compose.yaml up # add --build if the images are not built already

The tracetest-config.yaml file contains the basic setup of connecting Tracetest to the Postgres instance.

postgres:
host: postgres
user: postgres
password: postgres
port: 5432
dbname: postgres
params: sslmode=disable

The tracetest-provision.yaml file provisions the trace data store and polling to store in the Postgres database. The data store is set to OTLP, meaning the traces will be stored in Tracetest itself.

But how are traces sent to Tracetest?

The collector.config.yaml explains that. It receives traces via either grpc or http. Then, exports them to Tracetest's OLTP endpoint tracetest:4317.

receivers:
otlp:
protocols:
grpc:
http:

processors:
batch:
timeout: 100ms

exporters:
logging:
loglevel: debug
otlp/1:
endpoint: tracetest:4317
# Send traces to Tracetest.
# Read more in docs here: https://docs.tracetest.io/configuration/connecting-to-data-stores/opentelemetry-collector
tls:
insecure: true

service:
pipelines:
traces/1:
receivers: [otlp]
processors: [batch]
exporters: [otlp/1]

Run Both the Node.js App and Tracetest

To start both the Node.js app and Tracetest, run this command:

docker-compose -f docker-compose.yaml -f tracetest/docker-compose.yaml up # add --build if the images are not built already

This will start your Tracetest instance on http://localhost:11633/.

Open the URL and start creating tests! Make sure to use the http://app:8080/ URL in your test creation, because your Node.js app and Tracetest are in the same network.

Learn More

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