examples(lgtm): add code sample for blog post

examples/lgtm-end-to-end-observability-testing/.dockerignore

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+node_modules
+docker-compose
+tempo-data
+grafana

examples/lgtm-end-to-end-observability-testing/.env.sample

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+# Get the required information here: https://app.tracetest.io/retrieve-token
+
+TRACETEST_TOKEN=
+TRACETEST_ENVIRONMENT_ID=
+
+OTEL_EXPORTER_OTLP_TRACES_ENDPOINT="http://tempo:4318/v1/traces"

examples/lgtm-end-to-end-observability-testing/.gitignore

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+.env
+node_modules
+tempo-data

examples/lgtm-end-to-end-observability-testing/Dockerfile

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+FROM node:slim
+WORKDIR /usr/src/app/
+COPY package*.json ./
+RUN npm install
+COPY . .
+EXPOSE 8081

examples/lgtm-end-to-end-observability-testing/docker-compose.yml

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+version: '3.8'
+
+services:
+  app:
+    image: adnanrahic/tracetest-app
+    build: .
+    command: npm run index-with-tracer
+    ports:
+      - "8081:8081"
+    environment:
+      - OTEL_EXPORTER_OTLP_TRACES_ENDPOINT=${OTEL_EXPORTER_OTLP_TRACES_ENDPOINT}
+    depends_on:
+      tempo:
+        condition: service_started
+      tracetest-agent:
+        condition: service_started
+
+  prometheus:
+    image: prom/prometheus
+    volumes:
+      - ./prometheus.yml:/etc/prometheus/prometheus.yml
+    ports:
+      - "9090:9090"
+
+  loki:
+    image: grafana/loki:2.9.10
+    ports:
+      - "3100:3100"
+    environment:
+      - LOKI_ENABLE_API=true
+
+  init:
+    image: &tempoImage grafana/tempo:latest
+    user: root
+    entrypoint:
+      - "chown"
+      - "10001:10001"
+      - "/var/tempo"
+    volumes:
+      - ./tempo-data:/var/tempo
+
+  tempo:
+    image: *tempoImage
+    command: [ "-config.file=/etc/tempo.yaml" ]
+    volumes:
+      - ./tempo.yaml:/etc/tempo.yaml
+      - ./tempo-data:/var/tempo
+    ports:
+      - "3200:80"   # tempo http
+      - "9095:9095" # tempo grpc
+    depends_on:
+      - init
+
+  tracetest-agent:
+    image: kubeshop/tracetest-agent:v1.7.1
+    environment:
+      - TRACETEST_API_KEY=${TRACETEST_TOKEN}
+      - TRACETEST_ENVIRONMENT_ID=${TRACETEST_ENVIRONMENT_ID}
+
+  grafana:
+    image: grafana/grafana:latest
+    ports:
+      - "3000:3000"
+    environment:
+      - GF_SECURITY_ADMIN_PASSWORD=admin
+    volumes:
+      - ./grafana:/var/lib/grafana
+

examples/lgtm-end-to-end-observability-testing/index.js

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+const express = require('express');
+const logger = require('./logger');
+const meter = require('./meter');
+// const tracer = require('./tracer');
+
+// Create an Express app
+const app = express();
+
+// Define a custom metric (e.g., a request counter)
+const requestCounter = meter.createCounter('http_requests', {
+  description: 'Counts HTTP requests',
+});
+
+// Middleware to increment the counter on every request
+app.use((req, res, next) => {
+  // Increment the request counter
+  logger.info(`Received request for ${req.url}`);
+  requestCounter.add(1, { method: req.method, route: req.path });
+  next();
+});
+
+// Define a simple route
+app.get('/', (req, res) => {
+  // const span = tracer.startSpan('handle_root_request');
+
+  // Simulate some work
+  setTimeout(() => {
+    res.send('Hello, World!');
+    // span.end();
+  }, 100);
+});
+
+// Start the server
+app.listen(8081, () => {
+  logger.info('Server is running on http://localhost:5000');
+  console.log('Server is running on http://localhost:5000');
+});

examples/lgtm-end-to-end-observability-testing/logger.js

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+// logger.js
+const winston = require('winston');
+const LokiTransport = require('winston-loki');
+
+// Configure Winston to send logs to Loki
+const logger = winston.createLogger({
+  level: 'info',
+  format: winston.format.json(),
+  transports: [
+    new LokiTransport({
+      host: 'http://loki:3100', // Assuming Loki is accessible at this URL
+      labels: { job: 'loki-service' },
+      json: true,
+      batching: true,
+      interval: 5, // Send logs in batches every 5 seconds
+    }),
+  ],
+});
+
+module.exports = logger;
+

examples/lgtm-end-to-end-observability-testing/meter.js

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+const { MeterProvider } = require('@opentelemetry/sdk-metrics');
+const { PrometheusExporter } = require('@opentelemetry/exporter-prometheus');
+const { Resource } = require('@opentelemetry/resources');
+const { SemanticResourceAttributes } = require('@opentelemetry/semantic-conventions');
+
+// Prometheus Exporter for metrics
+const prometheusExporter = new PrometheusExporter({
+  port: 9464,             // Port where metrics will be exposed
+  endpoint: '/metrics',    // Endpoint for Prometheus to scrape
+}, () => {
+  console.log('Prometheus scrape endpoint: http://localhost:9464/metrics');
+});
+
+// MeterProvider for manual metrics instrumentation
+const meterProvider = new MeterProvider({
+  resource: new Resource({
+    [SemanticResourceAttributes.SERVICE_NAME]: 'hello-world-app',  // Use semantic attributes for service name
+  }),
+});
+
+// Bind the PrometheusExporter as a MetricReader to the MeterProvider
+meterProvider.addMetricReader(prometheusExporter);
+
+// Create a meter from the meterProvider
+const meter = meterProvider.getMeter('hello-world-meter');
+
+module.exports = meter;
+
+
+