chore: update prometheus examples (#2939)

.github/workflows/unit-test.yml

@@ -33,7 +33,7 @@ jobs:
             packages/*/package-lock.json
             experimental/packages/*/node_modules
             experimental/packages/*/package-lock.json
-          key: node-tests-${{ runner.os }}-${{ matrix.node_version }}-${{ hashFiles('package.json', 'packages/*/package.json', 'experimental/packages/*/package.json') }}-04142022
+          key: node-tests-${{ runner.os }}-${{ matrix.node_version }}-${{ hashFiles('package.json', 'packages/*/package.json', 'experimental/packages/*/package.json') }}-04292022
 
       - name: Bootstrap
         run: |
@@ -72,7 +72,7 @@ jobs:
             packages/*/package-lock.json
             experimental/packages/*/node_modules
             experimental/packages/*/package-lock.json
-          key: browser-tests-${{ runner.os }}-${{ hashFiles('package.json', 'packages/*/package.json', 'experimental/packages/*/package.json') }}-04142022
+          key: browser-tests-${{ runner.os }}-${{ hashFiles('package.json', 'packages/*/package.json', 'experimental/packages/*/package.json') }}-04292022
 
       - name: Bootstrap
         run: |
@@ -112,7 +112,7 @@ jobs:
             packages/*/package-lock.json
             experimental/packages/*/node_modules
             experimental/packages/*/package-lock.json
-          key: webworker-tests-${{ runner.os }}-${{ hashFiles('package.json', 'packages/*/package.json', 'experimental/packages/*/package.json') }}-04142022
+          key: webworker-tests-${{ runner.os }}-${{ hashFiles('package.json', 'packages/*/package.json', 'experimental/packages/*/package.json') }}-04292022
 
       - name: Bootstrap
         run: |

experimental/examples/.eslintrc.js

@@ -0,0 +1,7 @@
+module.exports = {
+  "env": {
+      "mocha": true,
+      "node": true
+  },
+  ...require('../../eslint.config.js')
+}

experimental/examples/prometheus/index.js

@@ -0,0 +1,38 @@
+'use strict';
+
+const { DiagConsoleLogger, DiagLogLevel, diag } = require('@opentelemetry/api');
+const { MeterProvider } = require('@opentelemetry/sdk-metrics-base');
+const { PrometheusExporter } = require('@opentelemetry/exporter-prometheus');
+
+// Optional and only needed to see the internal diagnostic logging (during development)
+diag.setLogger(new DiagConsoleLogger(), DiagLogLevel.DEBUG);
+
+const { endpoint, port } = PrometheusExporter.DEFAULT_OPTIONS;
+
+const exporter = new PrometheusExporter({}, () => {
+  console.log(
+    `prometheus scrape endpoint: http://localhost:${port}${endpoint}`,
+  );
+});
+
+// Creates MeterProvider and installs the exporter as a MetricReader
+const meterProvider = new MeterProvider();
+meterProvider.addMetricReader(exporter);
+const meter = meterProvider.getMeter('example-prometheus');
+
+// Creates metric instruments
+const requestCounter = meter.createCounter('requests', {
+  description: 'Example of a Counter',
+});
+
+const upDownCounter = meter.createUpDownCounter('test_up_down_counter', {
+  description: 'Example of a UpDownCounter',
+});
+
+const attributes = { pid: process.pid, environment: 'staging' };
+
+// Record metrics
+setInterval(() => {
+  requestCounter.add(1, attributes);
+  upDownCounter.add(Math.random() > 0.5 ? 1 : -1, attributes);
+}, 1000);

examples/prometheus/package.json → experimental/examples/prometheus/package.json

@@ -1,6 +1,6 @@
 {
   "name": "prometheus-example",
-  "version": "0.25.0",
+  "version": "0.28.0",
   "description": "Example of using @opentelemetry/sdk-metrics-base and  @opentelemetry/exporter-prometheus",
   "main": "index.js",
   "scripts": {
@@ -10,7 +10,7 @@
   "license": "Apache-2.0",
   "dependencies": {
     "@opentelemetry/api": "^1.0.2",
-    "@opentelemetry/exporter-prometheus": "0.25.0",
-    "@opentelemetry/sdk-metrics-base": "0.25.0"
+    "@opentelemetry/exporter-prometheus": "0.28.0",
+    "@opentelemetry/sdk-metrics-base": "0.28.0"
   }
 }