[Feat] add code with example config files for Cloudflare worker

.env.example

@@ -0,0 +1,5 @@
+INFLUXDB_HOST=http://localhost
+INFLUXDB_DATABASE=example
+INFLUXDB_METRIC=views
+INFLUXDB_USERNAME=admin
+INFLUXDB_PASSWORD=pass

.gitignore

@@ -8,3 +8,5 @@ wasm-pack.log
 worker/
 node_modules/
 .cargo-ok
+.env
+wrangler.toml

index.js

@@ -1,12 +1,102 @@
+// settings
+const MAX_REQUESTS_PER_BATCH = process.env.MAX_REQUESTS_PER_BATCH || 150;
+const MAX_TIME_AWAIT_PER_BATCH = process.env.MAX_TIME_AWAIT_PER_BATCH || 10 * 1000;
+
+const INFLUXDB_HOST = process.env.INFLUXDB_HOST;
+const INFLUXDB_DATABASE = process.env.INFLUXDB_DATABASE;
+const INFLUXDB_METRIC = process.env.INFLUXDB_METRIC;
+const INFLUXDB_USERNAME = process.env.INFLUXDB_USERNAME;
+const INFLUXDB_PASSWORD = process.env.INFLUXDB_PASSWORD;
+const INFLUXDB_URL = `${INFLUXDB_HOST}/write?db=${INFLUXDB_DATABASE}&precision=s&u=${INFLUXDB_USERNAME}&p=${INFLUXDB_PASSWORD}`;
+
+// global vars
+let requests = [];
+let batchIsRunning = false;
+
 addEventListener('fetch', event => {
-  event.respondWith(handleRequest(event.request))
+  event.passThroughOnException();
+  event.respondWith(logRequests(event));
 })
-/**
- * Respond with hello worker text
- * @param {Request} request
- */
-async function handleRequest(request) {
-  return new Response('Hello worker!', {
-    headers: { 'content-type': 'text/plain' },
+
+async function logRequests(event) {
+  let requestStartTime, requestEndTime;
+  if (!batchIsRunning) {
+    event.waitUntil(handleBatch(event));
+  }
+  if (requests.length >= MAX_REQUESTS_PER_BATCH) {
+    event.waitUntil(sendMetricsToInfuxDB())
+  }
+  requestStartTime = Date.now();
+  const response = await fetch(event.request);
+  requestEndTime = Date.now();
+
+  requests.push(getRequestData(event.request, response, requestStartTime, requestEndTime));
+
+  return response;
+}
+
+async function handleBatch(event) {
+  batchIsRunning = true;
+  await sleep(MAX_TIME_AWAIT_PER_BATCH);
+  try {
+    if (requests.length) event.waitUntil(sendMetricsToInfuxDB())
+  } catch (e) {
+    console.error(e);
+  }
+  requests = [];
+  batchIsRunning = false;
+}
+
+function sleep(ms) {
+  return new Promise(resolve => {
+    setTimeout(resolve, ms)
   })
 }
+
+function getRequestData(request, response, startTime, endTime) {
+  const cfData = request.cf || {};
+  const timestamp = Math.floor(Date.now() / 1000);
+  const originResponse = response || {};
+  return {
+    'timestamp': timestamp,
+    'userAgent': request.headers.get('user-agent'),
+    'referer': request.headers.get('Referer'),
+    'ip': request.headers.get('CF-Connecting-IP'),
+    'countryCode': cfData.country,
+    'url': request.url,
+    'method': request.method,
+    'status': originResponse.status,
+    'originTime': (endTime - startTime),
+    'cfCache': (originResponse) ? (response.headers.get('CF-Cache-Status') || 'miss') : 'miss',
+  };
+
+}
+
+function formMetricLine(data) {
+  let referer;
+  const url = new URL(data.url);
+  const utmSource = url.searchParams.get('utm_source') || 'empty';
+  try {
+    referer = new URL(data.referer);
+  } catch {
+    referer = {
+      hostname: 'empty'
+    };
+  }
+  return `${INFLUXDB_METRIC},status_code=${data.status},url=${data.url},hostname=${url.hostname},pathname=${url.pathname},method=${data.method},cf_cache=${data.cfCache},country=${data.countryCode},referer=${referer.hostname},utm_source=${utmSource} duration=${data.originTime} ${data.timestamp}`
+}
+
+async function sendMetricsToInfuxDB() {
+  const metrics = requests.map(formMetricLine).join('\n');
+  console.log("posting", metrics);
+  try {
+    return fetch(INFLUXDB_URL, {
+      method: 'POST',
+      body: metrics,
+    }).then(function (r) {
+      return r;
+    });
+  } catch (err) {
+    console.log(err.stack || err);
+  }
+}