Add Zipkin trace capturing with output to JSON.

bench/capture-trace.js

@@ -0,0 +1,66 @@
+const http = require('http')
+const fs = require('fs')
+
+const PORT = 9411
+const HOST = '0.0.0.0'
+
+const traces = []
+
+const onReady = () => console.log(`Listening on http://${HOST}:${PORT}`)
+const onRequest = async (req, res) => {
+  if (
+    req.method !== 'POST' ||
+    req.url !== '/api/v2/spans' ||
+    (req.headers && req.headers['content-type']) !== 'application/json'
+  ) {
+    res.writeHead(200)
+    return res.end()
+  }
+
+  try {
+    const body = JSON.parse(await getBody(req))
+    for (const traceEvent of body) {
+      traces.push(traceEvent)
+    }
+    res.writeHead(200)
+  } catch (err) {
+    console.warn(err)
+    res.writeHead(500)
+  }
+
+  res.end()
+}
+
+const getBody = (req) =>
+  new Promise((resolve, reject) => {
+    let data = ''
+    req.on('data', (chunk) => {
+      data += chunk
+    })
+    req.on('end', () => {
+      if (!req.complete) {
+        return reject('Connection terminated before body was received.')
+      }
+      resolve(data)
+    })
+    req.on('aborted', () => reject('Connection aborted.'))
+    req.on('error', () => reject('Connection error.'))
+  })
+
+const main = () => {
+  const args = process.argv.slice(2)
+  const outFile = args[0] || `./trace-${Date.now()}.json`
+
+  process.on('SIGINT', () => {
+    console.log(`\nSaving to ${outFile}...`)
+    fs.writeFileSync(outFile, JSON.stringify(traces, null, 2))
+    process.exit()
+  })
+
+  const server = http.createServer(onRequest)
+  server.listen(PORT, HOST, onReady)
+}
+
+if (require.main === module) {
+  main()
+}