echo server for testing

echo.js

@@ -0,0 +1,23 @@
+'use strict'
+
+let count = 0
+const port = process.env.PORT || 5555
+const net = require('net')
+const server = net.createServer((socket) => {
+  socket.on('data', (chunk) => {
+    console.log(`${++count} ` + chunk)
+  })
+})
+
+process.once('SIGINT', onSignal)
+process.once('SIGTERM', onSignal)
+server.listen(port, (err) => {
+  if (err) {
+    console.log(err)
+    process.exitCode = 1
+  }
+  console.log('server listening')
+})
+function onSignal() {
+  server.close()
+}