feat: initial commit

.env.example

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+PROBE_PORT=3567

Dockerfile

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+FROM node:20-alpine
+
+WORKDIR /app
+
+COPY probe-server.js /app/probe-server.js
+
+ENV PORT=19090
+ENV HOST=0.0.0.0
+
+EXPOSE 19090
+
+CMD ["node", "probe-server.js"]
+

docker-compose.yml

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+services:
+  probe-server:
+    build:
+      context: .
+    container_name: yc-probe-server
+    restart: always
+    environment:
+      PORT: ${PROBE_PORT:-19090}
+      HOST: 0.0.0.0
+    ports:
+      - "${PROBE_PORT:-19090}:${PROBE_PORT:-19090}"
+

probe-server.js

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+'use strict';
+
+const net = require('node:net');
+
+const PORT = Number(process.env.PORT || 19090);
+const HOST = process.env.HOST || '0.0.0.0';
+
+if (Number.isNaN(PORT)) {
+  throw new Error('PORT must be a number');
+}
+
+const server = net.createServer((socket) => {
+  socket.setKeepAlive(true, 15000);
+
+  socket.on('data', (buf) => {
+    const msg = buf.toString('utf8').trim();
+    if (msg === 'ping') {
+      socket.write('pong\n');
+    }
+  });
+});
+
+server.listen(PORT, HOST, () => {
+  console.log(`[probe] listening on ${HOST}:${PORT}`);
+});
+