Adds --wrap-cmd.

Use --wrap-cmd to tie the server's lifetime to a child process. This is useful as a wrapper to launch apps that depend on the server being accessible. Use --wrap-cwd to set the working directory for the subprocess.
mildmojo · Sep 23, 2017 · d99fb8f · d99fb8f
1 parent b072ffc
commit d99fb8f
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Showing 2 changed files with 73 additions and 19 deletions.
diff --git a/index.js b/index.js
@@ -1,5 +1,6 @@
 'use strict';
 const fs = require('fs');
+const {spawn} = require('child_process');
 const nconf = require('nconf');
 const cjson = require('cjson');
 const chalk = require('chalk');
@@ -19,15 +20,21 @@ if (nconf.get('version')) {
 
 if (nconf.get('help')) {
   console.log('Options:');
-  console.log('  --help        - Prints this usage info');
-  console.log('  --port n      - Listen port number for HTTP server (default: 3000)');
-  console.log("  --testmode    - Simulate serial port activity, don't open real ports");
-  console.log('  --version     - Prints server version number');
+  console.log('  --help          - Prints this usage info');
+  console.log('  --port n        - Listen port number for HTTP server (default: 3000)');
+  console.log("  --testmode      - Simulate serial port activity, don't open real ports");
+  console.log('  --wrap-cmd cmd  - Spawn `cmd` as a subprocess; kill server when subprocess dies and vice versa');
+  console.log('  --wrap-dir dir  - Working directory for wrapped command');
+  console.log('  --version       - Prints server version number');
   process.exit();
 }
 
 const server = require('./lib/server.js');
-server.start(nconf).catch(console.error);
+server
+  .start(nconf)
+  .then(() => console.log(chalk.blue.bold('Press CTRL+C to quit.')))
+  .then(() => nconf.get('wrap-cmd') && spawnChild())
+  .catch(console.error);
 
 function readConfig(file) {
   if (!fs.existsSync('./config.json')) {
@@ -46,3 +53,34 @@ function verifyConfig(config) {
     throw new Error('Serial ports not configured.');
   }
 }
+
+// Spawn a child process with a suicide pact; parent & child die together.
+function spawnChild() {
+  const cmd = nconf.get('wrap-cmd');
+  const cwd = nconf.get('wrap-dir');
+
+  console.log(chalk.green(`Spawning subprocess '${cmd}'...`))
+  const spawnOpts = {
+    stdio: 'inherit',
+    shell: true,
+    cwd: cwd
+  };
+  const child = spawn(cmd, [], spawnOpts);
+
+  function onChildExit(code) {
+    console.log(chalk.green('Wrapped process exited, server exiting...'));
+    process.removeListener('exit', onExit);
+    process.exit(code);
+  }
+  function onExit(code) {
+    console.log(chalk.green('Exiting, killing subprocess...'))
+    child.removeAllListeners();
+    process.removeListener('exit', onExit);
+    child.kill.bind(child);
+    process.exit(code);
+  }
+
+  process.on('SIGINT', onExit);
+  process.on('exit', onExit);
+  child.on('exit', onChildExit)
+}
diff --git a/lib/server.js b/lib/server.js
@@ -9,34 +9,31 @@ const SerialPort = require('serialport');
 const chalk = require('chalk');
 const xml2js = require('xml2js');
 const ButtonStatus = require('./buttonStatus');
+let httpServer = null;
 
 module.exports = {start, stop};
 
 // Expects a config object with a .get() function for looking up values by key.
 async function start(config) {
   const serverPort = config.get('port');
+  const serialPortNames = config.get('serialPorts');
+
+  // Read configs and create things.
   const mappings = await readMappings(config.get('mappingFiles'));
-  const buttonStatuses = createButtonStatuses(config.get('serialPorts').length, mappings);
-  const serialPorts = openSerialPorts(config.get('serialPorts'));
+  const buttonStatuses = createButtonStatuses(serialPortNames.length, mappings);
+  const serialPorts = openSerialPorts(serialPortNames);
 
-  // Bind serial port data events to button status trackers.
-  for (let i = 0; i < serialPorts.length; i++) {
-    serialPorts[i].on('data', chunk => buttonStatuses[i].update(chunk));
-  }
+  // Connect serial port data inflow to button status decoders.
+  bindPortsToStatuses(serialPorts, buttonStatuses);
 
+  // Start servers.
   const app = startApp(config, buttonStatuses);
-  const httpServer = http.createServer(app);
+  httpServer = await startHTTPServer(app, serverPort);
   const wsServer = startWebSocketServer(config, httpServer, buttonStatuses);
-
-  console.log(chalk.yellow(`Starting server on port ${serverPort}...`));
-  httpServer.listen(serverPort, function listening() {
-    console.log(chalk.yellow.bold(`Server started on port ${httpServer.address().port}.`));
-    console.log(chalk.blue.bold(`Visit http://localhost:${serverPort}/ to see a demo status page.`));
-  });
 }
 
 function stop(done) {
-  if (done) setImmediate(done);
+  httpServer.close(done || (()=>{}));
 }
 
 async function readMappings(mappingFiles) {
@@ -86,6 +83,12 @@ function openSerialPorts(portNames, testmode) {
   });
 }
 
+function bindPortsToStatuses(serialPorts, buttonStatuses) {
+  for (let i = 0; i < serialPorts.length; i++) {
+    serialPorts[i].on('data', chunk => buttonStatuses[i].update(chunk));
+  }
+}
+
 function startApp(config, buttonStatuses) {
   const testmode = config.get('testmode');
   const serialPorts = config.get('serialPorts');
@@ -113,6 +116,19 @@ function startApp(config, buttonStatuses) {
   return app;
 }
 
+function startHTTPServer(app, serverPort) {
+  return new Promise(resolve => {
+    console.log(chalk.yellow(`Starting server on port ${serverPort}...`));
+
+    let httpServer = http.createServer(app);
+    httpServer.listen(serverPort, function listening() {
+      console.log(chalk.yellow.bold(`Server started on port ${httpServer.address().port}.`));
+      console.log(chalk.blue.bold(`Visit http://localhost:${serverPort}/ to see a demo status page.`));
+      resolve(httpServer);
+    });
+  });
+}
+
 function startWebSocketServer(config, httpServer, buttonStatuses) {
   const testmode = config.get('testmode');
   const serialPorts = config.get('serialPorts');