Test localtunnel and retry if it failed

bin/probot-run.js

@@ -36,9 +36,13 @@ if (!program.privateKey) {
 }
 
 if (program.tunnel) {
-  const setupTunnel = require('../lib/tunnel');
   try {
-    setupTunnel(program.tunnel, program.port);
+    const setupTunnel = require('../lib/tunnel');
+    setupTunnel(program.tunnel, program.port).then(tunnel => {
+      console.log('Listening on ' + tunnel.url);
+    }).catch(err => {
+      console.warn('Could not open tunnel: ', err.message);
+    });
   } catch (err) {
     console.warn('Run `npm install --save-dev localtunnel` to enable localtunnel.');
   }

lib/tunnel.js

@@ -1,22 +1,44 @@
 // eslint-disable-next-line import/no-extraneous-dependencies, import/no-unresolved
 const localtunnel = require('localtunnel');
+const https = require('https');
 
-module.exports = function (subdomain, port) {
-  if(subdomain !== 'string') {
+module.exports = function setupTunnel(subdomain, port, retries = 0) {
+  if(typeof subdomain !== 'string') {
     subdomain = require('os').userInfo().username;
   }
 
-  const tunnel = localtunnel(port, {subdomain}, (err, tunnel) => {
-    if (err) {
-      console.warn('Could not open tunnel: ', err.message);
-    } else {
-      console.log('Listening on ' + tunnel.url);
-    }
+  return new Promise((resolve, reject) => {
+    localtunnel(port, {subdomain}, (err, tunnel) => {
+      if (err) {
+        reject(err);
+      } else {
+        testTunnel(subdomain).then(() => resolve(tunnel)).catch(err => {
+          if(retries < 3) {
+            console.warn(`Failed to connect to localtunnel.me. Trying again (tries: ${retries + 1})`);
+            resolve(setupTunnel(subdomain, port, retries + 1));
+          } else {
+            reject('Failed to connect to localtunnel.me. Giving up.');
+          }
+        });
+      }
+    });
+  });
+}
+
+// When a tunnel is closed and then immediately reopened (e.g. restarting the
+// server to reload changes), then localtunnel.me may connect but not pass
+// requests through. This test that the tunnel returns 200 for /ping.
+function testTunnel(subdomain) {
+  const options = {
+    host: `${subdomain}.localtunnel.me`,
+    port: 443,
+    path: '/ping',
+    method: 'GET'
+  };
+
+  return new Promise((resolve, reject) => {
+    https.request(options, function(res) {
+      res.statusCode == 200 ? resolve() : reject();
+    }).end();
   });
-
-  tunnel.on('close', () => {
-    console.warn('Local tunnel closed');
-  });
-
-  return tunnel;
 }