19: Implement cluster discovery using dns

src/core/clusterDnsEndPointDiscoverer.js

@@ -1,5 +1,6 @@
 var http = require('http');
 var util = require('util');
+var dns = require('dns');
 var GossipSeed = require('../gossipSeed');
 
 function NodeEndPoints(tcpEndPoint, secureTcpEndPoint) {
@@ -61,37 +62,37 @@ ClusterDnsEndPointDiscoverer.prototype.discover = function(failedTcpEndPoint) {
  */
 ClusterDnsEndPointDiscoverer.prototype._discoverEndPoint = function (failedTcpEndPoint) {
   try {
-    var gossipCandidates = this._oldGossip
+    var mainPromise = this._oldGossip
-      ? this._getGossipCandidatesFromOldGossip(this._oldGossip, failedTcpEndPoint)
+      ? Promise.resolve(this._getGossipCandidatesFromOldGossip(this._oldGossip, failedTcpEndPoint))
       : this._getGossipCandidatesFromDns();
     var self = this;
-    var promise = Promise.resolve();
     var j = 0;
-    self._log.debug('Gossip candidates', gossipCandidates);
+    return mainPromise.then(function (gossipCandidates) {
+      var loopPromise = Promise.resolve();
       for (var i = 0; i < gossipCandidates.length; i++) {
-      promise = promise.then(function (endPoints) {
+        loopPromise = loopPromise.then(function (endPoints) {
           if (endPoints) return endPoints;
-
           return self._tryGetGossipFrom(gossipCandidates[j++])
             .then(function (gossip) {
-            if (gossip === null || gossip.members === null || gossip.members.length === 0)
+              if (!gossip || !gossip.members || gossip.members.length === 0)
                 return;
               var bestNode = self._tryDetermineBestNode(gossip.members);
-            if (bestNode !== null) {
+              if (bestNode) {
                 self._oldGossip = gossip.members;
                 return bestNode;
               }
             });
         });
       }
-    return promise;
+      return loopPromise;
+    });
   } catch (e) {
     return Promise.reject(e);
   }
 };
 
 ClusterDnsEndPointDiscoverer.prototype._getGossipCandidatesFromOldGossip = function (oldGossip, failedTcpEndPoint) {
-  if (failedTcpEndPoint === null) return this._arrangeGossipCandidates(oldGossip);
+  if (!failedTcpEndPoint) return this._arrangeGossipCandidates(oldGossip);
   var gossipCandidates = oldGossip.filter(function(x) {
     return !(x.externalTcpPort === failedTcpEndPoint.port && x.externalTcpIp === failedTcpEndPoint.host);
   });
@@ -115,20 +116,33 @@ ClusterDnsEndPointDiscoverer.prototype._arrangeGossipCandidates = function (memb
 };
 
 ClusterDnsEndPointDiscoverer.prototype._getGossipCandidatesFromDns = function () {
-  var endpoints = [];
+  var self = this;
-  if(this._gossipSeeds !== null && this._gossipSeeds.length > 0)
+  return new Promise(function (resolve, reject) {
-  {
+    if (self._gossipSeeds && self._gossipSeeds.length > 0) {
-    endpoints = this._gossipSeeds;
+      var endpoints = self._gossipSeeds;
+      self._randomShuffle(endpoints, 0, endpoints.length - 1);
+      resolve(endpoints);
     }
-  else
+    else {
-  {
+      const dnsOptions = {
-    //TODO: dns resolve
+        family: 4,
-    throw new Error('Not implemented.');
+        hints: dns.ADDRCONFIG | dns.V4MAPPED,
-    //endpoints = ResolveDns(_clusterDns).Select(x => new GossipSeed(new IPEndPoint(x, _managerExternalHttpPort))).ToArray();
+        all: true
+      };
+      dns.lookup(self._clusterDns, dnsOptions, function (err, addresses) {
+        if (err) {
+          return reject(err);
         }
-
+        if (!addresses || addresses.length === 0) {
-  this._randomShuffle(endpoints, 0, endpoints.length-1);
+          return reject(new Error('No result from dns lookup for ' + self._clusterDns));
-  return endpoints;
+        }
+        var endpoints = addresses.map(function (x) {
+          return new GossipSeed({host: x.address, port: self._managerExternalHttpPort});
+        });
+        resolve(endpoints);
+      });
+    }
+  });
 };
 
 ClusterDnsEndPointDiscoverer.prototype._tryGetGossipFrom = function (endPoint) {
@@ -143,9 +157,9 @@ ClusterDnsEndPointDiscoverer.prototype._tryGetGossipFrom = function (endPoint) {
   this._log.info('Try get gossip from', endPoint);
   var self = this;
   return new Promise(function (resolve, reject) {
-    try {
+    var timedout = false;
-      http
+    http.request(options, function (res) {
-        .request(options, function (res) {
+          if (timedout) return;
           var result = '';
           if (res.statusCode !== 200) {
             self._log.info('Trying to get gossip from', endPoint, 'failed with status code:', res.statusCode);
@@ -166,16 +180,15 @@ ClusterDnsEndPointDiscoverer.prototype._tryGetGossipFrom = function (endPoint) {
         })
         .setTimeout(self._gossipTimeout, function () {
           self._log.info('Trying to get gossip from', endPoint, 'timed out.');
+          timedout = true;
           resolve();
         })
         .on('error', function (e) {
+          if (timedout) return;
           self._log.info('Trying to get gossip from', endPoint, 'failed with error:', e);
           resolve();
         })
         .end();
-    } catch(e) {
-      reject(e);
-    }
   });
 };
 

test/cluster/dns_test.js

@@ -0,0 +1,32 @@
+var client = require('../../src/client');
+var uuid = require('uuid');
+
+var settings = {
+  log: {
+    info: console.log,
+    error: console.log,
+    debug: console.log
+  }
+};
+var conn = client.createConnection(settings, "discover://es.nicdex.com:2113");
+console.log('Connecting...');
+conn.on('connected', function (tcpEndPoint) {
+  console.log('Connected to', tcpEndPoint);
+  setTimeout(function () {
+    conn.appendToStream('test-' + uuid.v4(), client.expectedVersion.noStream, [
+      client.createJsonEventData(uuid.v4(), {abc: 123}, {}, 'myEvent')
+    ]);
+  }, 5000);
+});
+conn.on('error', function (err) {
+  console.log(err.stack);
+});
+conn.on('closed', function (reason) {
+  console.log('Connection closed:', reason);
+  process.exit(-1);
+});
+conn.connect()
+  .catch(function (err) {
+    console.log(err.stack);
+    process.exit(-1);
+  });

test/cluster/gossipSeeds_test.js

@@ -9,15 +9,14 @@ var settings = {
   }
 };
 var gossipSeeds = [
-  new client.GossipSeed({host: '192.168.33.10', port: 1113}),
+  new client.GossipSeed({host: '192.168.33.10', port: 2113}),
-  new client.GossipSeed({host: '192.168.33.11', port: 1113}),
+  new client.GossipSeed({host: '192.168.33.11', port: 2113}),
-  new client.GossipSeed({host: '192.168.33.12', port: 1113})
+  new client.GossipSeed({host: '192.168.33.12', port: 2113})
 ];
-
 var conn = client.createConnection(settings, gossipSeeds);
 console.log('Connecting...');
 conn.on('connected', function (tcpEndPoint) {
-  console.log('Connect to', tcpEndPoint);
+  console.log('Connected to', tcpEndPoint);
   setTimeout(function () {
     conn.appendToStream('test-' + uuid.v4(), client.expectedVersion.noStream, [
       client.createJsonEventData(uuid.v4(), {abc: 123}, {}, 'myEvent')