add support for AWS autoscaling (#10)

app.js

@@ -27,6 +27,7 @@ const {
 });
 const StatsCollector = require('@jambonz/stats-collector');
 const stats = new StatsCollector(logger);
+const {LifeCycleEvents} = require('./lib/constants');
 const setNameRtp = `${(process.env.JAMBONES_CLUSTER_ID || 'default')}:active-rtp`;
 const rtpServers = [];
 const setName = `${(process.env.JAMBONES_CLUSTER_ID || 'default')}:active-sip`;
@@ -48,7 +49,7 @@ const {
   database: process.env.JAMBONES_MYSQL_DATABASE,
   connectionLimit: process.env.JAMBONES_MYSQL_CONNECTION_LIMIT || 10
 }, logger);
-const {createSet, retrieveSet, addToSet, incrKey, decrKey} = require('@jambonz/realtimedb-helpers')({
+const {createSet, retrieveSet, addToSet, removeFromSet, incrKey, decrKey} = require('@jambonz/realtimedb-helpers')({
   host: process.env.JAMBONES_REDIS_HOST || 'localhost',
   port: process.env.JAMBONES_REDIS_PORT || 6379
 }, logger);
@@ -108,7 +109,9 @@ if (process.env.DRACHTIO_HOST) {
       else if (arr && 'tcp' === arr[1] && matcher.contains(arr[2])) {
         const hostport = `${arr[2]}:${arr[3]}`;
         logger.info(`adding sbc private address to redis: ${hostport}`);
-        addToSet(setName, hostport);
+        srf.locals.addToRedis = () => addToSet(setName, hostport);
+        srf.locals.removeFromRedis = () => removeFromSet(setName, hostport);
+        srf.locals.addToRedis();
       }
     }
   });
@@ -189,4 +192,16 @@ else {
   getActiveRtpServers();
 }
 
+const {lifecycleEmitter} = require('./lib/autoscale-manager')(logger);
+
+/* if we are scaling in, check every so often if call count has gone to zero */
+setInterval(async() => {
+  if (lifecycleEmitter.operationalState === LifeCycleEvents.ScaleIn) {
+    if (0 === activeCallIds.size) {
+      logger.info('scale-in complete now that calls have dried up');
+      lifecycleEmitter.scaleIn();
+    }
+  }
+}, 20000);
+
 module.exports = {srf, logger};

lib/autoscale-manager.js

@@ -0,0 +1,63 @@
+const noopLogger = {info: () => {}, error: () => {}};
+const {LifeCycleEvents} = require('./constants');
+const Emitter = require('events');
+
+module.exports = (logger) => {
+  logger = logger || noopLogger;
+
+  // listen for SNS lifecycle changes
+  let lifecycleEmitter = new Emitter();
+  lifecycleEmitter.dryUpCalls = false;
+  if (process.env.AWS_SNS_TOPIC_ARM && process.env.AWS_REGION) {
+
+    (async function() {
+      try {
+        lifecycleEmitter = await require('./aws-sns-lifecycle')(logger);
+
+        lifecycleEmitter
+          .on(LifeCycleEvents.ScaleIn, async() => {
+            logger.info('AWS scale-in notification: begin drying up calls');
+            lifecycleEmitter.dryUpCalls = true;
+            lifecycleEmitter.operationalState = LifeCycleEvents.ScaleIn;
+
+            const {srf} = require('..');
+            const {activeCallIds, removeFromRedis} = srf.locals;
+
+            /* remove our private IP from the set of active SBCs so rtp and fs know we are gone */
+            removeFromRedis();
+
+            /* if we have zero calls, we can complete the scale-in right now */
+            const calls = activeCallIds.size;
+            if (0 === calls) {
+              logger.info('scale-in can complete immediately as we have no calls in progress');
+              lifecycleEmitter.completeScaleIn();
+            }
+            else {
+              logger.info(`${calls} calls in progress; scale-in will complete when they are done`);
+            }
+          })
+          .on(LifeCycleEvents.StandbyEnter, () => {
+            lifecycleEmitter.dryUpCalls = true;
+            const {srf} = require('..');
+            const {removeFromRedis} = srf.locals;
+            removeFromRedis();
+
+            logger.info('AWS enter pending state notification: begin drying up calls');
+          })
+          .on(LifeCycleEvents.StandbyExit, () => {
+            lifecycleEmitter.dryUpCalls = false;
+            const {srf} = require('..');
+            const {addToRedis} = srf.locals;
+            addToRedis();
+
+            logger.info('AWS exit pending state notification: re-enable calls');
+          });
+      } catch (err) {
+        logger.error({err}, 'Failure creating SNS notifier, lifecycle events will be disabled');
+      }
+    })();
+  }
+
+  return {lifecycleEmitter};
+};
+

lib/aws-sns-lifecycle.js

@@ -0,0 +1,186 @@
+const Emitter = require('events');
+const bent = require('bent');
+const assert = require('assert');
+const PORT = process.env.AWS_SNS_PORT || 3001;
+const {LifeCycleEvents} = require('./constants');
+const express = require('express');
+const app = express();
+const getString = bent('string');
+const AWS = require('aws-sdk');
+const sns = new AWS.SNS({apiVersion: '2010-03-31'});
+const autoscaling = new AWS.AutoScaling({apiVersion: '2011-01-01'});
+const {Parser} = require('xml2js');
+const parser = new Parser();
+const {validatePayload} = require('verify-aws-sns-signature');
+
+AWS.config.update({region: process.env.AWS_REGION});
+
+class SnsNotifier extends Emitter {
+  constructor(logger) {
+    super();
+
+    this.logger = logger;
+  }
+
+  async _handlePost(req, res) {
+    try {
+      const parsedBody = JSON.parse(req.body);
+      this.logger.debug({headers: req.headers, body: parsedBody}, 'Received HTTP POST from AWS');
+      if (!validatePayload(parsedBody)) {
+        this.logger.info('incoming AWS SNS HTTP POST failed signature validation');
+        return res.sendStatus(403);
+      }
+      this.logger.debug('incoming HTTP POST passed validation');
+      res.sendStatus(200);
+
+      switch (parsedBody.Type) {
+        case 'SubscriptionConfirmation':
+          const response = await getString(parsedBody.SubscribeURL);
+          const result = await parser.parseStringPromise(response);
+          this.subscriptionArn = result.ConfirmSubscriptionResponse.ConfirmSubscriptionResult[0].SubscriptionArn[0];
+          this.subscriptionRequestId = result.ConfirmSubscriptionResponse.ResponseMetadata[0].RequestId[0];
+          this.logger.info({
+            subscriptionArn: this.subscriptionArn,
+            subscriptionRequestId: this.subscriptionRequestId
+          }, 'response from SNS SubscribeURL');
+          const data = await this.describeInstance();
+          this.lifecycleState = data.AutoScalingInstances[0].LifecycleState;
+          break;
+
+        case 'Notification':
+          if (parsedBody.Subject.startsWith('Auto Scaling:  Lifecycle action \'TERMINATING\'')) {
+            const msg = JSON.parse(parsedBody.Message);
+            if (msg.EC2InstanceId === this.instanceId) {
+              this.logger.info('SnsNotifier - begin scale-in operation');
+              this.scaleInParams = {
+                AutoScalingGroupName: msg.AutoScalingGroupName,
+                LifecycleActionResult: 'CONTINUE',
+                LifecycleActionToken: msg.LifecycleActionToken,
+                LifecycleHookName: msg.LifecycleHookName
+              };
+              this.operationalState = LifeCycleEvents.ScaleIn;
+              this.emit(LifeCycleEvents.ScaleIn);
+              this.unsubscribe();
+            }
+            else {
+              this.logger.debug(`SnsNotifier - instance ${msg.EC2InstanceId} is scaling in (not us)`);
+            }
+          }
+          break;
+
+        default:
+          this.logger.info(`unhandled SNS Post Type: ${parsedBody.Type}`);
+      }
+
+    } catch (err) {
+      this.logger.error({err}, 'Error processing SNS POST request');
+      if (!res.headersSent) res.sendStatus(500);
+    }
+  }
+
+  async init() {
+    try {
+      this.logger.debug('SnsNotifier: retrieving instance data');
+      this.instanceId = await getString('http://169.254.169.254/latest/meta-data/instance-id');
+      this.publicIp = await getString('http://169.254.169.254/latest/meta-data/public-ipv4');
+      this.snsEndpoint = `http://${this.publicIp}:${PORT}`;
+      this.logger.info({
+        instanceId: this.instanceId,
+        publicIp: this.publicIp,
+        snsEndpoint: this.snsEndpoint
+      }, 'retrieved AWS instance data');
+
+      // start listening
+      app.use(express.urlencoded({ extended: true }));
+      app.use(express.json());
+      app.use(express.text());
+      app.post('/', this._handlePost.bind(this));
+      app.use((err, req, res, next) => {
+        this.logger.error(err, 'burped error');
+        res.status(err.status || 500).json({msg: err.message});
+      });
+      app.listen(PORT);
+
+    } catch (err) {
+      this.logger.error({err}, 'Error retrieving AWS instance metadata');
+    }
+  }
+
+  async subscribe() {
+    try {
+      const response = await sns.subscribe({
+        Protocol: 'http',
+        TopicArn: process.env.AWS_SNS_TOPIC_ARM,
+        Endpoint: this.snsEndpoint
+      }).promise();
+      this.logger.info({response}, `response to SNS subscribe to ${process.env.AWS_SNS_TOPIC_ARM}`);
+    } catch (err) {
+      this.logger.error({err}, `Error subscribing to SNS topic arn ${process.env.AWS_SNS_TOPIC_ARM}`);
+    }
+  }
+
+  async unsubscribe() {
+    if (!this.subscriptionArn) throw new Error('SnsNotifier#unsubscribe called without an active subscription');
+    try {
+      const response = await sns.unsubscribe({
+        SubscriptionArn: this.subscriptionArn
+      }).promise();
+      this.logger.info({response}, `response to SNS unsubscribe to ${process.env.AWS_SNS_TOPIC_ARM}`);
+    } catch (err) {
+      this.logger.error({err}, `Error unsubscribing to SNS topic arn ${process.env.AWS_SNS_TOPIC_ARM}`);
+    }
+  }
+
+  completeScaleIn() {
+    assert(this.scaleInParams);
+    autoscaling.completeLifecycleAction(this.scaleInParams, (err, response) => {
+      if (err) return this.logger.error({err}, 'Error completing scale-in');
+      this.logger.info({response}, 'Successfully completed scale-in action');
+    });
+  }
+
+  describeInstance() {
+    return new Promise((resolve, reject) => {
+      if (!this.instanceId) return reject('instance-id unknown');
+      autoscaling.describeAutoScalingInstances({
+        InstanceIds: [this.instanceId]
+      }, (err, data) => {
+        if (err) {
+          this.logger.error({err}, 'Error describing instances');
+          reject(err);
+        } else {
+          this.logger.info({data}, 'SnsNotifier: describeInstance');
+          resolve(data);
+        }
+      });
+    });
+  }
+
+}
+
+module.exports = async function(logger) {
+  const notifier = new SnsNotifier(logger);
+  await notifier.init();
+  await notifier.subscribe();
+
+  process.on('SIGHUP', async() => {
+    try {
+      const data = await notifier.describeInstance();
+      const state = data.AutoScalingInstances[0].LifecycleState;
+      if (state !== notifier.lifecycleState) {
+        notifier.lifecycleState = state;
+        switch (state) {
+          case 'Standby':
+            notifier.emit(LifeCycleEvents.StandbyEnter);
+            break;
+          case 'InService':
+            notifier.emit(LifeCycleEvents.StandbyExit);
+            break;
+        }
+      }
+    } catch (err) {
+      console.error(err);
+    }
+  });
+  return notifier;
+};

lib/constants.json

@@ -0,0 +1,7 @@
+{
+  "LifeCycleEvents" : {
+    "ScaleIn": "scale-in",
+    "StandbyEnter": "standby-enter",
+    "StandbyExit": "standby-exit"
+  }
+}

package.json

@@ -27,10 +27,15 @@
   "dependencies": {
     "@jambonz/db-helpers": "^0.6.12",
     "@jambonz/http-authenticator": "^0.2.0",
-    "@jambonz/realtimedb-helpers": "^0.4.3",
+    "@jambonz/realtimedb-helpers": "^0.4.8",
     "@jambonz/rtpengine-utils": "^0.1.12",
     "@jambonz/stats-collector": "^0.1.5",
     "@jambonz/time-series": "^0.1.5",
+    "aws-sdk": "^2.848.0",
+    "bent": "^7.3.12",
+    "express": "^4.17.1",
+    "verify-aws-sns-signature": "^0.0.6",
+    "xml2js": "^0.4.23",
     "cidr-matcher": "^2.1.1",
     "debug": "^4.3.1",
     "drachtio-fn-b2b-sugar": "0.0.12",