init commit

server/api/amqp.js

@@ -0,0 +1,100 @@
+'use strict';
+exports.__esModule = true;
+exports.publishQueueConnection = void 0;
+// This script fetches queued messages from RabbitMQ and delivers these to SMTP
+var nodemailer = require("nodemailer");
+var amqp = require("amqp");
+var queueHost = process.env.AMQP_URL;
+var queueName = 'outgoing';
+var smtpHost = {
+    host: process.env.NODEMAILER_HOST,
+    port: process.env.NODEMAILER_PORT,
+    // NB! Must be pooled connection, otherwise 'idle' is never fired and nothing gets sent
+    pool: true,
+    auth: {
+        user: process.env.NODEMAILER_USER,
+        pass: process.env.NODEMAILER_PASS
+    },
+    tls: {
+        // testserver uses self signed certificate, so we need to lax a bit
+        rejectUnauthorized: false
+    },
+    logger: false
+};
+// array of prefetched messages waiting for delivery
+var waiting = [];
+// Create a SMTP transporter object
+var transporter = nodemailer.createTransport(smtpHost, {
+    // default message fields
+    from: process.env.SENDER_ADDRESS
+});
+// Create connection to RabbitMQ
+var queueConnection = amqp.createConnection({
+    url: queueHost
+});
+queueConnection.on('error', function (e) {
+    console.log('Error from amqp: ', e);
+});
+queueConnection.on('ready', function (err) {
+    console.log('AMPQ server is running on port 5672.');
+    queueConnection.queue(queueName, { durable: true }, function (q) {
+        q.bind('#');
+        q.subscribe({
+            ack: true,
+            prefetchCount: 10 // prefetch 10 messages
+        }, function (message, headers, deliveryInfo, ack) {
+            // check if the message object is even valid
+            if (!message || !message.to) {
+                console.log('Invalid message, skipping');
+                // reject, do not requeue
+                return ack.reject();
+            }
+            // push to cache
+            waiting.push({
+                message: message,
+                deliveryTag: deliveryInfo.deliveryTag.toString('hex'),
+                ack: ack
+            });
+            // try to flush cached messages by sending these to SMTP
+            flushWaitingMessages();
+        });
+    });
+});
+// Whenever transporter gets into idling, try to send some mail
+transporter.on('idle', flushWaitingMessages);
+// Flushes cached messages to nodemailer for delivery
+function flushWaitingMessages() {
+    // actual send function
+    var send = function (data) {
+        // sendMail does not immediatelly send, instead it tries to allocate a free connection to SMTP server
+        // and if fails, then pushes the message into internal queue. As we only prefetch 10 messages
+        // then the internal queue can never grow into something too large. At most there will be 5 messages
+        // idling in the queue (another 5 are being currently sent by the default number of 5 connections)
+        transporter.sendMail(data.message, function (err, info) {
+            if (err) {
+                console.log('Message failed (%s): %s', data.deliveryTag, err.message);
+                // reject and requeue on error (wait 1 sec. before requeueing)
+                // NB! If the failure is permanent then this approach results in an
+                // infinite loop since failing message is never removed from the queue
+                setTimeout(function () {
+                    data.ack.reject(true);
+                }, 1000);
+                return;
+            }
+            console.log('Message delivered (%s): %s', data.deliveryTag, info.response);
+            data.ack.acknowledge();
+        });
+    };
+    // send cached messages if transporter is idling
+    while (transporter.isIdle() && waiting.length) {
+        send(waiting.shift());
+    }
+}
+exports.publishQueueConnection = function (mailOptions) {
+    console.log('publishQueueConnection');
+    queueConnection.publish(queueName, mailOptions, function (err) {
+        if (err) {
+            console.log(err);
+        }
+    });
+};