pablovilas/sqs-consumer

Build SQS-based Node applications without the boilerplate

sqs-consumer

Build SQS-based applications without the boilerplate. Just define a function that receives an SQS message and call a callback when the message has been processed.

Installation

npm install sqs-consumer

Usage

var Consumer = require('sqs-consumer');

var app = Consumer.create({
  queueUrl: 'https://sqs.eu-west-1.amazonaws.com/account-id/queue-name',
  handleMessage: function (message, done) {
    // do some work with `message`
    done();
  }
});

app.on('error', function (err) {
  console.log(err.message);
});

app.start();

• The queue is polled continuously for messages using long polling.
• Messages are deleted from the queue once done() is called.
• Calling done(err) with an error object will cause the message to be left on the queue. An SQS redrive policy can be used to move messages that cannot be processed to a dead letter queue.
• By default messages are processed one at a time – a new message won't be received until the first one has been processed. To process messages in parallel, use the batchSize option detailed below.

Credentials

By default the consumer will look for AWS credentials in the places specified by the AWS SDK. The simplest option is to export your credentials as environment variables:

export AWS_SECRET_ACCESS_KEY=...
export AWS_ACCESS_KEY_ID=...

If you need to specify your credentials manually, you can use a pre-configured instance of the AWS SQS client:

var Consumer = require('sqs-consumer');
var AWS = require('aws-sdk');

AWS.config.update({
  region: 'eu-west-1',
  accessKeyId: '...',
  secretAccessKey: '...'
});

var app = Consumer.create({
  queueUrl: 'https://sqs.eu-west-1.amazonaws.com/account-id/queue-name',
  handleMessage: function (message, done) {
    // ...
  },
  sqs: new AWS.SQS();
});

API

Consumer.create(options)

Creates a new SQS consumer.

Options

• queueUrl - String - The SQS queue URL
• region - String - The AWS region (default eu-west-1)
• handleMessage - Function - A function to be called whenever a message is received. Receives an SQS message object as its first argument and a function to call when the message has been handled as its second argument (i.e. handleMessage(message, done)).
• attributeNames - Array - List of queue attributes to retrieve (i.e. ['All', 'ApproximateFirstReceiveTimestamp', 'ApproximateReceiveCount']).
• messageAttributeNames - Array - List of message attributes to retrieve (i.e. ['name', 'address']).
• batchSize - Number - The number of messages to request from SQS when polling (default 1). This cannot be higher than the AWS limit of 10.
• visibilityTimeout - Number - The duration (in seconds) that the received messages are hidden from subsequent retrieve requests after being retrieved by a ReceiveMessage request.
• waitTimeSeconds - Number - The duration (in seconds) for which the call will wait for a message to arrive in the queue before returning.
• sqs - Object - An optional AWS SQS object to use if you need to configure the client manually

consumer.start()

Start polling the queue for messages.

consumer.stop()

Stop polling the queue for messages.

Events

Each consumer is an EventEmitter and emits the following events:

Event	Params	Description
error	err	Fired when an error occurs interacting with the queue.
processing_error	err	Fired when an error occurs processing the message.
message_received	message	Fired when a message is received.
message_processed	message	Fired when a message is successfully processed and removed from the queue.