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https://github.com/bbc/sqs-consumer

Build Amazon Simple Queue Service (SQS) based applications without the boilerplate
https://github.com/bbc/sqs-consumer

aws ignorearchive javascript nodejs polling sqs

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Build Amazon Simple Queue Service (SQS) based applications without the boilerplate

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# sqs-consumer



[![NPM downloads](https://img.shields.io/npm/dm/sqs-consumer.svg?style=flat)](https://npmjs.org/package/sqs-consumer)

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Build SQS-based applications without the boilerplate. Just define an async function that handles the SQS message processing.



## Installation



To install this package, simply enter the following command into your terminal (or the variant of whatever package manager you are using):



```bash

npm install sqs-consumer

```



If you would like to use JSR instead, you can find the package [here](https://jsr.io/@bbc/sqs-consumer).



### Node version



We will only support Node versions that are actively or security supported by the Node team. If you are still using an Node 14, please use a version of this library before the v7 release, if you are using Node 16, please use a version before the v7.3.0 release.



## Documentation



Visit [https://bbc.github.io/sqs-consumer/](https://bbc.github.io/sqs-consumer/) for the full API documentation.



## Usage



```js

import { Consumer } from "sqs-consumer";



const app = Consumer.create({

  queueUrl: "https://sqs.eu-west-1.amazonaws.com/account-id/queue-name",

  handleMessage: async (message) => {

    // do some work with `message`

  },

});



app.on("error", (err) => {

  console.error(err.message);

});



app.on("processing_error", (err) => {

  console.error(err.message);

});



app.start();

```



- The queue is polled continuously for messages using [long polling](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-long-polling.html).

- Throwing an error (or returning a rejected promise) from the handler function will cause the message to be left on the queue. An [SQS redrive policy](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/SQSDeadLetterQueue.html) 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 here](https://bbc.github.io/sqs-consumer/interfaces/ConsumerOptions.html#batchSize).

  - It's also important to await any processing that you are doing to ensure that messages are processed one at a time.

- By default, messages that are sent to the `handleMessage` and `handleMessageBatch` functions will be considered as processed if they return without an error.

  - To acknowledge individual messages, please return the message that you want to acknowledge if you are using `handleMessage` or the messages for `handleMessageBatch`.

    - To note, returning an empty object or an empty array will be considered an acknowledgement of no message(s) and will result in no messages being deleted. If you would like to change this behaviour, please use the `alwaysAcknowledge` option [detailed here](https://bbc.github.io/sqs-consumer/interfaces/ConsumerOptions.html).

    - By default, if an object or an array is not returned, all messages will be acknowledged.

- Messages are deleted from the queue once the handler function has completed successfully (the above items should also be taken into account).



### Credentials



By default the consumer will look for AWS credentials in the places [specified by the AWS SDK](https://docs.aws.amazon.com/AWSJavaScriptSDK/guide/node-configuring.html#Setting_AWS_Credentials). The simplest option is to export your credentials as environment variables:



```bash

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 [SQS Client](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/clients/client-sqs/classes/sqsclient.html) client.



```js

import { Consumer } from "sqs-consumer";

import { SQSClient } from "@aws-sdk/client-sqs";



const app = Consumer.create({

  queueUrl: "https://sqs.eu-west-1.amazonaws.com/account-id/queue-name",

  handleMessage: async (message) => {

    // ...

  },

  sqs: new SQSClient({

    region: "my-region",

    credentials: {

      accessKeyId: "yourAccessKey",

      secretAccessKey: "yourSecret",

    },

  }),

});



app.on("error", (err) => {

  console.error(err.message);

});



app.on("processing_error", (err) => {

  console.error(err.message);

});



app.on("timeout_error", (err) => {

  console.error(err.message);

});



app.start();

```



### AWS IAM Permissions



Consumer will receive and delete messages from the SQS queue. Ensure `sqs:ReceiveMessage`, `sqs:DeleteMessage`, `sqs:DeleteMessageBatch`, `sqs:ChangeMessageVisibility` and `sqs:ChangeMessageVisibilityBatch` access is granted on the queue being consumed.



## API



### `Consumer.create(options)`



Creates a new SQS consumer using the [defined options](https://bbc.github.io/sqs-consumer/interfaces/ConsumerOptions.html).



### `consumer.start()`



Start polling the queue for messages.



### `consumer.stop(options)`



Stop polling the queue for messages. [You can find the options definition here](https://bbc.github.io/sqs-consumer/interfaces/StopOptions.html).



By default, the value of `abort` is set to `false` which means pre existing requests to AWS SQS will still be made until they have concluded. If you would like to abort these requests instead, pass the abort value as `true`, like so:



`consumer.stop({ abort: true })`



### `consumer.status`



Returns the current status of the consumer.



- `isRunning` - `true` if the consumer has been started and not stopped, `false` if was not started or if it was stopped.

- `isPolling` - `true` if the consumer is actively polling, `false` if it is not.



> **Note:**

> This method is not available in versions before v9.0.0 and replaced the method `isRunning` to supply both running and polling states.



### `consumer.updateOption(option, value)`



Updates the provided option with the provided value.



Please note that any update of the option `pollingWaitTimeMs` will take effect only on next polling cycle.



You can [find out more about this here](https://bbc.github.io/sqs-consumer/classes/Consumer.html#updateOption).



### Events



Each consumer is an [`EventEmitter`](https://nodejs.org/api/events.html) and [emits these events](https://bbc.github.io/sqs-consumer/interfaces/Events.html).



## Contributing



We welcome and appreciate contributions for anyone who would like to take the time to fix a bug or implement a new feature.



But before you get started, [please read the contributing guidelines](https://github.com/bbc/sqs-consumer/blob/main/.github/CONTRIBUTING.md) and [code of conduct](https://github.com/bbc/sqs-consumer/blob/main/.github/CODE_OF_CONDUCT.md).



## License



SQS Consumer is distributed under the Apache License, Version 2.0, see [LICENSE](https://github.com/bbc/sqs-consumer/blob/main/LICENSE) for more information.