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https://github.com/rubenkaiser/serverless-offline-eventBridge

A serverless offline plugin that enables eventBridge events
https://github.com/rubenkaiser/serverless-offline-eventBridge

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A serverless offline plugin that enables eventBridge events

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# serverless-offline-aws-eventbridge

A serverless offline plugin that enables aws eventBridge events. As of version 1.4.0 this plugin also supports non javascript handlers.



[![serverless](http://public.serverless.com/badges/v3.svg)](http://www.serverless.com)

[![npm version](https://badge.fury.io/js/serverless-offline-aws-eventbridge.svg)](https://badge.fury.io/js/serverless-offline-aws-eventbridge)

[![npm package](https://img.shields.io/npm/dm/serverless-offline-aws-eventbridge.svg)](https://www.npmjs.com/package/serverless-offline-aws-eventbridge)

[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)



## Docs

- [Installation](#installation)

- [Configure](#configure)

- [Usage](#usage)

- [Versions](#versions)

- [Thanks](#thanks)



## Installation



Install the plugin

```bash

npm install serverless-offline-aws-eventbridge --save

```



Note: if you are running Serverless-(offline) < 10 you need the a version < 2.0.0 of this package since the SLS offline and this eventbridge package were converted to a pure esm module that utilizes the exports functionality. See https://github.com/rubenkaiser/serverless-offline-eventBridge/issues/60



Let serverless know about the plugin, also note the order when combined with serverless webpack and offline

```YAML

plugins:

  - serverless-webpack

  - serverless-offline

  - serverless-offline-aws-eventbridge

```



Configuring the plugin



optional options shown with defaults

```YAML

custom:

  serverless-offline-aws-eventbridge:

    port: 4010 # port to run the eventBridge mock server on

    mockEventBridgeServer: true # Set to false if EventBridge is already mocked by another stack

    hostname: 127.0.0.1 # IP or hostname of existing EventBridge if mocked by another stack

    pubSubPort: 4011 # Port to run the MQ server (or just listen if using an EventBridge Mock server from another stack)

    debug: false # flag to show debug messages

    account: '' # account id that gets passed to the event

    maximumRetryAttempts: 10 # maximumRetryAttempts to retry lambda

    retryDelayMs: 500 # retry delay

    throwRetryExhausted: false # default true

    payloadSizeLimit: "10mb" # Controls the maximum payload size being passed to https://www.npmjs.com/package/bytes (Note: this payload size might not be the same size as your AWS Eventbridge receive)

```



## Publishing and subscribing



Checkout the documentation for AWS eventbridge in serverless framework and the AWS SDK for publishing and subscribing to events.



Scheduled events are also supported. When a cron fires the event object that is sent along is an empty object.



A simple example configuration in serverless with a Lambda function that publishes an event and a Lambda that subscribes to the event.



```YAML

functions:

  publishEvent:

    handler: events.publish

    events:

      - http:

          path: publish

          method: get



  consumeEvent:

    handler: events.consume

    events:

      - eventBridge:

          eventBus: marketing

          pattern:

            source:

              - acme.newsletter.campaign



  scheduledEvent:

    handler: events.scheduled

    events:

      - eventBridge:

          eventBus: marketing

          # run every 5 minutes

          schedule: "cron(0/5 * * * ? *)"

```



The events handler with two functions (publish and consume)



```javascript

  import AWS from 'aws-sdk';



  export const publish = async () => {

    try {

      const eventBridge = new AWS.EventBridge({

        endpoint: 'http://127.0.0.1:4010',

        accessKeyId: "YOURKEY",

        secretAccessKey: "YOURSECRET",

        region: "eu-west-1"

      });



      await eventBridge.putEvents({

        Entries: [

          {

            EventBusName: 'marketing',

            Source: 'acme.newsletter.campaign',

            DetailType: 'UserSignUp',

            Detail: `{ "E-Mail": "[email protected]" }`,

          },

        ]

      }).promise();

      return { statusCode: 200, body: 'published' };

    } catch (e) {

      console.error(e);

      return { statusCode: 400, body: 'could not publish' };

    }

  }



  export const consume = async (event, context) => {

    console.log(event);

    /*

      {

        EventBusName: 'marketing',

        Source: 'acme.newsletter.campaign',

        DetailType: 'UserSignUp',

        Detail: `{ "E-Mail": "[email protected]" }`,

      }

    */

    return { statusCode: 200, body: JSON.stringify(event) };

  }



  export const scheduled = async (event, context) => {

    console.log('scheduled event');

    return { statusCode: 200, body: 'scheduled event' };

  }

```

## Support of EventBridge patterns



EventBridge natively allows a few content-based filters defined here:

https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-event-patterns-content-based-filtering.html



This plugin supports the most common patterns:

* `prefix`

* `anything-but`

* `exists`



```yaml

functions:

  consumeEvent:

    handler: events.consume

    events:

      - eventBridge:

          eventBus: marketing

          pattern:

            source:

              - user

            detail-type:

              - { "anything-but": "deleted" }

            detail:

              firstname: [ { "prefix": "John" } ]

              age: [ { "exists": true } ]

```



The `cidr` filter is yet to be implemented.



## Using CloudFormation intrinsic functions



At some point you might want to use an existing event bus. This plugin needs to somehow resolve intrinsic CloudFormation function calls to event bus names/arns.



An event bus created by the same template, will be referenced using the `!GetAtt` function:



```YAML

functions:



  consumeEvent:

    handler: events.consume

    events:

      - eventBridge:

          eventBus: !GetAtt EventBus.Arn

```



This plugin will look for an `EventBus` resource of type `AWS::Events::EventBus` when deciding whether a function must be triggered.



Or you might use `!ImportValue` to reference an event bus created by another stack.



```YAML

functions:



  consumeEvent:

    handler: events.consume

    events:

      - eventBridge:

          eventBus: !ImportValue EventBusNameFromOtherStack

```



In this case, you won't define the resource directly in your template. To overcome this limitation, you can define a custom object in `serverless.yml` that indicates the mapping between imported keys and the actual event bus name/arn:



```YAML

custom:

  serverless-offline-aws-eventbridge:

    port: 4010 # port to run the eventBridge mock server on

    mockEventBridgeServer: true # Set to false if EventBridge is already mocked by another stack

    hostname: 127.0.0.1 # IP or hostname of existing EventBridge if mocked by another stack

    pubSubPort: 4011 # Port to run the MQ server (or just listen if using an EventBridge mock server from another stack)

    debug: false # flag to show debug messages

    account: '' # account id that gets passed to the event

    imported-event-buses:

      EventBusNameFromOtherStack: event-bus-name-or-arn

```



If your existing EventBridge is mocked on a different host/IP (e.g. When stacks are hosted in Docker containers), then you will also need to specify a `hostname`. If using Docker, you should use the name of the container that mocks the EventBridge (assuming both containers are on the same Docker network).



## Localstack

Plugin is capable of working against locally running docker container of localstack. For example look in [sns-sqs-lambda](examples/typescript//localstack//sns-sqs-lambda/README.md)



**IMPORTANT**

Right now you can run this plugin in "mock server" mode or in localstack mode. By configuring localstack section in your config mock server will not be running.



To configure localstack add configuration:

```YAML

custom:

  serverless-offline-aws-eventbridge:

    localStackConfig:

      localStackEndpoint: http://localhost:4566

```



Or in TypeScript

```typescript

'serverless-offline-aws-eventbridge': {

      localStackConfig: {

        localStackEndpoint: 'http://localhost:4566',

      },

    }

```



For complete guide look in to [TypeScript Localstack example](./examples//typescript//localstack/sns-sqs-lambda).



### Currently supported targets

- [SNS](./examples//typescript//localstack//sns-sqs-lambda//README.md#L7)



## Examples



Two stacks are provided as example:

* `same-stack-publisher-subscriber` runs a mock of Eventbridge. It also has a local (same stack) subscriber

* `remote-subscriber` is a completely independent microservice listening to the eventBridge mock created by the `same-stack-publisher-subscriber` stack



1) Run the first stack in a terminal

```bash

cd examples/same-stack-publisher-subscriber

npm i

serverless offline start

```

2) Run the second stack in a different terminal

```bash

cd examples/remote-subscriber

npm i

serverless offline start

```



3) Publish a test message



Simply hit the exposed API gateway endpoint: http://localhost:3016/dev/publish



You should see the message received on both stacks in the terminal output. You will also notice that the socket connection is resilient to crashes: everything works smoothly as soon as both offline stacks are up and running, regardless of which stack has been restarted last.



## Thanks

This plugin was inspired by the serverless-offline-sns plugin. Also thanks to @sndpl, @guavajellyaaron, @rloomans, @JamesKyburz, @plumsirawit, @damien-thiesson, @carrickkv2, @dnalborczyk and @MichalOleszczuk for their work and PR's.