Serverless Dynamo Stream Plugin

Creates and connects DynamoDB streams for pre-existing tables with AWS Lambdas using Serverless.

Purpose

Serverless provides the ability to connect your DynamoDB stream with your Lambda out of the box if the Dynamo table is created by Serverless itself, and not only that, if you are trying to do it directly with just serverless, the Dynamo DB table cannot be pre-existing, it will throw an error.

That being said, if you use Terraform, Ansible or any other tool to create your resources outside of Serverless, there is no way to connect your Lambda managed by Serverless with the pre-existing DynamoDB table using a stream.

This plugin solves this problem.

Install

Install the plugin

Using your favorite package manager, simply install the package into your project.

yarn install serverless-dynamo-stream-plugin

or

npm install serverless-dynamo-stream-plugin

Add to serverless.yml

Add the plugin to the plugins section in serverless.yml file.

...
plugins:
  - serverless-dynamo-stream-plugin
...

Usage

existingDynamoStream event

The plugin adds a new type of event for your Dynamo tables called existingDynamoStream. This event accepts the table name and some other parameters (more optional parameters to come in the future). Here is how you can configure your tankHandler Lambda to connect to Battle DynamoDB table stream.

tankHandler:
  handler: handlers/dynamo-streams/tankHandler.process
  events:
    - existingDynamoStream:
        tableName: Battle
        streamType: NEW_IMAGE
        startingPosition: LATEST

Running

There are two ways to run the plugin.

1. sls deploy

The plugin runs automatically after the deploy phase. If you deploy your Serverless infrastructure using the sls deploy command, the plugin starts running automatically once the deploy is finished.

2. sls dynamo-stream

In case you would like to run the plugin on demand, there is a separate command for it called dynamo-stream. Running sls dynamo-stream will not run the deploy and it will only try to connect the lambdas to your DynamoDB streams. Please note that the plugin relies on having a successful serverless deploy first. Meaning that before running your dynamo-stream command, you'll need to make sure all lambdas are already deployed by Serverless.

Release

Initially developed at Commandeer and now Open Sourced for everyone to use.