Possible to stream dynamodb INSERT event directly to an SNS topic?

Serverless Framework
1

I want to be able to react to dynamodb inserts for a certain table and basically post events to a SNS topic…

Do I need dynamodb to trigger a lambda first which would then have some logic to detect insert v update and subsequently post a sns event? OR is it possible to have dynamodb automatically put INSERT messages on SNS queue directly via some declarative config in serverless.yaml ?

2

Yes. You need to attach a Lambda to the DDB stream the write the message to SNS.

3

I’m trying to stream dynamodb inserts to a lambda trigger but having some issues:

  1. general config seems to be wrong

  2. Is there a way I can get around having to hardcode the latest arn for the dynamodb stream ?

    functions:

    companyInfoByDateInsert:
    handler: com.serverless.handlers.CompanyInfoByDateInsertHandler
    events:

    • stream:
      arn : arn:aws:dynamodb:us-east-1:xxxx:table/${self:provider.environment.companyInfoByDateDynamoDbTable}
      batchSize: 100
      enabled: true

    resources:
    Resources:
    StockpickerDynamoDbTable:
    Type: ‘AWS::DynamoDB::Table’
    DeletionPolicy: Retain
    Properties:
    TableName: ${self:provider.environment.companyInfoByDateDynamoDbTable}
    AttributeDefinitions:
    -
    AttributeName: date
    AttributeType: S
    -
    AttributeName: ticker
    AttributeType: S
    KeySchema:
    -
    AttributeName: date
    KeyType: HASH
    -
    AttributeName: ticker
    KeyType: RANGE

         ProvisionedThroughput:
       ReadCapacityUnits: 1
       WriteCapacityUnits: 1

     StreamSpecification:
       StreamViewType: NEW_IMAGE

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4

The streams documentation has an example https://serverless.com/framework/docs/providers/aws/events/streams/

- stream:
    type: dynamodb
    arn:
      Fn::GetAtt:
        - MyDynamoDbTable
        - StreamArn

Also checkout the CloudFormation docs http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-getatt.html

I believe the batchSize and enabled options you’re trying to use only apply to Kinesis streams.

5

it just will not set up the trigger on my lambda - can you see anything obvious that is wrong here:

this time there is even nothing in the lambda trigger tab

service: groovy-stock-picker

# You can pin your service to only deploy with a specific Serverless version
# Check out our docs for more details
# frameworkVersion: "=X.X.X"

provider:
  name: aws
  runtime: java8
  timeout: 15


  iamRoleStatements:
    - Effect: "Allow"
      Action:
        - "lambda:InvokeFunction"
        - "dynamodb:*"
      Resource: "*"




    companyInfoByDateDynamoDbTable: companyInfoByDate-${self:service}-${opt:stage,self:provider.stage}
    companyReportsJobByDateDynamoDbTable: companyReportsJobByDate-${self:service}-${opt:stage,self:provider.stage}


package:
  artifact: build/distributions/hello.zip




functions:
  hello:
    handler: com.serverless.handlers.Handler

  getReportingCompaniesForDate:
    handler: com.serverless.handlers.GetReportingCompaniesForDateHandler

  companyInfoByDateInsert:
    handler: com.serverless.handlers.CompanyInfoByDateInsertHandler
    events:
      - stream:
        type: dynamodb
        arn:
          Fn::GetAtt:
            - ${self:provider.environment.companyInfoByDateDynamoDbTable}
            - arn:aws:dynamodb:us-east-1:xxx:table/companyInfoByDate-groovy-stock-picker-dev/stream/2017-09-16T17:28:06.387

# you can add CloudFormation resource templates here
resources:
  Resources:
    StockpickerDynamoDbTable:
      Type: 'AWS::DynamoDB::Table'
      DeletionPolicy: Delete
      Properties:
        TableName: ${self:provider.environment.companyInfoByDateDynamoDbTable}
        AttributeDefinitions:
          -
            AttributeName: date
            AttributeType: S
          -
            AttributeName: ticker
            AttributeType: S
        KeySchema:
          -
            AttributeName: date
            KeyType: HASH
          -
            AttributeName: ticker
            KeyType: RANGE

        ProvisionedThroughput:
          ReadCapacityUnits: 1
          WriteCapacityUnits: 1

        StreamSpecification:
          StreamViewType: NEW_IMAGE