serverless-transfer-cf-outputs-plugin

This Serverless plugin will transfer CloudFormation output variables from one region to another.

Why would you want to do this?

In case you have a resource that only exists in one region, but you have resources in other regions which want talk to this resource. You can output the ARN or URL of that resource like you normally would, this plugin will import them to other Serverless projects.

Install

npm install --save-dev @xapp/serverless-transfer-cf-outputs-plugin

How

Say you have a Redshift server in the us-east-1. The serverless.yml would be something like this:

serverless.yml

provider:
    ...
    region: us-east-1
    ...

resources:
    Resources:
        myRedshift:
            Type: "AWS::Redshift::Cluster"
            Properties:
                AutomatedSnapshotRetentionPeriod: 7
                ClusterType: "single-node"
                DBName: "mydatabase"
                MasterUsername: "master_user"
                MasterUserPassword: ${ssm:super-secret-password~true}
                NodeType: dc2.large
                ... Further properties

    Outputs:
        RedshiftAddress:
            Value:
                Fn::GetAtt:
                    - myRedshift
                    - Endpoint.Address
            Export:
                Name: redshift-MyRedshiftAddress

            RedshiftPort:
            Value:
                Fn::GetAtt:
                    - myRedshift
                    - Endpoint.Port
            Export:
                Name: redshift-MyRedshiftPort

This is only going to be deployed in one region. It's annoying because the address of this can not be guessed or you have to manually hunt it down and hardcode it in other serverless.yml files which are multi-region.

That's where this plugin comes in. You can create a multi-region Serverless package and import both the port and address of the redshift server.

serverless.yml

plugins:
  - "serverless-transfer-cf-outputs-plugin"

config:
    cfTransfer:
        regions:
            - region: us-east-1
              cfOutputs:
                - redshift-MyRedshiftAddress
                - redshift-MyRedshiftPort

functions:

    myLambdaWhichTalksToRedshift:
        handler: Handler.handler
        role: MyLambdaWhichTalksToRedshiftRole
        environment:
            REDSHIFT_ADDRESS:
                Fn::ImportValue: redshift-MyRedshiftAddress
            REDSHIFT_PORT:
                Fn::ImportValue: redshift-MyRedshiftPort

... The remaining setup.

If deploying in regions other than us-east-1, the plugin will scan the serverless.yml file and replace the Fn::ImportValue statements with the correct exported value from the us-east-1 CloudFormation stack.

Config

The config for this plugin must always be cfTransfer. The full details are:

config:
   cfTransfer:
    config:
      ## Optional: This is the profile which has access to the CloudFormation stack. If not provided, then `default` is used.
      awsProfile: <profile>
    regions:
          ## Required: This is the region the values are exported from.
        - region: <region>
          ## Required: These are the values which are to be imported from the CloudFormation stacks.
          cfOutputs:
            - <output>