README.md

echoDependency

A Lambda function which implements a Custom Resource for Cloud Formation that echoes back the parameters it is given

Installation

Create a Role with ./create-role.sh. This creates a new stack with the appropriate permissions for the function.

Deploy the lambda function with ./deploy-lambda.sh. Now the function can be used to do nothing :) via a Cloud Formation Custom Resource.

Cloud Formation Usage

Use the function inside your Cloud Formation template by declaring a custom resource, Custom::EchoDependency.

The Custom::EchoDependency takes any parameters and returns them as outputs.

Example Output

{
  "ModifiedDate": "2015-05-20-1433"
}

Extended Example with Stack

"Parameters": {
  "ModifiedDate": {
    "Description": "Date used to force stack update",
    "Type": "String",
    "Default": "never"
  }
},
"Resources": {
  "Echo": {
    "Type": "Custom::EchoDependency",
    "Properties": {
      "ServiceToken": { "Fn::Join": [ "", [
        "arn:aws:lambda:",
        { "Ref": "AWS::Region" },
        ":",
        { "Ref": "AWS::AccountId" },
        ":function:echoDependency"
      ] ] },
      "ModifiedDate": { "Ref": "ModifiedDate" }
    }
  },
  "Outputs": {
    "EchoModifiedDate": {
      "Value": {
        "Fn::GetAtt": [ "Echo", "ModifiedDate" ]
      },
      "Description": "Echo ModifiedDate"
    }
  }
}