How to create a new version of a Lambda function using CloudFormation?

Question

I'm trying to create a new version of a Lambda function using CloudFormation.

I want to have multiple versions of the same Lambda function so that I can (a) point aliases at different versions - like DEV and PROD - and (b) be able to roll back to an earlier version

This is the definition of my Lambda version:

LambdaVersion:
  Type: AWS::Lambda::Version
  Properties:
    FunctionName:
      Ref: LambdaFunction

A version gets created when running "aws cloudformation create-stack" but the subsequent "aws cloudformation update-stack" commands don't do anything. There are no new Lambda versions created.

I'm trying to get a new version of the Lambda function created after I upload new zip file to S3 and then run "update-stack". Can I do it with CloudFormation? Is AWS::Lambda::Version really broken (as mentioned here https://github.com/hashicorp/terraform/issues/6067#issuecomment-211708071) or am I just not getting something?

Update 1/11/17 Official reply from Amazon support: "...for any new version to be published you need to define an addition (sic) AWS::Lambda::Version resource..."

AWS CloudFormation/Lambda team, if you're reading this - this is unacceptable. Fix it.

Answer 1

I have a similar use case (needing to use CloudFormation to manage a lambda function to be used @edge in CloudFront, for which a specific lambda function version is always required, not $LATEST) and my searches landed me at this question first, but after a bit more digging I was happy to find there is now native support for automatic lambda versioning with the new AutoPublishAlias feature of the AWS Serverless Application Model (basically an optional extra set of higher-level constructs for your CloudFormation templates).

Announced here: https://github.com/awslabs/serverless-application-model/issues/41#issuecomment-347723981

For details see:

• https://github.com/awslabs/serverless-application-model/blob/master/docs/safe_lambda_deployments.rst#instant-traffic-shifting-using-lambda-aliases
• https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#referencing-lambda-version--alias-resources

Essentially you include AutoPublishAlias in your AWS::Serverless::Function definition:

MyFunction:
  Type: "AWS::Serverless::Function"
  Properties:
    # ...
    AutoPublishAlias: MyAlias

And then elsewhere in the CloudFormation template you can reference the latest published version as !Ref MyFunction.Version (yaml syntax).