Model Lambda's Alias.updatePolicy in our AWS::Lambda::Alias L1

[skinny85]

Some CloudFormation resources (the example I know is AWS::Lambda::Alias with its UpdatePolicy) have attributes that are not listed under the Properties key in a template. These are currently not available in our L1s.

They need to be added if we want to model these in the CDK.

[eladb]

Technically you should be able to use updatePolicy but the Alias update policy schema is not available there at the moment:

myResource.options.updatePolicy = {
  autoScalingReplacingUpdate: {
    willReplace: true
  }
}

Maybe we should convert this issue? And also add L2 support?

[skinny85]

Fair enough - I changed the title of the issue.

L2 support is exactly why I'm opening this issue - because I want to add it :).

[rix0rrr]

This is where it's happening for ASGs:

https://github.com/awslabs/aws-cdk/blob/master/packages/@aws-cdk/aws-autoscaling/lib/auto-scaling-group.ts#L433

[rix0rrr]

L1 creation/update policies are not generated but hand-written, so it should be easy enough to add the appropriate policies for Alias:

https://github.com/awslabs/aws-cdk/blob/master/packages/@aws-cdk/cdk/lib/cloudformation/resource-policy.ts

[skinny85]

@rix0rrr but how to change the type of the UpdatePolicy in the Lambda alias L1? Right now, it's the same UpdatePolicy that's used in auto-scaling groups, and it's set in the Resource class itself.

How to go about changing the type of updatePolicy for AliasResource?

[rix0rrr]

You don't, but you can just make the one UpdatePolicy type the union of all possible updatepolicy configurations. That is, you would add a CodeDeployLambdaAliasUpdate field to the current UpdatePolicy type.

That is how CloudFormation "thinks" about it as well. They don't have an UpdatePolicy per resource type page. Instead, they have a single UpdatePolicy page with all possible configurations under it:

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-attribute-updatepolicy.html