AutoPublishAlias is not triggered for timeout changes

[tdmalone]

Description:

Changing the timeout for a function does not cause a new version to be published when using AutoPublishAlias.

Steps to reproduce:

1. Deploy a SAM template with an AWS::Serverless::Function resource, with AutoPublishAlias set, and specifying any valid value for Timeout.
2. Change the Timeout value to another valid value, and redeploy.

Observed result:

The Timeout value changes on $LATEST, but a new version is not created.

Expected result:

A new version to be created, with the updated configuration.

See also

Similar to #1305, in particular note #1305 (comment) which implies that relevant properties could be added to the hash used to determine if a new version is needed.

[mildaniel]

Hey @tdmalone, thanks for bringing this up. Since resolving this would be considered a backwards incompatible change, we are considering this as a candidate for when we version bump SAM.

[hoffa]

There's been a few similar requests (e.g. #413). We can't update the most straightforward way as it would be a backward incompatible change (would cause many redeployments).

We could however consider an opt-in approach. Something like this (just rough idea):

MyFunction:
  Type: AWS::Serverless::Function
  Properties:
    Timeout: 10
    AutoPublishAlias: live
    AutoPublishAdditionalProperties:
      - Timeout
    ...

[hoffa]

I'll close this in favor of #413.