feat(aws-autoscaling): Support a external LaunchConfiguration and LaunchTemplate to AutoScalingGroup

[cohalz]

Fixed #1403

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[eladb]

@cohalz this is awesome, but we generally avoid "leaking" the Cfn classes in the API of AWS constructs. Granted, this is a large surface area to cover, but also an opportunity to actually provide a lot of value to users.

As a workaround, users can use property overrides, so I hope you are not blocked by this.

Let me know if you wish to take this to the next level. It's not a small project, I am aware 😄

[cohalz]

@eladb thanks, I understand constructs.

I want to use ECS Construct Library with spot instances, but AutoScalingGroup does not support LaunchTemplate. Also, InstanceDrainHook does not exported, so I need to describe too long Resources to construct cluster.

So, I added #1392 and this PR.

[cohalz]

I tried this code.

const asgResource = asg.findChild('ASG') as autoscaling.cloudformation.AutoScalingGroupResource

asgResource.addPropertyDeletionOverride('LaunchConfigurationName')
asgResource.addPropertyOverride('LaunchTemplate', {
  LaunchTemplateId: appLaunchTemplate.ref,
  Version: '1'
})

It's working, but AWS::AutoScaling::LaunchConfiguration will be created uselessly.

[eladb]

It's working, but AWS::AutoScaling::LaunchConfiguration will be created uselessly.

This actually brings up a missing feature in our "escape hatching" mechanism. You want to be able to delete an entire resource from a subtree. Raised #1408

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If your current use case is to only be able to pass in a LaunchTemplateId to the ASG, how about we repurpose this PR to only add an optional property to the ASG props LaunchTemplateId: string and LaunchTemplateVersion: string. Then, if LaunchTemplateId is passed, a LaunchConfiguration won't be created and the ID (+ version) will be configured instead.

Would that make sense?

[rix0rrr]

I agree we should either limit the scope of this change, or implement a proper Launch Configuration construct.

[eladb]

@cohalz closing for now. Feel free to reopen when/if you wish to continue this work.

[LeifW]

Would this be worth revisiting now that we have #12385 ?