I would like to iterate over a list of values ONLY if the object contains a specific property. Is that possible?

I am receiving the below error.

In our Terraform infrastructure, we generate resources dynamically: a local script is executed and returns a list: something like that:

How to access a resource for output, for exampe ec2 instance: aws_instance.splat_lab.ebs_block_device.*.volume_id
Tried notation module.module-name.path-to-resource, i.e. module.webserver-cas12.aws_instance.splat_lab.ebs_block_device.*.volume_id but module.module-name is empty.

Is it possible to write custom terraform functions?
If yes, how to write them?
Tryied this tutorial but is there no mention of custom terraform functions.

I have two app resources with some common attributes as shown below:

My terraform code is below which deploys certain number of resources based on variable rdsh_count.
I need this resource to deploy conditionally only if variable deploy is set to true, normally I would use count keyword but it’s not going to work here since this resource already have it. How this can be accomplished?

I have resource enable-hibernation which is deployed conditionally and another resource delete-dsc-extension which always needs to run, just in case enable-hibernation exists, it needs to wait for it before starting. How I can use depends_on keyword in delete-dsc-extension resource without erroring in cases where enable-hibernation was never created?

I have a map that looks something like this:

I have a map that looks something like this: