Cloudformation LaunchTemplate referencing IamInstanceProfile fails to create - aws-cloudformation

Question

I am trying to create a LaunchTemplate, which references an IamInstanceProfile, in my Cloudformation stack. Here is the code- i have omitted the irrelevant parts:
...
Resources:
ServerLaunchTemplate:
Type: 'AWS::EC2::LaunchTemplate'
Properties:
LaunchTemplateData:
InstanceType: !Ref InstanceType
SecurityGroups:
- !Ref SecGroup
IamInstanceProfile: !Ref ServerProfile
UserData:
...
ServerProfile:
Type: 'AWS::IAM::InstanceProfile'
Properties:
Path: /
Roles:
- !Ref ServerRole
...
The ServerProfile gets created successfully. However when the stack creation process reaches the step of creating the ServerLaunchTemplate, it fails with the error:
Property validation failure: [Value of property {/LaunchTemplateData/IamInstanceProfile} does not match type {Object}]
If i omit the reference to the IamInstanceProfile, the LaunchTemplate get created successfully.
According to the documentation and some examples this should work... Based on the error i understand, that the InstanceType field of the LaunchTemplate needs to reference an object, but "!Ref InstanceType" returns the resource id.
How can i fix this? How could i retrieve the object, that is presumably required by the "/LaunchTemplateData/IamInstanceProfile" field?
Thank you

Answer 1

Easy to miss in the docs: IamInstanceProfile requires an IamInstanceProfile Cloudformation object with the Arn of the referenced IamInstanceProfile being a property of it.
See https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-ec2-launchtemplate-launchtemplatedata.html#cfn-ec2-launchtemplate-launchtemplatedata-iaminstanceprofile and https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-ec2-launchtemplate-iaminstanceprofile.html.
This should work:
PortalLaunchTemplate:
Type: 'AWS::EC2::LaunchTemplate'
Properties:
LaunchTemplateName: !Sub ${InstanceName}-launch-template
LaunchTemplateData:
ImageId: !Ref AmiId
...
IamInstanceProfile:
Arn: !GetAtt InstanceProfile.Arn

Answer 2

What worked for me was:
"IamInstanceProfile":{ "Arn":
{
"Fn::Sub":"arn:aws:iam::${AWS::AccountId}:instanceprofile/${name_of_Instance_profile}"
}
Presumably because it requires the "Arn" value as a string.