How to use Sub and GetAtt functions at the same time in CloudFormation template?

Question

I create CloudFormation yaml template and I need to use !GetAtt \"TestLambda.Arn\" as part of !Sub function in \"AWS::ApiGateway::Method\" Integrat

Answer 1

You don't need to use !GetAtt here, !Sub will automatically unpack values for you if you place them within the place holder:

Uri: !Sub arn:aws:apigateway:us-east-1:lambda:path/2015-03-31/functions/${TestLambda.Arn}/invocations

This is explained in the docs:

If you specify template parameter names or resource logical IDs, such as ${InstanceTypeParameter}, AWS CloudFormation returns the same values as if you used the Ref intrinsic function. If you specify resource attributes, such as ${MyInstance.PublicIp}, AWS CloudFormation returns the same values as if you used the Fn::GetAtt intrinsic function.