Reference stack_name from stack config

[zaro0508]

I have a jinja template and would like to pass the stack_name to the template. The only way to do this is to pass it in with a sceptre_user_data key. Since it's already defined in each stack config it would be nice to be able to reference the stack_name instead of having to define multiple times. This also applies to passing it to any plugin like hooks and parameters.

This works template/test/noop.yaml:

template_path: mystack.j2
stack_name: noop
sceptre_user_data:
  stackname: noop 
parameters:
  stackname: noop
hooks
  after_create:
    -  !cmd "python noop.py"  

However this would be much better template/test/noop.yaml

template_path: mystack.j2
stack_name: noop
sceptre_user_data:
  stackname: {{ stack_config.stack_name }} 
parameters:
  stackname: {{ stack_config.stack_name }}
hooks
  after_create:
    -  !cmd "python {{ stack_config.stack_name }}.py"  

[zaro0508]

related to issue #355

[zaro0508]

My workaround for this issue is to create the sceptre-identity-resolver

[zaro0508]

I didn't realize an important fact that all sceptre files are read in as jinja templates which means an even better workaround for this is to just use jinja

{% set StackName = "MyStack" %}
template_path: ec2.yaml
stack_name: {{ StackName }}
parameters:
  StackName: {{ StackName }}
sceptre_user_data:
  StackName: {{ StackName }}
hooks
  after_create:
    -  !cmd "python {{ StackName }}.py"