sceptre 1.x -> 2.x conversion for a custom resolver

[himmelmrm]

python newbie here ...

I inherited a sceptre 1.x repo that I am converting to sceptre 2.x.
The 1.x repo has a custom resolver that accepts a jinja formatted file for AWS instance user data.

Here's the original:
"file_as_template.py"

from sceptre.resolvers import Resolver
from jinja2 import Template

class FileAsTemplate(Resolver):

    def __init__(self, *args, **kwargs):
        super(FileAsTemplate, self).__init__(*args, **kwargs)

    def resolve(self):
        try:
            with open(self.argument, "r") as file:
                data = file.read()
                template = Template(data)
                template_data = self.stack_config['template_data']
                return template.render(**template_data)
        except (EnvironmentError, TypeError) as e:
            raise e

The above throws :

AttributeError: 'FileAsTemplate' object has no attribute 'stack_config'

Assuming that hooks and resolvers are similar, I tried to apply learnings from #684 but I'm not having any success.

JIC it matters, here's my setup.py:

from setuptools import setup

setup(
    name='file-as-template-resolver',
    py_modules=['file_as_template'],
    entry_points={
        'sceptre.resolvers': [
            'file_as_template = file_as_template:FileAsTemplate',
        ],
    }
)

Any assistance would be greatly appreciated.

[zaro0508]

I think you are referring to the https://github.com/lukeplausin/sceptre-template-resolver @himmelmrm? if so i think the new sceptre-file-resolver can accomplish the same use case and it's included in sceptre ver 2.6.1

[himmelmrm]

Thanks for the reply.
Custom resolver "file_as_template" was created to allow EC2 userdata to be templatized. It's used like this in a troposphere template:

template_path: ec2/instances.py
template_data:
  cloudinit_data:
   hostname: prod-lampdemo-aws01
   fqdn: prod-lampdemo-aws01.demo.client.com
sceptre_user_data:
  UserData: !file_as_template config/lampdemo/prod/ud-combined.j2

[himmelmrm]

I think I get what you are saying about sceptre-file-resolver -- it understands jinja if I use .j2 as the extension for the input file?

[himmelmrm]

It seems that https://github.com/lukeplausin/sceptre-template-resolver accepts Jinja2 (.j2) templates, but the new core sceptre-file-resolver does not. Am I understanding correctly?

[zaro0508]

ahh you are correct @himmelmrm, i misunderstood the purpose of the sceptre-template-resolver. if self.stack_config['template_data'] doesn't work anymore i would try self.stack.template then reference the template class member you need, https://github.com/Sceptre/sceptre/blob/master/sceptre/template.py#L55

[himmelmrm]

Thanks for pointing me in the right direction -- this works:
template_data = self.stack.template.sceptre_user_data