Source code for sceptre.template_handlers.helper

import logging
import os
import sys
import traceback

from importlib.machinery import SourceFileLoader
from jinja2 import Environment, select_autoescape, FileSystemLoader, StrictUndefined
from pathlib import Path
from sceptre.exceptions import TemplateSceptreHandlerError, TemplateNotFoundError
from sceptre.config import strategies

logger = logging.getLogger(__name__)

"""
Template handler helpers.
"""


[docs]def call_sceptre_handler(path, sceptre_user_data): """ Calls the function `sceptre_handler` within templates that are python scripts. :param path: A path to the file. :type name: str :param sceptre_user_data: The sceptre_user_data parameter values. :type name: str :returns: The string returned from sceptre_handler in the template. :rtype: str :raises: IOError :raises: TemplateSceptreHandlerError """ # Get relative path as list between current working directory and where # the template is # NB: this is a horrible hack... relpath = os.path.relpath(path, os.getcwd()).split(os.path.sep) relpaths_to_add = [ os.path.sep.join(relpath[:i + 1]) for i in range(len(relpath[:-1])) ] # Add any directory between the current working directory and where # the template is to the python path for directory in relpaths_to_add: sys.path.append(os.path.join(os.getcwd(), directory)) logger.debug( "Getting CloudFormation from %s", path ) if not os.path.isfile(path): raise TemplateNotFoundError("No such template file: '%s'", path) module = SourceFileLoader(path, path).load_module() try: body = module.sceptre_handler(sceptre_user_data) except AttributeError as e: if 'sceptre_handler' in str(e): raise TemplateSceptreHandlerError( "The template does not have the required " "'sceptre_handler(sceptre_user_data)' function." ) else: raise e for directory in relpaths_to_add: sys.path.remove(os.path.join(os.getcwd(), directory)) return body
[docs]def render_jinja_template(path, jinja_vars, j2_environment): """ Renders a jinja template. Sceptre supports passing sceptre_user_data to JSON and YAML CloudFormation templates using Jinja2 templating. :param path: The path to the template file. :type path: str :param jinja_vars: Dict of variables to render into the template. :type jinja_vars: dict :param j2_environment: The jinja2 environment. :type stack_group_config: dict :returns: The body of the CloudFormation template. :rtype: str """ path = Path(path) if not path.exists(): raise TemplateNotFoundError("No such template file: '%s'", path) logger.debug("%s Rendering CloudFormation template", path) default_j2_environment_config = { "autoescape": select_autoescape( disabled_extensions=('j2',), default=True, ), "loader": FileSystemLoader(path.parent), "undefined": StrictUndefined } j2_environment_config = strategies.dict_merge( default_j2_environment_config, j2_environment ) j2_environment = Environment(**j2_environment_config) template = j2_environment.get_template(path.name) body = template.render(**jinja_vars) return body