ceph/src/pybind/mgr/cephadm/template.py

   1 import copy
   2 from typing import Optional
   3
   4 from jinja2 import Environment, PackageLoader, select_autoescape, StrictUndefined
   5 from jinja2 import exceptions as j2_exceptions
   6
   7
   8 class TemplateError(Exception):
   9     pass
  10
  11
  12 class UndefinedError(TemplateError):
  13     pass
  14
  15
  16 class TemplateNotFoundError(TemplateError):
  17     pass
  18
  19
  20 class TemplateEngine:
  21     def render(self, name: str, context: Optional[dict] = None) -> str:
  22         raise NotImplementedError()
  23
  24
  25 class Jinja2Engine(TemplateEngine):
  26     def __init__(self):
  27         self.env = Environment(
  28             loader=PackageLoader('cephadm', 'templates'),
  29             autoescape=select_autoescape(['html', 'xml']),
  30             trim_blocks=True,
  31             lstrip_blocks=True,
  32             undefined=StrictUndefined
  33         )
  34
  35     def render(self, name: str, context: Optional[dict] = None) -> str:
  36         try:
  37             template = self.env.get_template(name)
  38             if context is None:
  39                 return template.render()
  40             return template.render(context)
  41         except j2_exceptions.UndefinedError as e:
  42             raise UndefinedError(e.message)
  43         except j2_exceptions.TemplateNotFound as e:
  44             raise TemplateNotFoundError(e.message)
  45
  46
  47 class TemplateMgr:
  48     def __init__(self):
  49         self.engine = Jinja2Engine()
  50         self.base_context = {
  51             'cephadm_managed': 'This file is generated by cephadm.'
  52         }
  53
  54     def render(self, name: str, context: Optional[dict] = None, managed_context=True) -> str:
  55         """Render a string from a template with context.
  56
  57         :param name: template name. e.g. services/nfs/ganesha.conf.j2
  58         :type name: str
  59         :param context: a dictionary that contains values to be used in the template, defaults
  60             to None
  61         :type context: Optional[dict], optional
  62         :param managed_context: to inject default context like managed header or not, defaults
  63             to True
  64         :type managed_context: bool, optional
  65         :return: the templated string
  66         :rtype: str
  67         """
  68         ctx = {}
  69         if managed_context:
  70             ctx = copy.deepcopy(self.base_context)
  71         if context is not None:
  72             ctx = {**ctx, **context}
  73         return self.engine.render(name, ctx)