From 68428631ccc90f5a973b301c31105b0444f5a8ea Mon Sep 17 00:00:00 2001
From: Gordon Messmer <gordon@dragonsdawn.net>
Date: Thu, 6 Nov 2014 09:51:08 -0800
Subject: Add loader/environment to Jinja2 templates so that files can include
 or extend other files.

---
 .../Bcfg2/Server/Plugins/Cfg/CfgJinja2Generator.py | 45 ++++++++++++++++++++--
 1 file changed, 42 insertions(+), 3 deletions(-)

(limited to 'src/lib')

diff --git a/src/lib/Bcfg2/Server/Plugins/Cfg/CfgJinja2Generator.py b/src/lib/Bcfg2/Server/Plugins/Cfg/CfgJinja2Generator.py
index e36ee78aa..cff9ff61e 100644
--- a/src/lib/Bcfg2/Server/Plugins/Cfg/CfgJinja2Generator.py
+++ b/src/lib/Bcfg2/Server/Plugins/Cfg/CfgJinja2Generator.py
@@ -2,18 +2,26 @@
 <http://jinja.pocoo.org/>`_ templating system to generate
 :ref:`server-plugins-generators-cfg` files. """
 
+import os
+import sys
 import Bcfg2.Options
 from Bcfg2.Server.Plugin import PluginExecutionError, \
     DefaultTemplateDataProvider, get_template_data
 from Bcfg2.Server.Plugins.Cfg import CfgGenerator
 
 try:
-    from jinja2 import Template
+    from jinja2 import Environment, FileSystemLoader
     HAS_JINJA2 = True
 except ImportError:
     HAS_JINJA2 = False
 
 
+class RelEnvironment(Environment):
+    """Override join_path() to enable relative template paths."""
+    def join_path(self, template, parent):
+        return os.path.join(os.path.dirname(parent), template)
+
+
 class DefaultJinja2DataProvider(DefaultTemplateDataProvider):
     """ Template data provider for Jinja2 templates. Jinja2 and
     Genshi currently differ over the value of the ``path`` variable,
@@ -34,6 +42,20 @@ class CfgJinja2Generator(CfgGenerator):
     #: Handle .jinja2 files
     __extensions__ = ['jinja2']
 
+    #: ``__loader_cls__`` is the class that will be instantiated to
+    #: load the template files.  It must implement one public function,
+    #: ``load()``, as :class:`genshi.template.TemplateLoader`.
+    __loader_cls__ = FileSystemLoader
+
+    #: ``__environment_cls__`` is the class that will be instantiated to
+    #: store the jinja2 environment.  It must implement one public function,
+    #: ``get_template()``, as :class:`jinja2.Environment`.
+    __environment_cls__ = RelEnvironment
+
+    #: Ignore ``.jinja2_include`` files so they can be used with the
+    #: Jinja2 ``{% include ... %}`` directive without raising warnings.
+    __ignore__ = ["jinja2_include"]
+
     #: Low priority to avoid matching host- or group-specific
     #: .crypt.jinja2 files
     __priority__ = 50
@@ -42,11 +64,28 @@ class CfgJinja2Generator(CfgGenerator):
         CfgGenerator.__init__(self, fname, spec)
         if not HAS_JINJA2:
             raise PluginExecutionError("Jinja2 is not available")
+        self.template = None
+        encoding = Bcfg2.Options.setup.encoding
+        self.loader = self.__loader_cls__('/',
+                                          encoding=encoding)
+        self.environment = self.__environment_cls__(loader=self.loader)
     __init__.__doc__ = CfgGenerator.__init__.__doc__
 
     def get_data(self, entry, metadata):
-        template = Template(self.data.decode(Bcfg2.Options.setup.encoding))
-        return template.render(
+        if self.template is None:
+            raise PluginExecutionError("Failed to load template %s" %
+                                       self.name)
+        return self.template.render(
             get_template_data(entry, metadata, self.name,
                               default=DefaultJinja2DataProvider()))
     get_data.__doc__ = CfgGenerator.get_data.__doc__
+
+    def handle_event(self, event):
+        CfgGenerator.handle_event(self, event)
+        try:
+            self.template = \
+                self.environment.get_template(self.name)
+        except:
+            raise PluginExecutionError("Failed to load template: %s" %
+                                       sys.exc_info()[1])
+    handle_event.__doc__ = CfgGenerator.handle_event.__doc__
-- 
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