charm-plumgrid-gateway/hooks/charmhelpers/contrib/hardening/templating.py

72 lines
2.4 KiB
Python

# Copyright 2016 Canonical Limited.
#
# This file is part of charm-helpers.
#
# charm-helpers is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License version 3 as
# published by the Free Software Foundation.
#
# charm-helpers is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with charm-helpers. If not, see <http://www.gnu.org/licenses/>.
import os
from charmhelpers.core.hookenv import (
log,
DEBUG,
WARNING,
)
try:
from jinja2 import FileSystemLoader, Environment
except ImportError:
from charmhelpers.fetch import apt_install
from charmhelpers.fetch import apt_update
apt_update(fatal=True)
apt_install('python-jinja2', fatal=True)
from jinja2 import FileSystemLoader, Environment
# NOTE: function separated from main rendering code to facilitate easier
# mocking in unit tests.
def write(path, data):
with open(path, 'wb') as out:
out.write(data)
def get_template_path(template_dir, path):
"""Returns the template file which would be used to render the path.
The path to the template file is returned.
:param template_dir: the directory the templates are located in
:param path: the file path to be written to.
:returns: path to the template file
"""
return os.path.join(template_dir, os.path.basename(path))
def render_and_write(template_dir, path, context):
"""Renders the specified template into the file.
:param template_dir: the directory to load the template from
:param path: the path to write the templated contents to
:param context: the parameters to pass to the rendering engine
"""
env = Environment(loader=FileSystemLoader(template_dir))
template_file = os.path.basename(path)
template = env.get_template(template_file)
log('Rendering from template: %s' % template.name, level=DEBUG)
rendered_content = template.render(context)
if not rendered_content:
log("Render returned None - skipping '%s'" % path,
level=WARNING)
return
write(path, rendered_content.encode('utf-8').strip())
log('Wrote template %s' % path, level=DEBUG)