charm-cinder/hooks/charmhelpers/core/templating.py
2015-02-24 11:02:48 +00:00

69 lines
2.5 KiB
Python

# Copyright 2014-2015 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 import host
from charmhelpers.core import hookenv
def render(source, target, context, owner='root', group='root',
perms=0o444, templates_dir=None, encoding='UTF-8'):
"""
Render a template.
The `source` path, if not absolute, is relative to the `templates_dir`.
The `target` path should be absolute.
The context should be a dict containing the values to be replaced in the
template.
The `owner`, `group`, and `perms` options will be passed to `write_file`.
If omitted, `templates_dir` defaults to the `templates` folder in the charm.
Note: Using this requires python-jinja2; if it is not installed, calling
this will attempt to use charmhelpers.fetch.apt_install to install it.
"""
try:
from jinja2 import FileSystemLoader, Environment, exceptions
except ImportError:
try:
from charmhelpers.fetch import apt_install
except ImportError:
hookenv.log('Could not import jinja2, and could not import '
'charmhelpers.fetch to install it',
level=hookenv.ERROR)
raise
apt_install('python-jinja2', fatal=True)
from jinja2 import FileSystemLoader, Environment, exceptions
if templates_dir is None:
templates_dir = os.path.join(hookenv.charm_dir(), 'templates')
loader = Environment(loader=FileSystemLoader(templates_dir))
try:
source = source
template = loader.get_template(source)
except exceptions.TemplateNotFound as e:
hookenv.log('Could not load template %s from %s.' %
(source, templates_dir),
level=hookenv.ERROR)
raise e
content = template.render(context)
host.mkdir(os.path.dirname(target), owner, group, perms=0o755)
host.write_file(target, content.encode(encoding), owner, group, perms)