82 lines
3.1 KiB
Python
82 lines
3.1 KiB
Python
# Copyright 2014-2015 Canonical Limited.
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#
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# This file is part of charm-helpers.
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#
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# charm-helpers is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Lesser General Public License version 3 as
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# published by the Free Software Foundation.
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#
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# charm-helpers is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public License
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# along with charm-helpers. If not, see <http://www.gnu.org/licenses/>.
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import os
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from charmhelpers.core import host
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from charmhelpers.core import hookenv
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def render(source, target, context, owner='root', group='root',
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perms=0o444, templates_dir=None, encoding='UTF-8', template_loader=None):
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"""
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Render a template.
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The `source` path, if not absolute, is relative to the `templates_dir`.
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The `target` path should be absolute. It can also be `None`, in which
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case no file will be written.
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The context should be a dict containing the values to be replaced in the
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template.
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The `owner`, `group`, and `perms` options will be passed to `write_file`.
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If omitted, `templates_dir` defaults to the `templates` folder in the charm.
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The rendered template will be written to the file as well as being returned
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as a string.
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Note: Using this requires python-jinja2; if it is not installed, calling
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this will attempt to use charmhelpers.fetch.apt_install to install it.
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"""
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try:
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from jinja2 import FileSystemLoader, Environment, exceptions
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except ImportError:
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try:
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from charmhelpers.fetch import apt_install
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except ImportError:
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hookenv.log('Could not import jinja2, and could not import '
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'charmhelpers.fetch to install it',
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level=hookenv.ERROR)
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raise
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apt_install('python-jinja2', fatal=True)
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from jinja2 import FileSystemLoader, Environment, exceptions
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if template_loader:
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template_env = Environment(loader=template_loader)
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else:
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if templates_dir is None:
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templates_dir = os.path.join(hookenv.charm_dir(), 'templates')
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template_env = Environment(loader=FileSystemLoader(templates_dir))
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try:
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source = source
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template = template_env.get_template(source)
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except exceptions.TemplateNotFound as e:
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hookenv.log('Could not load template %s from %s.' %
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(source, templates_dir),
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level=hookenv.ERROR)
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raise e
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content = template.render(context)
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if target is not None:
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target_dir = os.path.dirname(target)
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if not os.path.exists(target_dir):
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# This is a terrible default directory permission, as the file
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# or its siblings will often contain secrets.
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host.mkdir(os.path.dirname(target), owner, group, perms=0o755)
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host.write_file(target, content.encode(encoding), owner, group, perms)
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return content
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