diff options
| -rw-r--r-- | python/vyos/template.py | 163 |
1 files changed, 108 insertions, 55 deletions
diff --git a/python/vyos/template.py b/python/vyos/template.py index d9b0c749d..c88ab04a0 100644 --- a/python/vyos/template.py +++ b/python/vyos/template.py @@ -1,4 +1,4 @@ -# Copyright 2019 VyOS maintainers and contributors <maintainers@vyos.io> +# Copyright 2019-2020 VyOS maintainers and contributors <maintainers@vyos.io> # # This library is free software; you can redistribute it and/or # modify it under the terms of the GNU Lesser General Public @@ -13,78 +13,131 @@ # You should have received a copy of the GNU Lesser General Public # License along with this library. If not, see <http://www.gnu.org/licenses/>. +import functools import os +from ipaddress import ip_network from jinja2 import Environment from jinja2 import FileSystemLoader from vyos.defaults import directories from vyos.util import chmod, chown, makedir -# reuse the same Environment to improve performance -_templates_env = { - False: Environment(loader=FileSystemLoader(directories['templates'])), - True: Environment(loader=FileSystemLoader(directories['templates']), trim_blocks=True), -} -_templates_mem = { - False: {}, - True: {}, -} -def vyos_address_from_cidr(text): - """ Take an IPv4/IPv6 CIDR prefix and convert the network to an "address". - Example: - 192.0.2.0/24 -> 192.0.2.0, 2001:db8::/48 -> 2001:db8:: - """ - from ipaddress import ip_network - return ip_network(text).network_address +# Holds template filters registered via register_filter() +_FILTERS = {} -def vyos_netmask_from_cidr(text): - """ Take an IPv4/IPv6 CIDR prefix and convert the prefix length to a "subnet mask". - Example: - 192.0.2.0/24 -> 255.255.255.0, 2001:db8::/48 -> ffff:ffff:ffff:: - """ - from ipaddress import ip_network - return ip_network(text).netmask -def render(destination, template, content, trim_blocks=False, formater=None, permission=None, user=None, group=None): +# reuse Environments with identical trim_blocks setting to improve performance +@functools.lru_cache(maxsize=2) +def _get_environment(trim_blocks): + env = Environment( + # Don't check if template files were modified upon re-rendering + auto_reload=False, + # Cache up to this number of templates for quick re-rendering + cache_size=100, + loader=FileSystemLoader(directories["templates"]), + trim_blocks=trim_blocks, + ) + env.filters.update(_FILTERS) + return env + + +def register_filter(name, func=None): + """Register a function to be available as filter in templates under given name. + + It can also be used as a decorator, see below in this module for examples. + + :raise RuntimeError: + when trying to register a filter after a template has been rendered already + :raise ValueError: when trying to register a name which was taken already """ - render a template from the template directory, it will raise on any errors - destination: the file where the rendered template must be saved - template: the path to the template relative to the template folder - content: the dictionary to use to render the template - - This classes cache the renderer, so rendering the same file multiple time - does not cause as too much overhead. If use everywhere, it could be changed - and load the template from python environement variables from an import - python module generated when the debian package is build - (recovering the load time and overhead caused by having the file out of the code) + if func is None: + return functools.partial(register_filter, name) + if _get_environment.cache_info().currsize: + raise RuntimeError( + "Filters can only be registered before rendering the first template" + ) + if name in _FILTERS: + raise ValueError(f"A filter with name {name!r} was registered already") + _FILTERS[name] = func + return func + + +def render_to_string(template, content, trim_blocks=False, formater=None): + """Render a template from the template directory, raise on any errors. + + :param template: the path to the template relative to the template folder + :param content: the dictionary of variables to put into rendering context + :param trim_blocks: controls the trim_blocks jinja2 feature + :param formater: + if given, it has to be a callable the rendered string is passed through + + The parsed template files are cached, so rendering the same file multiple times + does not cause as too much overhead. + If used everywhere, it could be changed to load the template from Python + environment variables from an importable Python module generated when the Debian + package is build (recovering the load time and overhead caused by having the + file out of the code). """ + template = _get_environment(bool(trim_blocks)).get_template(template) + rendered = template.render(content) + if formater is not None: + rendered = formater(rendered) + return rendered + + +def render( + destination, + template, + content, + trim_blocks=False, + formater=None, + permission=None, + user=None, + group=None, +): + """Render a template from the template directory to a file, raise on any errors. - # Create the directory if it does not exists + :param destination: path to the file to save the rendered template in + :param permission: permission bitmask to set for the output file + :param user: user to own the output file + :param group: group to own the output file + + All other parameters are as for :func:`render_to_string`. + """ + # Create the directory if it does not exist folder = os.path.dirname(destination) makedir(folder, user, group) - # Setup a renderer for the given template - # This is cached and re-used for performance - if template not in _templates_mem[trim_blocks]: - _env = _templates_env[trim_blocks] - _env.filters['address_from_cidr'] = vyos_address_from_cidr - _env.filters['netmask_from_cidr'] = vyos_netmask_from_cidr - _templates_mem[trim_blocks][template] = _env.get_template(template) + # As we are opening the file with 'w', we are performing the rendering before + # calling open() to not accidentally erase the file if rendering fails + rendered = render_to_string(template, content, trim_blocks, formater) - template = _templates_mem[trim_blocks][template] + # Write to file + with open(destination, "w") as file: + chmod(file.fileno(), permission) + chown(file.fileno(), user, group) + file.write(rendered) - # As we are opening the file with 'w', we are performing the rendering - # before calling open() to not accidentally erase the file if the - # templating fails - content = template.render(content) - if formater: - content = formater(content) +################################## +# Custom template filters follow # +################################## - # Write client config file - with open(destination, 'w') as f: - f.write(content) - chmod(destination, permission) - chown(destination, user, group) +@register_filter("address_from_cidr") +def vyos_address_from_cidr(text): + """ Take an IPv4/IPv6 CIDR prefix and convert the network to an "address". + Example: + 192.0.2.0/24 -> 192.0.2.0, 2001:db8::/48 -> 2001:db8:: + """ + return ip_network(text).network_address + + +@register_filter("netmask_from_cidr") +def vyos_netmask_from_cidr(text): + """ Take an IPv4/IPv6 CIDR prefix and convert the prefix length to a "subnet mask". + Example: + 192.0.2.0/24 -> 255.255.255.0, 2001:db8::/48 -> ffff:ffff:ffff:: + """ + return ip_network(text).netmask |