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Diffstat (limited to 'charms/trusty/ceilometer-agent/hooks/charmhelpers/contrib/openstack/templating.py')
| -rw-r--r-- | charms/trusty/ceilometer-agent/hooks/charmhelpers/contrib/openstack/templating.py | 321 |
1 files changed, 321 insertions, 0 deletions
diff --git a/charms/trusty/ceilometer-agent/hooks/charmhelpers/contrib/openstack/templating.py b/charms/trusty/ceilometer-agent/hooks/charmhelpers/contrib/openstack/templating.py new file mode 100644 index 0000000..8958895 --- /dev/null +++ b/charms/trusty/ceilometer-agent/hooks/charmhelpers/contrib/openstack/templating.py @@ -0,0 +1,321 @@ +# Copyright 2014-2015 Canonical Limited. +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +import os + +import six + +from charmhelpers.fetch import apt_install, apt_update +from charmhelpers.core.hookenv import ( + log, + ERROR, + INFO +) +from charmhelpers.contrib.openstack.utils import OPENSTACK_CODENAMES + +try: + from jinja2 import FileSystemLoader, ChoiceLoader, Environment, exceptions +except ImportError: + apt_update(fatal=True) + apt_install('python-jinja2', fatal=True) + from jinja2 import FileSystemLoader, ChoiceLoader, Environment, exceptions + + +class OSConfigException(Exception): + pass + + +def get_loader(templates_dir, os_release): + """ + Create a jinja2.ChoiceLoader containing template dirs up to + and including os_release. If directory template directory + is missing at templates_dir, it will be omitted from the loader. + templates_dir is added to the bottom of the search list as a base + loading dir. + + A charm may also ship a templates dir with this module + and it will be appended to the bottom of the search list, eg:: + + hooks/charmhelpers/contrib/openstack/templates + + :param templates_dir (str): Base template directory containing release + sub-directories. + :param os_release (str): OpenStack release codename to construct template + loader. + :returns: jinja2.ChoiceLoader constructed with a list of + jinja2.FilesystemLoaders, ordered in descending + order by OpenStack release. + """ + tmpl_dirs = [(rel, os.path.join(templates_dir, rel)) + for rel in six.itervalues(OPENSTACK_CODENAMES)] + + if not os.path.isdir(templates_dir): + log('Templates directory not found @ %s.' % templates_dir, + level=ERROR) + raise OSConfigException + + # the bottom contains tempaltes_dir and possibly a common templates dir + # shipped with the helper. + loaders = [FileSystemLoader(templates_dir)] + helper_templates = os.path.join(os.path.dirname(__file__), 'templates') + if os.path.isdir(helper_templates): + loaders.append(FileSystemLoader(helper_templates)) + + for rel, tmpl_dir in tmpl_dirs: + if os.path.isdir(tmpl_dir): + loaders.insert(0, FileSystemLoader(tmpl_dir)) + if rel == os_release: + break + log('Creating choice loader with dirs: %s' % + [l.searchpath for l in loaders], level=INFO) + return ChoiceLoader(loaders) + + +class OSConfigTemplate(object): + """ + Associates a config file template with a list of context generators. + Responsible for constructing a template context based on those generators. + """ + def __init__(self, config_file, contexts): + self.config_file = config_file + + if hasattr(contexts, '__call__'): + self.contexts = [contexts] + else: + self.contexts = contexts + + self._complete_contexts = [] + + def context(self): + ctxt = {} + for context in self.contexts: + _ctxt = context() + if _ctxt: + ctxt.update(_ctxt) + # track interfaces for every complete context. + [self._complete_contexts.append(interface) + for interface in context.interfaces + if interface not in self._complete_contexts] + return ctxt + + def complete_contexts(self): + ''' + Return a list of interfaces that have satisfied contexts. + ''' + if self._complete_contexts: + return self._complete_contexts + self.context() + return self._complete_contexts + + +class OSConfigRenderer(object): + """ + This class provides a common templating system to be used by OpenStack + charms. It is intended to help charms share common code and templates, + and ease the burden of managing config templates across multiple OpenStack + releases. + + Basic usage:: + + # import some common context generates from charmhelpers + from charmhelpers.contrib.openstack import context + + # Create a renderer object for a specific OS release. + configs = OSConfigRenderer(templates_dir='/tmp/templates', + openstack_release='folsom') + # register some config files with context generators. + configs.register(config_file='/etc/nova/nova.conf', + contexts=[context.SharedDBContext(), + context.AMQPContext()]) + configs.register(config_file='/etc/nova/api-paste.ini', + contexts=[context.IdentityServiceContext()]) + configs.register(config_file='/etc/haproxy/haproxy.conf', + contexts=[context.HAProxyContext()]) + # write out a single config + configs.write('/etc/nova/nova.conf') + # write out all registered configs + configs.write_all() + + **OpenStack Releases and template loading** + + When the object is instantiated, it is associated with a specific OS + release. This dictates how the template loader will be constructed. + + The constructed loader attempts to load the template from several places + in the following order: + - from the most recent OS release-specific template dir (if one exists) + - the base templates_dir + - a template directory shipped in the charm with this helper file. + + For the example above, '/tmp/templates' contains the following structure:: + + /tmp/templates/nova.conf + /tmp/templates/api-paste.ini + /tmp/templates/grizzly/api-paste.ini + /tmp/templates/havana/api-paste.ini + + Since it was registered with the grizzly release, it first seraches + the grizzly directory for nova.conf, then the templates dir. + + When writing api-paste.ini, it will find the template in the grizzly + directory. + + If the object were created with folsom, it would fall back to the + base templates dir for its api-paste.ini template. + + This system should help manage changes in config files through + openstack releases, allowing charms to fall back to the most recently + updated config template for a given release + + The haproxy.conf, since it is not shipped in the templates dir, will + be loaded from the module directory's template directory, eg + $CHARM/hooks/charmhelpers/contrib/openstack/templates. This allows + us to ship common templates (haproxy, apache) with the helpers. + + **Context generators** + + Context generators are used to generate template contexts during hook + execution. Doing so may require inspecting service relations, charm + config, etc. When registered, a config file is associated with a list + of generators. When a template is rendered and written, all context + generates are called in a chain to generate the context dictionary + passed to the jinja2 template. See context.py for more info. + """ + def __init__(self, templates_dir, openstack_release): + if not os.path.isdir(templates_dir): + log('Could not locate templates dir %s' % templates_dir, + level=ERROR) + raise OSConfigException + + self.templates_dir = templates_dir + self.openstack_release = openstack_release + self.templates = {} + self._tmpl_env = None + + if None in [Environment, ChoiceLoader, FileSystemLoader]: + # if this code is running, the object is created pre-install hook. + # jinja2 shouldn't get touched until the module is reloaded on next + # hook execution, with proper jinja2 bits successfully imported. + apt_install('python-jinja2') + + def register(self, config_file, contexts): + """ + Register a config file with a list of context generators to be called + during rendering. + """ + self.templates[config_file] = OSConfigTemplate(config_file=config_file, + contexts=contexts) + log('Registered config file: %s' % config_file, level=INFO) + + def _get_tmpl_env(self): + if not self._tmpl_env: + loader = get_loader(self.templates_dir, self.openstack_release) + self._tmpl_env = Environment(loader=loader) + + def _get_template(self, template): + self._get_tmpl_env() + template = self._tmpl_env.get_template(template) + log('Loaded template from %s' % template.filename, level=INFO) + return template + + def render(self, config_file): + if config_file not in self.templates: + log('Config not registered: %s' % config_file, level=ERROR) + raise OSConfigException + ctxt = self.templates[config_file].context() + + _tmpl = os.path.basename(config_file) + try: + template = self._get_template(_tmpl) + except exceptions.TemplateNotFound: + # if no template is found with basename, try looking for it + # using a munged full path, eg: + # /etc/apache2/apache2.conf -> etc_apache2_apache2.conf + _tmpl = '_'.join(config_file.split('/')[1:]) + try: + template = self._get_template(_tmpl) + except exceptions.TemplateNotFound as e: + log('Could not load template from %s by %s or %s.' % + (self.templates_dir, os.path.basename(config_file), _tmpl), + level=ERROR) + raise e + + log('Rendering from template: %s' % _tmpl, level=INFO) + return template.render(ctxt) + + def write(self, config_file): + """ + Write a single config file, raises if config file is not registered. + """ + if config_file not in self.templates: + log('Config not registered: %s' % config_file, level=ERROR) + raise OSConfigException + + _out = self.render(config_file) + + with open(config_file, 'wb') as out: + out.write(_out) + + log('Wrote template %s.' % config_file, level=INFO) + + def write_all(self): + """ + Write out all registered config files. + """ + [self.write(k) for k in six.iterkeys(self.templates)] + + def set_release(self, openstack_release): + """ + Resets the template environment and generates a new template loader + based on a the new openstack release. + """ + self._tmpl_env = None + self.openstack_release = openstack_release + self._get_tmpl_env() + + def complete_contexts(self): + ''' + Returns a list of context interfaces that yield a complete context. + ''' + interfaces = [] + [interfaces.extend(i.complete_contexts()) + for i in six.itervalues(self.templates)] + return interfaces + + def get_incomplete_context_data(self, interfaces): + ''' + Return dictionary of relation status of interfaces and any missing + required context data. Example: + {'amqp': {'missing_data': ['rabbitmq_password'], 'related': True}, + 'zeromq-configuration': {'related': False}} + ''' + incomplete_context_data = {} + + for i in six.itervalues(self.templates): + for context in i.contexts: + for interface in interfaces: + related = False + if interface in context.interfaces: + related = context.get_related() + missing_data = context.missing_data + if missing_data: + incomplete_context_data[interface] = {'missing_data': missing_data} + if related: + if incomplete_context_data.get(interface): + incomplete_context_data[interface].update({'related': True}) + else: + incomplete_context_data[interface] = {'related': True} + else: + incomplete_context_data[interface] = {'related': False} + return incomplete_context_data |