from functools import partial from django.db.models.loading import get_model from django.utils import timezone from django.utils.functional import cached_property from django.utils.translation import ugettext_lazy as _ from orchestra.apps import plugins from . import methods class ServiceBackend(plugins.Plugin): """ Service management backend base class It uses the _unit of work_ design principle, which allows bulk operations to be conviniently supported. Each backend generates the configuration for all the changes of all modified objects, reloading the daemon just once. """ model = None related_models = () # ((model, accessor__attribute),) script_method = methods.SSH script_executable = '/bin/bash' function_method = methods.Python type = 'task' # 'sync' ignore_fields = [] actions = [] __metaclass__ = plugins.PluginMount def __unicode__(self): return type(self).__name__ def __str__(self): return unicode(self) def __init__(self): self.head = [] self.content = [] self.tail = [] def __getattribute__(self, attr): """ Select head, content or tail section depending on the method name """ IGNORE_ATTRS = ( 'append', 'cmd_section', 'head', 'tail', 'content', 'script_method', 'function_method' ) if attr == 'prepare': self.cmd_section = self.head elif attr == 'commit': self.cmd_section = self.tail elif attr not in IGNORE_ATTRS: self.cmd_section = self.content return super(ServiceBackend, self).__getattribute__(attr) @classmethod def get_actions(cls): return [ action for action in cls.actions if action in dir(cls) ] @classmethod def get_name(cls): return cls.__name__ @classmethod def is_main(cls, obj): opts = obj._meta return cls.model == '%s.%s' % (opts.app_label, opts.object_name) @classmethod def get_related(cls, obj): opts = obj._meta model = '%s.%s' % (opts.app_label, opts.object_name) for rel_model, field in cls.related_models: if rel_model == model: related = obj for attribute in field.split('__'): related = getattr(related, attribute) return related return None @classmethod def get_backends(cls, instance=None, action=None): backends = cls.get_plugins() included = [] # Filter for instance or action if instance or action: for backend in backends: include = True if instance: opts = instance._meta if backend.model != '.'.join((opts.app_label, opts.object_name)): include = False if include and action: if action not in backend.get_actions(): include = False if include: included.append(backend) backends = included return backends @classmethod def get_backend(cls, name): return cls.get_plugin(name) @classmethod def model_class(cls): return get_model(cls.model) @property def scripts(self): """ group commands based on their method """ if not self.content: return [] scripts = {} for method, cmd in self.content: scripts[method] = [] for method, commands in self.head + self.content + self.tail: try: scripts[method] += commands except KeyError: pass return list(scripts.iteritems()) def get_banner(self): time = timezone.now().strftime("%h %d, %Y %I:%M:%S") return "Generated by Orchestra at %s" % time def execute(self, server, async=False): from .models import BackendLog scripts = self.scripts state = BackendLog.STARTED if not scripts: state = BackendLog.SUCCESS log = BackendLog.objects.create(backend=self.get_name(), state=state, server=server) for method, commands in scripts: method(log, server, commands, async) if log.state != BackendLog.SUCCESS: break return log def append(self, *cmd): # aggregate commands acording to its execution method if isinstance(cmd[0], basestring): method = self.script_method cmd = cmd[0] else: method = self.function_method cmd = partial(*cmd) if not self.cmd_section or self.cmd_section[-1][0] != method: self.cmd_section.append((method, [cmd])) else: self.cmd_section[-1][1].append(cmd) def prepare(self): """ hook for executing something at the beging define functions or initialize state """ self.append( 'set -e\n' 'set -o pipefail' ) def commit(self): """ hook for executing something at the end apply the configuration, usually reloading a service reloading a service is done in a separated method in order to reload the service once in bulk operations """ self.append('exit 0') class ServiceController(ServiceBackend): actions = ('save', 'delete') abstract = True @classmethod def get_verbose_name(cls): return _("[S] %s") % super(ServiceController, cls).get_verbose_name() @classmethod def get_backends(cls): """ filter controller classes """ backends = super(ServiceController, cls).get_backends() return [ backend for backend in backends if ServiceController in backend.__mro__ ]