from functools import partial from django.db.models.loading import get_model from django.utils import timezone 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.BashSSH function_method = methods.Python type = 'task' # 'sync' ignore_fields = [] actions = [] # TODO type: 'script', execution:'task' __metaclass__ = plugins.PluginMount def __unicode__(self): return type(self).__name__ def __str__(self): return unicode(self) def __init__(self): self.cmds = [] @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) 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 state = BackendLog.STARTED if self.cmds else BackendLog.SUCCESS log = BackendLog.objects.create(backend=self.get_name(), state=state, server=server) for method, cmds in self.cmds: method(log, server, cmds, 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.cmds or self.cmds[-1][0] != method: self.cmds.append((method, [cmd])) else: self.cmds[-1][1].append(cmd) def prepare(self): """ hook for executing something at the beging """ pass def commit(self): """ 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 """ pass 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__ ]