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'''Cobalt proxy provides client access to cobalt components'''
__revision__ = '$Revision:$'
import logging, socket, time, xmlrpclib, ConfigParser
class CobaltComponentError(Exception):
'''This error signals component connection errors'''
pass
class SafeProxy:
'''Wrapper for proxy'''
_cfile = ConfigParser.ConfigParser()
_cfile.read(['/etc/bcfg2.conf'])
_components = _cfile._sections['components']
_authinfo = ('root', _cfile.get('communication', 'password'))
_retries = 4
def __init__(self, component, url=None):
self.component = component
self.log = logging.getLogger(component)
if url != None:
address = url
else:
address = self.__get_location(component)
try:
self.proxy = xmlrpclib.ServerProxy(address)
except IOError, io_error:
self.log.error("Invalid server URL %s: %s" % (address, io_error))
raise CobaltComponentError
except:
self.log.error("Failed to initialize xml-rpc", exc_info=1)
def run_method(self, method_name, method_args):
''' Perform an XMLRPC invocation against the server'''
method = getattr(self.proxy, method_name)
for irs in range(self._retries):
try:
ret = apply(method, self._authinfo + method_args)
if irs > 0:
self.log.warning("Required %d attempts to contact %s for operation %s" %
(irs, self.component, method_name))
self.log.debug("%s completed successfully" % (method_name))
return ret
except xmlrpclib.ProtocolError:
self.log.error("Server failure: Protocol Error")
raise xmlrpclib.Fault(20, "Server Failure")
except xmlrpclib.Fault:
self.log.debug("Operation %s completed with fault" % (method_name))
raise
except socket.error, serr:
self.log.debug("Attempting %s (%d of %d) failed because %s" % (method_name, (irs+1),
self._retries, serr))
time.sleep(0.5)
except:
self.log.error("Unknown failure", exc_info=1)
break
raise xmlrpclib.Fault(20, 'Server Failure')
def __get_location(self, name):
'''Perform component location lookups if needed'''
if self._components.has_key(name):
return self._components[name]
slp = SafeProxy('service-location', url=self._cfile.get('components', 'service-location'))
try:
sdata = slp.run_method('LookupService',
([{'tag':'location', 'name':name, 'url':'*'}],))
except xmlrpclib.Fault:
raise CobaltComponentError, "No Such Component"
if sdata:
curl = sdata[0]['url']
self._components[name] = curl
return curl
class ComponentProxy(SafeProxy):
'''Component Proxy instantiates a SafeProxy to a component and registers local functions
based on its definition'''
name = 'dummy'
methods = []
def __init__(self, url=None):
SafeProxy.__init__(self, self.name, url)
for method in self.methods:
setattr(self, method, eval('lambda *x:self.run_method(method, x)',
{'self':self, 'method':method}))
class service_location(ComponentProxy):
'''service-location component-specific proxy'''
name = 'service-location'
methods = ['AssertService', 'LookupService', 'DeassertService']
class process_manager(ComponentProxy):
'''process manager specific component proxy'''
name = 'process-manager'
methods = ['CreateProcessGroup', 'GetProcessGroup']
class bcfg2(ComponentProxy):
'''bcfg2 client code'''
name = 'bcfg2'
methods = ['AssertProfile', 'GetConfig', 'GetProbes', 'RecvProbeData', 'RecvStats']
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