Add failover to the XML-RPC client

433506

ipa-python/config.py

@@ -23,6 +23,7 @@ from optparse import OptionParser
 import krbV
 import socket
 import ipa.dnsclient
+import re
 
 class IPAConfigError(Exception):
     def __init__(self, msg=''):
@@ -37,7 +38,7 @@ class IPAConfigError(Exception):
 class IPAConfig:
     def __init__(self):
         self.default_realm = None
-        self.default_server = None
+        self.default_server = []
 
     def get_realm(self):
         if self.default_realm:
@@ -62,7 +63,8 @@ def __parse_config():
         if not config.default_realm:
             config.default_realm = p.get("defaults", "realm")
         if not config.default_server:
-            config.default_server = p.get("defaults", "server")
+            s = p.get("defaults", "server")
+            config.default_server = re.sub("\s+", "", s).split(',')
     except:
         pass
 
@@ -95,12 +97,12 @@ def __discover_config():
             for r in rs:
                 if r.dns_type == ipa.dnsclient.DNS_T_SRV:
                     rsrv = r.rdata.server.rstrip(".")
-                    # we take only the first one returned for now
-                    config.default_server = rsrv
-                    return True
+                    config.default_server.append(rsrv)
 
-        #if none found
-        return False
+        if config.default_server:
+            return True
+        else:
+            return False
     except:
         return False
 

ipa-python/rpcclient.py

@@ -20,6 +20,7 @@
 import xmlrpclib
 import socket
 import config
+import errno
 from krbtransport import KerbTransport
 from kerberos import GSSError
 from ipa import ipaerror, ipautil
@@ -31,16 +32,34 @@ from ipa import config
 class RPCClient:
 
     def __init__(self):
+        self.server = None
         config.init_config()
     
-    def server_url(self):
+    def server_url(self, server):
         """Build the XML-RPC server URL from our configuration"""
-        return "https://" + config.config.get_server() + "/ipa"
+        return "https://" + server + "/ipa"
     
     def setup_server(self):
         """Create our XML-RPC server connection using kerberos
            authentication"""
-        return xmlrpclib.ServerProxy(self.server_url(), KerbTransport())
+        if not self.server:
+            serverlist = config.config.get_server()
+
+            # Try each server until we succeed or run out of servers to try
+            # Guaranteed by ipa.config to have at least 1 in the list
+            for s in serverlist:
+                try:
+                    self.server = s
+                    remote = xmlrpclib.ServerProxy(self.server_url(s), KerbTransport())
+                    result = remote.ping()
+                    break
+                except socket.error, e:
+                    if (e[0] == errno.ECONNREFUSED) or (e[0] == errno.ECONNREFUSED) or (e[0] == errno.EHOSTDOWN) or (e[0] == errno.EHOSTUNREACH):
+                        continue
+                    else:
+                        raise e
+
+        return xmlrpclib.ServerProxy(self.server_url(self.server), KerbTransport())
     
 # Higher-level API
 

ipa-server/xmlrpc-server/ipaxmlrpc.py

@@ -91,6 +91,7 @@ class ModXMLRPCRequestHandler(object):
         self.funcs = {}
         self.traceback = False
         #introspection functions
+        self.register_function(self.ping, name="ping")
         self.register_function(self.list_api, name="_listapi")
         self.register_function(self.system_listMethods, name="system.listMethods")
         self.register_function(self.system_methodSignature, name="system.methodSignature")
@@ -240,6 +241,10 @@ class ModXMLRPCRequestHandler(object):
                           'args': args})
         return funcs
 
+    def ping(self,opts):
+        """Simple test to see if the XML-RPC is up and active."""
+        return "pong"
+
     def _getFuncArgs(self, func):
         args = []
         for x in range(0, func.func_code.co_argcount):

ipa-server/xmlrpc-server/test/test_methods.py

@@ -24,7 +24,8 @@ from ipa import config
 
 ipa.config.init_config()
 
-url = "http://" + config.config.get_server() + "/ipa"
+serverlist = config.config.get_server()
+url = "http://" + serverlist[0] + "/ipa"
 s = xmlrpclib.Server(url, KerbTransport())
 
 print "A list of all methods available on the server."