Add support for changing address and port of a server

Author: Pavlos Parissis

haproxyadmin/command_status.py

@@ -101,3 +101,8 @@
     "Can't find resolvers section.",
     "Can't find backend.",
 ]
+
+SUCCESS_STRING_ADDRESS = "IP changed from|no need to change the addr"
+SUCCESS_STRING_PORT = ("no need to change the addr, port changed from|no need "
+                       "to change the addr, no need to change the port"
+                      )

haproxyadmin/internal.py

@@ -513,18 +513,6 @@ def metric(self, name):
 
         return getattr(data, name)
 
-    @property
-    def address(self):
-        """
-        Return server address
-        """
-        data = self.stats_data()
-        return data.addr
-
-    def setaddress(self, new_address):
-        return self.command("set server {be}/{srv} addr {new_address}".format(
-            be=self.backend.name, srv=self._name, new_address=new_address))
-
     def stats(self):
         """Build dictionary for all statistics reported by HAProxy.
 

haproxyadmin/server.py

@@ -11,7 +11,9 @@
 
 """
 from haproxyadmin.utils import (calculate, cmd_across_all_procs, compare_values,
-                                should_die, check_command, converter)
+                                should_die, check_command, converter,
+                                check_command_addr_port, elements_of_list_same)
+from haproxyadmin.exceptions import IncosistentData
 
 
 STATE_ENABLE = 'enable'
@@ -130,21 +132,72 @@ def check_status(self):
         return compare_values(values)
 
     @property
-    def address(self):
-        return self._server_per_proc[0].address
+    def port(self):
+        """Return port of server.
 
-    def setaddress(self, new_address):
-        """
-        Set this server's address.
         :rtype: ``string``
         """
+        values = cmd_across_all_procs(
+            self._server_per_proc, 'metric', 'addr'
+        )
+
+        try:
+            value = compare_values(values)
+        except IncosistentData as exc:
+            ports_across_proc = [value[1].split(':')[1] for value in values]
+            if elements_of_list_same(ports_across_proc):
+                return ports_across_proc[0]
+            else:
+                raise exc
+        else:
+            return value.split(':')[1]
+
+    @port.setter
+    def port(self, port):
+        """Set server's port.
+
+        :param port: port to set.
+        :type port: ``string``
+        :rtype: ``bool``
+        """
+        cmd = "set server {}/{} addr {} port {}".format(
+            self.backendname, self.name, self.address, port
+        )
+        results = cmd_across_all_procs(self._server_per_proc, 'command', cmd)
+
+        return check_command_addr_port('port', results)
 
+    @property
+    def address(self):
+        """Return address of server.
+
+        :rtype: ``string``
+        """
         values = cmd_across_all_procs(
-            self._server_per_proc, 'setaddress', new_address=str(new_address)
+            self._server_per_proc, 'metric', 'addr'
         )
 
-        return compare_values(values)
+        try:
+            value = compare_values(values)
+        except IncosistentData as exc:
+            raise exc
+        else:
+            return value.split(':')[0]
+
+    @address.setter
+    def address(self, address):
+        """Set server's address.
+
+        :param address: address to set.
+        :type address: ``string``
+        :rtype: ``bool``
+        """
+        cmd = "set server {}/{} addr {}".format(
+            self.backendname, self.name, address
+        )
+        results = cmd_across_all_procs(self._server_per_proc, 'command', cmd)
 
+        return check_command_addr_port('addr', results)
 
     @property
     def last_status(self):

haproxyadmin/utils.py

@@ -14,11 +14,12 @@
 import stat
 from functools import wraps
 import six
+import re
 
 from haproxyadmin.exceptions import (CommandFailed, MultipleCommandResults,
                                      IncosistentData)
 from haproxyadmin.command_status import (ERROR_OUTPUT_STRINGS,
-                                         SUCCESS_OUTPUT_STRINGS)
+        SUCCESS_OUTPUT_STRINGS, SUCCESS_STRING_PORT, SUCCESS_STRING_ADDRESS)
 
 METRICS_SUM = [
     'CompressBpsIn',
@@ -321,6 +322,46 @@ def check_command(results):
     else:
         raise MultipleCommandResults(results)
 
+def check_command_addr_port(change_type, results):
+    """Check if command to set port or address was successfully executed.
+
+    Unfortunately, haproxy returns many different combinations of output when
+    we change the address or the port of the server and trying to determine
+    if address or port was successfully changed isn't that trivial.
+
+    So, after we change address or port, we check if the same output is
+    returned by all processes and we also check if a collection of specific
+    strings are part of the output. This is a suboptimal solution, but I
+    couldn't come up with something more elegant.
+
+    :param change_type: either ``addr`` or ``port``
+    :type change_type: ``string``
+    :param results: a list of tuples with 2 elements.
+
+          #. process number of HAProxy
+          #. message returned by HAProxy
+    :type results: ``list``
+    :return: ``True`` if command was successfully executed otherwise ``False``.
+    :rtype: ``bool``
+    :raise: :class:`.MultipleCommandResults`, :class:`.CommandFailed` and
+      :class:`ValueError`.
+    """
+    if change_type == 'addr':
+        _match = SUCCESS_STRING_ADDRESS
+    elif change_type == 'port':
+        _match = SUCCESS_STRING_PORT
+    else:
+        raise ValueError('invalid value for change_type')
+
+    if elements_of_list_same([msg[1] for msg in results]):
+        msg = results[0][1]
+        if re.match(_match, msg):
+            return True
+        else:
+            raise CommandFailed(msg)
+    else:
+        raise MultipleCommandResults(results)
+
 
 def calculate(name, metrics):
     """Perform the appropriate calculation across a list of metrics.