[PATCH stable-2.15 1/2] Allow the Transport class to be used for non-master nodes

['Petr Pudlak' via ganeti-devel]

If a communication failure occurred and the caller was not running on
the master node, Transport assumed that this itself was the cause of
the error condition.

However, for communication with the metadata daemon we need to support
non-master nodes as well.

Add a parameter that allows to use the class on non-master nodes.

Signed-off-by: Petr Pudlak <pud...@google.com>
---
 lib/rpc/transport.py | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/lib/rpc/transport.py b/lib/rpc/transport.py
index 88f30a9..3729c06 100644
--- a/lib/rpc/transport.py
+++ b/lib/rpc/transport.py
@@ -64,7 +64,7 @@ class Transport:
 
   """
 
-  def __init__(self, address, timeouts=None):
+  def __init__(self, address, timeouts=None, allow_non_master=None):
     """Constructor for the Client class.
 
     Arguments:
@@ -98,7 +98,8 @@ class Transport:
       # Try to connect
       try:
         utils.Retry(self._Connect, 1.0, self._ctimeout,
-                    args=(self.socket, address, self._ctimeout))
+                    args=(self.socket, address, self._ctimeout,
+                          allow_non_master))
       except utils.RetryTimeout:
         raise errors.TimeoutError("Connect timed out")
 
@@ -110,7 +111,7 @@ class Transport:
       raise
 
   @staticmethod
-  def _Connect(sock, address, timeout):
+  def _Connect(sock, address, timeout, allow_non_master):
     sock.settimeout(timeout)
     try:
       sock.connect(address)
@@ -119,15 +120,16 @@ class Transport:
     except socket.error, err:
       error_code = err.args[0]
       if error_code in (errno.ENOENT, errno.ECONNREFUSED):
-        # Verify if we're acutally on the master node before trying
-        # again.
-        ss = ssconf.SimpleStore()
-        try:
-          master, myself = ssconf.GetMasterAndMyself(ss=ss)
-        except ganeti.errors.ConfigurationError:
-          raise errors.NoMasterError(address)
-        if master != myself:
-          raise errors.NoMasterError(address)
+        if not allow_non_master:
+          # Verify if we're acutally on the master node before trying
+          # again.
+          ss = ssconf.SimpleStore()
+          try:
+            master, myself = ssconf.GetMasterAndMyself(ss=ss)
+          except ganeti.errors.ConfigurationError:
+            raise errors.NoMasterError(address)
+          if master != myself:
+            raise errors.NoMasterError(address)
         raise utils.RetryAgain()
       elif error_code in (errno.EPERM, errno.EACCES):
         raise errors.PermissionError(address)
-- 
2.2.0.rc0.207.ga3a616c