From 79829d237326e31c9b768c558acd6443c74ae318 Mon Sep 17 00:00:00 2001
From: Guido Trotter <ultrotter@google.com>
Date: Sat, 16 Jun 2012 09:07:00 +0100
Subject: [PATCH] Allow single-homed <-> multi-homed transitions
To change the cluster from single homed to multi homed or vice versa one
must target the master node first, and pass the --force option. All
other nodes then will work as long as they are reachable by the master.
Note that this will also prevent a node to be set to single-homed if the
master is multi-homed, which wasn't disallowed before, and warn if a
single-homed <-> multi-homed transition happens.
Also note that it's still theoretically possible to flip a cluster
inadvertently by changing the master node this way, and then doing a
master failover before fixing the other nodes.
Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>
---
doc/admin.rst | 31 +++++++++++++++++++++++++++++++
lib/cmdlib.py | 26 +++++++++++++++++++++++---
man/gnt-node.rst | 7 ++++++-
3 files changed, 60 insertions(+), 4 deletions(-)
diff --git a/doc/admin.rst b/doc/admin.rst
index 8850187e0..80028e6ec 100644
--- a/doc/admin.rst
+++ b/doc/admin.rst
@@ -912,6 +912,37 @@ it's easy to remove it from the cluster::
This will deconfigure the node, stop the ganeti daemons on it and leave
it hopefully like before it joined to the cluster.
+Replication network changes
++++++++++++++++++++++++++++
+
+The :command:`gnt-node modify -s` command can be used to change the
+secondary IP of a node. This operation can only be performed if:
+
+- No instance is active on the target node
+- The new target IP is reachable from the master's secondary IP
+
+Also this operation will not allow to change a node from single-homed
+(same primary and secondary ip) to multi-homed (separate replication
+network) or vice versa, unless:
+
+- The target node is the master node and `--force` is passed.
+- The target cluster is single-homed and the new primary ip is a change
+ to single homed for a particular node.
+- The target cluster is multi-homed and the new primary ip is a change
+ to multi homed for a particular node.
+
+For example to do a single-homed to multi-homed conversion::
+
+ $ gnt-node modify --force -s %SECONDARY_IP% %MASTER_NAME%
+ $ gnt-node modify -s %SECONDARY_IP% %NODE1_NAME%
+ $ gnt-node modify -s %SECONDARY_IP% %NODE2_NAME%
+ $ gnt-node modify -s %SECONDARY_IP% %NODE3_NAME%
+ ...
+
+The same commands can be used for multi-homed to single-homed except the
+secondary IPs should be the same as the primaries for each node, for
+that case.
+
Storage handling
++++++++++++++++
diff --git a/lib/cmdlib.py b/lib/cmdlib.py
index ba6661c38..3a22ef53a 100644
--- a/lib/cmdlib.py
+++ b/lib/cmdlib.py
@@ -5996,13 +5996,33 @@ class LUNodeSetParams(LogicalUnit):
" without using re-add. Please make sure the node"
" is healthy!")
+ # When changing the secondary ip, verify if this is a single-homed to
+ # multi-homed transition or vice versa, and apply the relevant
+ # restrictions.
if self.op.secondary_ip:
# Ok even without locking, because this can't be changed by any LU
master = self.cfg.GetNodeInfo(self.cfg.GetMasterNode())
master_singlehomed = master.secondary_ip == master.primary_ip
- if master_singlehomed and self.op.secondary_ip:
- raise errors.OpPrereqError("Cannot change the secondary ip on a single"
- " homed cluster", errors.ECODE_INVAL)
+ if master_singlehomed and self.op.secondary_ip != node.primary_ip:
+ if self.op.force and node.name == master.name:
+ self.LogWarning("Transitioning from single-homed to multi-homed"
+ " cluster. All nodes will require a secondary ip.")
+ else:
+ raise errors.OpPrereqError("Changing the secondary ip on a"
+ " single-homed cluster requires the"
+ " --force option to be passed, and the"
+ " target node to be the master",
+ errors.ECODE_INVAL)
+ elif not master_singlehomed and self.op.secondary_ip == node.primary_ip:
+ if self.op.force and node.name == master.name:
+ self.LogWarning("Transitioning from multi-homed to single-homed"
+ " cluster. Secondary IPs will have to be removed.")
+ else:
+ raise errors.OpPrereqError("Cannot set the secondary IP to be the"
+ " same as the primary IP on a multi-homed"
+ " cluster, unless the --force option is"
+ " passed, and the target node is the"
+ " master", errors.ECODE_INVAL)
assert not (frozenset(affected_instances) -
self.owned_locks(locking.LEVEL_INSTANCE))
diff --git a/man/gnt-node.rst b/man/gnt-node.rst
index 35683c8cd..5dabe5c69 100644
--- a/man/gnt-node.rst
+++ b/man/gnt-node.rst
@@ -313,7 +313,12 @@ candidate role if is in that role)::
The ``-s (--secondary-ip)`` option can be used to change the node's
secondary ip. No drbd instances can be running on the node, while this
-operation is taking place.
+operation is taking place. Remember that the secondary ip must be
+reachable from the master secondary ip, when being changed, so be sure
+that the node has the new IP already configured and active. In order to
+convert a cluster from single homed to multi-homed or vice versa
+``--force`` is needed as well, and the target node for the first change
+must be the master.
See **ganeti(7)** for a description of ``--submit`` and other common
options.
--
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