glusterd/geo-rep: slave volume uuid to identify a geo-rep session

Problem:
Currently, it is possible to create multiple geo-rep session from
the Master host to Slave host(s), where Slave host(s) belonging
to the same volume.

For example:
Consider Master Host M1 having volume tv1 and Slave volume tv2,
which spans across two Slave hosts S1 and S2.
Currently, it is possible to create geo-rep session from
M1(tv1) to S1(tv2) as well as from M1(tv1) to S2(tv2).

When the Slave Host is alone modified, it is identified as a new geo-rep
session (as slave host and slave volume together are identifying
Slave side).

Also, it is possible to create both root and non-root geo-rep session between
same Master volume and Slave volume. This should also be avoided.

Solution:
This multiple geo-rep session creation must be avoided and
in order to avoid, use Slave volume uuid to identify a Slave.
This way, we can identify whether a session is already created for
the same Slave volume and avoid creating again (using different host).

When the session creation is forced in the above scenario, rename
the existing geo-rep session directory with new Slave Host mentioned.

Change-Id: I9239759cbc0d15dad63c48b8cf62950bb687c7c8
BUG: 1336704
Signed-off-by: Saravanakumar Arumugam <sarumuga@redhat.com>
Signed-off-by: Aravinda VK <avishwan@redhat.com>
Reviewed-on: http://review.gluster.org/13111
Reviewed-by: Kotresh HR <khiremat@redhat.com>
Tested-by: Kotresh HR <khiremat@redhat.com>
Smoke: Gluster Build System <jenkins@build.gluster.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Atin Mukherjee <amukherj@redhat.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.com>
(cherry picked from commit a9128cda34b1f696b717ba09fa0ac5a929be8969)
Reviewed-on: http://review.gluster.org/14372

2 files changed, 57 insertions, 0 deletions

diff --git a/geo-replication/syncdaemon/configinterface.py.in b/geo-replication/syncdaemon/configinterface.py.in
index f8df49935f1..0570061955f 100644
--- a/geo-replication/syncdaemon/configinterface.py.in
+++ b/geo-replication/syncdaemon/configinterface.py.in
@@ -64,6 +64,18 @@ CONFIGS = (
      "ignore_deletes",
      "true",
      "false"),
+    ("peersrx . .",
+     "pid-file",
+     "@GLUSTERD_WORKDIR@/geo-replication/${mastervol}_${remotehost}_"
+     "${slavevol}/${eSlave}.pid",
+     "@GLUSTERD_WORKDIR@/geo-replication/${mastervol}_${remotehost}_"
+     "${slavevol}/monitor.pid"),
+    ("peersrx . .",
+     "state-file",
+     "@GLUSTERD_WORKDIR@/geo-replication/${mastervol}_${remotehost}_"
+     "${slavevol}/${eSlave}.status",
+     "@GLUSTERD_WORKDIR@/geo-replication/${mastervol}_${remotehost}_"
+     "${slavevol}/monitor.status"),
 )
 
 
diff --git a/geo-replication/syncdaemon/gsyncd.py b/geo-replication/syncdaemon/gsyncd.py
index fdb5348d363..1667e97b245 100644
--- a/geo-replication/syncdaemon/gsyncd.py
+++ b/geo-replication/syncdaemon/gsyncd.py
@@ -32,9 +32,14 @@ from syncdutils import GsyncdError, select, set_term_handler
 from configinterface import GConffile, upgrade_config_file
 import resource
 from monitor import monitor
+import xml.etree.ElementTree as XET
+from subprocess import PIPE
+import subprocess
 from changelogagent import agent, Changelog
 from gsyncdstatus import set_monitor_status, GeorepStatus
 
+ParseError = XET.ParseError if hasattr(XET, 'ParseError') else SyntaxError
+
 
 class GLogger(Logger):
 
@@ -112,6 +117,36 @@ class GLogger(Logger):
         gconf.log_exit = True
 
 
+# Given slave host and its volume name, get corresponding volume uuid
+def slave_vol_uuid_get(host, vol):
+    po = subprocess.Popen(['gluster', '--xml', '--remote-host=' + host,
+                           'volume', 'info', vol], bufsize=0,
+                          stdin=None, stdout=PIPE, stderr=PIPE)
+    vix, err = po.communicate()
+    if po.returncode != 0:
+        logging.info("Volume info failed, unable to get "
+                     "volume uuid of %s present in %s,"
+                     "returning empty string: %s" %
+                     (vol, host, po.returncode))
+        return ""
+    vi = XET.fromstring(vix)
+    if vi.find('opRet').text != '0':
+        logging.info("Unable to get volume uuid of %s, "
+                     "present in %s returning empty string: %s" %
+                     (vol, host, vi.find('opErrstr').text))
+        return ""
+
+    try:
+        voluuid = vi.find("volInfo/volumes/volume/id").text
+    except (ParseError, AttributeError, ValueError) as e:
+        logging.info("Parsing failed to volume uuid of %s, "
+                     "present in %s returning empty string: %s" %
+                     (vol, host, e))
+        voluuid = ""
+
+    return voluuid
+
+
 def startup(**kw):
     """set up logging, pidfile grabbing, daemonization"""
     if getattr(gconf, 'pid_file', None) and kw.get('go_daemon') != 'postconn':
@@ -314,6 +349,8 @@ def main_i():
                   action='callback', callback=store_local_curry('dont'))
     op.add_option('--verify', type=str, dest="verify",
                   action='callback', callback=store_local)
+    op.add_option('--slavevoluuid-get', type=str, dest="slavevoluuid_get",
+                  action='callback', callback=store_local)
     op.add_option('--create', type=str, dest="create",
                   action='callback', callback=store_local)
     op.add_option('--delete', dest='delete', action='callback',
@@ -375,6 +412,14 @@ def main_i():
     defaults = op.get_default_values()
     opts, args = op.parse_args(values=optparse.Values())
     args_orig = args[:]
+
+    voluuid_get = rconf.get('slavevoluuid_get')
+    if voluuid_get:
+        slave_host, slave_vol = voluuid_get.split("::")
+        svol_uuid = slave_vol_uuid_get(slave_host, slave_vol)
+        print svol_uuid
+        return
+
     r = rconf.get('resource_local')
     if r:
         if len(args) == 0: