cluster-merge: implement params delta mercifulness

Sometimes it's good to tell the user about parameter differences but
then proceed anyway. Strictness is still enforced for those parameters
that would break the cluster (volume group name, storage dir if file
storage is enabled).

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>

tools/cluster-merge

@@ -49,6 +49,9 @@ _RESTART_ALL = "all"
 _RESTART_UP = "up"
 _RESTART_NONE = "none"
 _RESTART_CHOICES = (_RESTART_ALL, _RESTART_UP, _RESTART_NONE)
+_PARAMS_STRICT = "strict"
+_PARAMS_WARN = "warn"
+_PARAMS_CHOICES = (_PARAMS_STRICT, _PARAMS_WARN)
 
 
 PAUSE_PERIOD_OPT = cli.cli_option("-p", "--watcher-pause-period", default=1800,
@@ -62,6 +65,14 @@ GROUPS_OPT = cli.cli_option("--groups", default=None, metavar="STRATEGY",
                             help=("How to handle groups that have the"
                                   " same name (One of: %s/%s)" %
                                   (_GROUPS_MERGE, _GROUPS_RENAME)))
+PARAMS_OPT = cli.cli_option("--parameter-conflicts", default=_PARAMS_STRICT,
+                            metavar="STRATEGY",
+                            choices=_PARAMS_CHOICES,
+                            dest="params",
+                            help=("How to handle params that have"
+                                  " different values (One of: %s/%s)" %
+                                  _PARAMS_CHOICES))
+
 RESTART_OPT = cli.cli_option("--restart", default=_RESTART_ALL,
                              metavar="STRATEGY",
                              choices=_RESTART_CHOICES,
@@ -113,7 +124,7 @@ class Merger(object):
   """Handling the merge.
 
   """
-  def __init__(self, clusters, pause_period, groups, restart):
+  def __init__(self, clusters, pause_period, groups, restart, params):
     """Initialize object with sane defaults and infos required.
 
     @param clusters: The list of clusters to merge in
@@ -130,6 +141,7 @@ class Merger(object):
     self.ssh_runner = ssh.SshRunner(self.cluster_name)
     self.groups = groups
     self.restart = restart
+    self.params = params
     if self.restart == _RESTART_UP:
       raise NotImplementedError
 
@@ -328,12 +340,10 @@ class Merger(object):
                               _CLUSTERMERGE_ECID + str(fake_ec_id))
         fake_ec_id += 1
 
-  # R0201: Method could be a function
   def _MergeClusterConfigs(self, my_config, other_config):
     """Checks that all relevant cluster parameters are compatible
 
     """
-    # pylint: disable-msg=R0201
     my_cluster = my_config.GetClusterInfo()
     other_cluster = other_config.GetClusterInfo()
     err_count = 0
@@ -353,10 +363,20 @@ class Merger(object):
       "primary_ip_family",
       "tags",
       "uid_pool",
-      "volume_group_name",
       ]
+    check_params_strict = [
+      "volume_group_name",
+    ]
     if constants.ENABLE_FILE_STORAGE:
-      check_params.append("file_storage_dir")
+      check_params_strict.append("file_storage_dir")
+    if constants.ENABLE_SHARED_FILE_STORAGE:
+      check_params_strict.append("shared_file_storage_dir")
+    check_params.extend(check_params_strict)
+
+    if self.params == _PARAMS_STRICT:
+      params_strict = True
+    else:
+      params_strict = False
 
     for param_name in check_params:
       my_param = getattr(my_cluster, param_name)
@@ -366,7 +386,8 @@ class Merger(object):
                       " differs to this cluster's value (%s)",
                       other_param, param_name, other_cluster.cluster_name,
                       my_param)
-        err_count += 1
+        if params_strict or param_name in check_params_strict:
+          err_count += 1
 
     #
     # Custom checks
@@ -390,7 +411,6 @@ class Merger(object):
       err_count += 1
 
     # Check hypervisor params for hypervisors we care about
-    # TODO: we probably don't care about all params for a given hypervisor
     for hyp in my_cluster.enabled_hypervisors:
       for param in my_cluster.hvparams[hyp]:
         my_value = my_cluster.hvparams[hyp][param]
@@ -401,7 +421,8 @@ class Merger(object):
                         " (%s)",
                         other_value, param, hyp, other_cluster.cluster_name,
                         my_value)
-          err_count += 1
+          if params_strict:
+            err_count += 1
 
     # Check os hypervisor params for hypervisors we care about
     for os_name in set(my_cluster.os_hvp.keys() + other_cluster.os_hvp.keys()):
@@ -414,7 +435,8 @@ class Merger(object):
                         " (%s)",
                         other_os_hvp, os_name, hyp, other_cluster.cluster_name,
                         my_os_hvp)
-          err_count += 1
+          if params_strict:
+            err_count += 1
 
     #
     # Warnings
@@ -455,7 +477,8 @@ class Merger(object):
                       " this cluster's parameters (%s)",
                       osparams, os_, other_cluster.cluster_name,
                       my_cluster.osparams[os_])
-        err_count += 1
+        if params_strict:
+          err_count += 1
 
     if err_count:
       raise errors.ConfigurationError("Cluster config for %s has incompatible"
@@ -718,6 +741,7 @@ def main():
   parser.add_option(PAUSE_PERIOD_OPT)
   parser.add_option(GROUPS_OPT)
   parser.add_option(RESTART_OPT)
+  parser.add_option(PARAMS_OPT)
 
   (options, args) = parser.parse_args()
 
@@ -727,7 +751,7 @@ def main():
     parser.error("No clusters specified")
 
   cluster_merger = Merger(utils.UniqueSequence(args), options.pause_period,
-                          options.groups, options.restart)
+                          options.groups, options.restart, options.params)
   try:
     try:
       cluster_merger.Setup()