Handle bad membership members (#343)

Before this patch getting control instance failed on checking membership members
if some member payload is empty. It caused because an empty Lua table is serialized
as an empty array, but the Python module expects a dict. Since this patch, all empty
table cases are handled for membership.

Author: dokshina

CHANGELOG.md

@@ -15,6 +15,7 @@ README.md to use the newest tag with new release
 - Fail on getting control instance when all unjoined instances haven't
   `replicaset_alias` set
 - Support of Ansible 4.0
+- Handling of bad membership members - empty or with empty payload
 
 ### Added
 

library/cartridge_get_control_instance.py

@@ -93,6 +93,9 @@ def candidate_is_ok(uri, names_by_uris, module_hostvars):
 def get_control_instance_name(module_hostvars, play_hosts, control_console):
     members = get_membership_members(control_console)
 
+    if not members:
+        return None, "Membership is empty"
+
     # try to find joined alive instance that isn't set to be expelled
     alive_instances_uris = set()
     joined_instances_uris = set()
@@ -102,10 +105,16 @@ def get_control_instance_name(module_hostvars, play_hosts, control_console):
     names_by_uris = {}
 
     for uri, member in sorted(members.items()):
+        if not member:
+            return None, "Membership contains empty member with URI %s" % uri
+
         member_payload = member.get('payload')
         if member_payload is None:
             return None, "Instance with URI %s doesn't contain payload" % uri
 
+        if not member_payload:
+            return None, "Instance with URI %s has empty payload" % uri
+
         instance_name = member_payload.get('alias')
         if instance_name is None:
             return None, "Instance with URI %s payload doesn't contain alias" % uri

unit/instance.py

@@ -278,6 +278,11 @@ def set_membership_members(self, specified_members, with_payload=True):
 
         for m in specified_members:
             uri = m['uri']
+
+            if m.get('empty'):
+                members[uri] = {}
+                continue
+
             member = {
                 'uri': uri,
                 'status': m.get('status', 'alive'),
@@ -293,6 +298,9 @@ def set_membership_members(self, specified_members, with_payload=True):
                     }
                 })
 
+            if m.get('empty_payload'):
+                member.update({"payload": {}})
+
             members[uri] = member
 
         self.set_variable('membership_members', members)

unit/test_get_control_instance.py

@@ -59,12 +59,38 @@ def setUp(self):
 
         self.instance.start()
 
-    def test_instance_without_alias(self):
+    def test_bad_members(self):
         hostvars = get_instance_hostvars('instance-1')
+        hostvars.update(get_instance_hostvars('empty-member'))
+        hostvars.update(get_instance_hostvars('empty-payload'))
 
-        # with UUID (already bootstrapped) and without alias
+        # empty membership
+        self.instance.set_membership_members([])
+        res = call_get_control_instance('myapp', self.console_sock, hostvars)
+        self.assertTrue(res.failed)
+        self.assertIn("Membership is empty", res.msg)
+
+        # empty member
+        self.instance.set_membership_members([
+            utils.get_member('empty-member', empty=True),
+            utils.get_member('instance-1'),
+        ])
+        res = call_get_control_instance('myapp', self.console_sock, hostvars)
+        self.assertTrue(res.failed)
+        self.assertIn("Membership contains empty member with URI empty-member-uri", res.msg)
+
+        # with empty payload
+        self.instance.set_membership_members([
+            utils.get_member('empty-payload', empty_payload=True),
+            utils.get_member('instance-1'),
+        ])
+        res = call_get_control_instance('myapp', self.console_sock, hostvars)
+        self.assertTrue(res.failed)
+        self.assertIn("Instance with URI empty-payload-uri has empty payload", res.msg)
+
+        # without alias
         self.instance.set_membership_members([
-            utils.get_member('instance-1', with_uuid=True, with_alias=False),
+            utils.get_member('instance-1', with_alias=False),
         ])
         res = call_get_control_instance('myapp', self.console_sock, hostvars)
         self.assertTrue(res.failed)

unit/utils.py

@@ -1,6 +1,15 @@
-def get_member(alias, with_alias=True, uuid=None, with_uuid=False, status=None, state=None):
+def get_member(alias, with_alias=True, empty=False, empty_payload=False,
+               uuid=None, with_uuid=False, status=None, state=None):
     member = {'uri': '%s-uri' % alias}
 
+    if empty:
+        member.update({'empty': True})
+        return member
+
+    if empty_payload:
+        member.update({'empty_payload': True})
+        return member
+
     if with_alias:
         member.update({'alias': alias})