Scale-in and Scale-out of mysql-innodb-cluster

Handle adding and removing units to the mysql-innodb-cluster.

Change-Id: Ie658c42b095bcff822cdfb0b771d41704ddc85ea
Closes-Bug: #1877546
Closes-Bug: #1874479

.gitreview

@@ -0,0 +1,4 @@
+[gerrit]
+host=review.opendev.org
+port=29418
+project=openstack/charm-interface-mysql-innodb-cluster.git

.zuul.yaml

@@ -0,0 +1,4 @@
+- project:
+    templates:
+      - python35-charm-jobs
+      - openstack-python3-ussuri-jobs

peers.py

@@ -14,6 +14,7 @@
 
 from charms import reactive
 import charmhelpers.contrib.network.ip as ch_net_ip
+import charmhelpers.core as ch_core
 
 
 class MySQLInnoDBClusterPeer(reactive.Endpoint):
@@ -36,7 +37,8 @@ class MySQLInnoDBClusterPeer(reactive.Endpoint):
     @property
     def peer_relation(self):
         # Get the first relation object as we only have one relation to peers
-        return self.relations[0]
+        for relation in self.relations:
+            return relation
 
     def available(self):
         if len(self.all_joined_units) < (self.minimum_cluster_size - 1):
@@ -50,6 +52,12 @@ class MySQLInnoDBClusterPeer(reactive.Endpoint):
                 return False
         return True
 
+    def set_or_clear_available(self):
+        if self.available():
+            reactive.set_flag(self.expand_name('{endpoint_name}.available'))
+        else:
+            reactive.clear_flag(self.expand_name('{endpoint_name}.available'))
+
     def clustered(self):
         if len(self.all_joined_units) < (self.minimum_cluster_size - 1):
             return False
@@ -60,8 +68,9 @@ class MySQLInnoDBClusterPeer(reactive.Endpoint):
 
     @reactive.when('endpoint.{endpoint_name}.joined')
     def joined(self):
-        reactive.set_flag(self.expand_name('{endpoint_name}.connected'))
         self.set_ingress_address()
+        reactive.set_flag(self.expand_name('{endpoint_name}.connected'))
+        self.set_or_clear_available()
 
     @reactive.when('endpoint.{endpoint_name}.changed')
     def changed(self):
@@ -82,19 +91,14 @@ class MySQLInnoDBClusterPeer(reactive.Endpoint):
             for flag in flags:
                 reactive.clear_flag(flag)
 
-        if self.available():
-            reactive.set_flag(self.expand_name('{endpoint_name}.available'))
-        else:
-            reactive.clear_flag(self.expand_name('{endpoint_name}.available'))
+        self.set_or_clear_available()
 
         if self.clustered():
             reactive.set_flag(self.expand_name('{endpoint_name}.clustered'))
         else:
             reactive.clear_flag(self.expand_name('{endpoint_name}.clustered'))
 
-    @reactive.when_any('endpoint.{endpoint_name}.broken',
-                       'endpoint.{endpoint_name}.departed')
-    def departed(self):
+    def remove(self):
         flags = (
             self.expand_name('{endpoint_name}.connected'),
             self.expand_name('{endpoint_name}.available'),
@@ -102,6 +106,14 @@ class MySQLInnoDBClusterPeer(reactive.Endpoint):
         for flag in flags:
             reactive.clear_flag(flag)
 
+    @reactive.when('endpoint.{endpoint_name}.departed')
+    def departed(self):
+        self.remove()
+
+    @reactive.when('endpoint.{endpoint_name}.broken')
+    def broken(self):
+        self.remove()
+
     def set_cluster_connection_info(
             self, cluster_address, cluster_user, cluster_password):
         """Send cluster connection information to peers.
@@ -116,6 +128,11 @@ class MySQLInnoDBClusterPeer(reactive.Endpoint):
         :returns: None, this function is called for its side effect
         :rtype: None
         """
+        if not self.peer_relation:
+            ch_core.hookenv.log(
+                "No mysql-inndb-cluster peer relation: possibly departing.",
+                "WARNING")
+            return
         self.peer_relation.to_publish['cluster-address'] = cluster_address
         self.peer_relation.to_publish['cluster-user'] = cluster_user
         self.peer_relation.to_publish['cluster-password'] = cluster_password
@@ -127,6 +144,11 @@ class MySQLInnoDBClusterPeer(reactive.Endpoint):
         :returns: None, this function is called for its side effect
         :rtype: None
         """
+        if not self.peer_relation:
+            ch_core.hookenv.log(
+                "No mysql-inndb-cluster peer relation: possibly departing.",
+                "WARNING")
+            return
         self.peer_relation.to_publish['unit-configure-ready'] = True
 
     def set_unit_clustered(self):
@@ -136,4 +158,9 @@ class MySQLInnoDBClusterPeer(reactive.Endpoint):
         :returns: None, this function is called for its side effect
         :rtype: None
         """
+        if not self.peer_relation:
+            ch_core.hookenv.log(
+                "No mysql-inndb-cluster peer relation: possibly departing.",
+                "WARNING")
+            return
         self.peer_relation.to_publish['unit-clustered'] = True

test-requirements.txt

@@ -1,5 +1,5 @@
 charms.reactive
-flake8>=2.2.4,<=2.4.1
+flake8>=2.2.4
 mock>=1.2
 stestr>=2.2.0
 git+https://github.com/openstack/charms.openstack.git#egg=charms.openstack

unit_tests/test_peers.py

@@ -28,8 +28,9 @@ class TestRegisteredHooks(test_utils.TestRegisteredHooks):
 
                 "changed": (
                     "endpoint.{endpoint_name}.changed",),
-                "departed": ("endpoint.{endpoint_name}.broken",
-                             "endpoint.{endpoint_name}.departed",),
+                "departed": ("endpoint.{endpoint_name}.departed",),
+
+                "broken": ("endpoint.{endpoint_name}.broken",),
             },
         }
         # test that the hooks were registered