Better control of mariadb restarts in upgrades

This commit adds additional control around how the galera cluster
nodes are restarted during an upgrade (both the openstack upgrade
as well as mariadb upgrade). lxc config that gets added during the
lxc-container-create play would normally force a container restart.
This commit essentially does the following:

- run lxc-container-create on galera nodes but prevent container restarts
  from being triggered by the new lxc config that gets laid down
- run a mariadb upgrade
- run a controlled rolling restart of all mariadb cluster containers

Change-Id: I5d979eb15c471274cc14ce6f41c8ae479c5131d6

releasenotes/notes/mariadb-rolling-upgrades-323510425c3c7751.yaml

@@ -0,0 +1,8 @@
+---
+upgrade:
+  - During upgrades, container and service restarts for the mariadb/galera
+    cluster were being triggered multiple times and causing the cluster to
+    become unstable and often unrecoverable. This situation has been improved
+    immensely, and we now have tight control such that restarts of the galera
+    containers only need to happen once, and are done so in a controlled,
+    predictable and repeatable way.

scripts/run-upgrade.sh

@@ -145,11 +145,24 @@ function main {
         RUN_TASKS+=("${UPGRADE_PLAYBOOKS}/deploy-config-changes.yml")
         RUN_TASKS+=("${UPGRADE_PLAYBOOKS}/user-secrets-adjustment.yml")
         RUN_TASKS+=("${UPGRADE_PLAYBOOKS}/db-collation-alter.yml")
-        RUN_TASKS+=("setup-hosts.yml --limit '!galera_all[0]'")
+        # we don't want to trigger galera container restarts yet
-        RUN_TASKS+=("lxc-containers-create.yml --limit galera_all[0]")
+        RUN_TASKS+=("setup-hosts.yml --limit '!galera_all'")
+        # add new container config to galera containers but don't restart
+        RUN_TASKS+=("lxc-containers-create.yml -e 'lxc_container_allow_restarts=false' --limit galera_all")
+	# rebuild the repo servers
+        RUN_TASKS+=("repo-install.yml")
         RUN_TASKS+=("${UPGRADE_PLAYBOOKS}/repo-server-pip-conf-removal.yml")
         RUN_TASKS+=("${UPGRADE_PLAYBOOKS}/old-hostname-compatibility.yml")
-        RUN_TASKS+=("setup-infrastructure.yml -e 'galera_upgrade=true' -e 'rabbitmq_upgrade=true'")
+        # explicitly perform mariadb upgrade
+        RUN_TASKS+=("galera-install.yml -e 'galera_upgrade=true'")
+        # explicitly perform controlled galera cluster restart
+        RUN_TASKS+=("${UPGRADE_PLAYBOOKS}/galera-cluster-rolling-restart.yml")
+        # individually run each of the remaining plays from setup-infrastructure
+        RUN_TASKS+=("haproxy-install.yml")
+        RUN_TASKS+=("memcached-install.yml")
+        RUN_TASKS+=("rabbitmq-install.yml -e 'rabbitmq_upgrade=true'")
+        RUN_TASKS+=("utility-install.yml")
+        RUN_TASKS+=("rsyslog-install.yml")
         RUN_TASKS+=("${UPGRADE_PLAYBOOKS}/memcached-flush.yml")
         RUN_TASKS+=("setup-openstack.yml")
         # Run the tasks in order

scripts/upgrade-utilities/playbooks/galera-cluster-rolling-restart.yml

@@ -0,0 +1,59 @@
+---
+# Copyright 2016, Rackspace US, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+- name: Gracefully restart mariadb/galera cluster
+  hosts: galera_all
+  serial: 1
+  max_fail_percentage: 0
+  gather_facts: false
+  user: root
+  tasks:
+    - name: Stop mariadb
+      service:
+        name: mysql
+        state: stopped
+      retries: 5
+      delay: 10
+
+    - name: Stop container
+      lxc_container:
+        name: "{{ inventory_hostname }}"
+        state: "stopped"
+      delegate_to: "{{ physical_host }}"
+
+    - name: Start container
+      lxc_container:
+        name: "{{ inventory_hostname }}"
+        state: "started"
+      delegate_to: "{{ physical_host }}"
+
+  post_tasks:
+    - name: Wait for mariadb port 3306 to be available
+      local_action:
+        module: wait_for
+        port: "3306"
+        host: "{{ ansible_ssh_host | default(inventory_hostname) }}"
+        search_regex: MariaDB
+      retries: 10
+      delay: 10
+
+    - name: Check that WSREP is ready and Synced
+      shell: "/usr/bin/mysqladmin --defaults-file=/etc/mysql/debian.cnf extended-status | egrep '(wsrep_local_state_comment)'"
+      register: mysql_ready
+      until:
+        - mysql_ready.rc == 0
+        - (mysql_ready.stdout).find("Synced") != -1
+      retries: 60
+      delay: 1