Change mount states to ensure uptime

The mount role was using the systemd module to start / stop mounts
however if a mount was restarted when it could have been reloaded
the role could create a fair amount of chaos in a running environment.
This change maps the mount states appropriately to the systemctl command
options to ensure we're not needlessly restarting mounts should the unit
files change. The `systemd_mount_states` has been added which will map
the normal Ansible states to suitable systemd mount states and the mount
state is being managed using the `systemctl` command instead of the
ansible module.

Change-Id: I5c7e5105e54d3ff9ad040f2a1d003d3dd12e4efb
Signed-off-by: Kevin Carter <kevin.carter@rackspace.com>

tasks/systemd_mounts.yml

@@ -13,8 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+- name: Set mount facts
+  set_fact:
+    systemd_mount_suffix: "{{ (item.type == 'swap') | ternary('swap', 'mount') }}"
+    systemd_mount_item: "{{ item.where | default(item.what) }}"
+
 - name: Escape mount service file name
-  command: systemd-escape -p --suffix="{{ (item.type == 'swap') | ternary('swap', 'mount') }}" "{{ item.where | default(item.what) }}"
+  command: systemd-escape -p --suffix="{{ systemd_mount_suffix }}" "{{ systemd_mount_item }}"
   changed_when: false
   register: mount_service_name
 
@@ -46,20 +51,39 @@
   tags:
     - systemd-mount
 
-- name: Load mount(s)
+- name: Load or Unload mount(s)
   systemd:
     daemon_reload: yes
     name: "{{ mount_service_name.stdout }}"
     enabled: "{{ item.enabled | default(true) }}"
-    state: "{{ item.state | default(omit) }}"
   when:
     - item.state | default('unknown') != 'absent'
 
+# NOTE(cloudnull): The systemd module is not used to start the
+#                  mount because we don't want to inavertently
+#                  "restart" a mount unnecessarily. To ensure
+#                  we're able to load new options without
+#                  requiring a mount restart the systemctl
+#                  command is used with the "reload-or-restart"
+#                  argument. Additionally this command escapes
+#                  the name of the mount.
+- name: Set the state of the mount
+  shell: >-
+    systemctl
+    {{ systemd_mount_states[item.state] }}
+    $(systemd-escape -p --suffix="{{ systemd_mount_suffix }}" "{{ systemd_mount_item }}")
+  args:
+    warn: no
+  when:
+    - item.state is defined
+  tags:
+    - skip_ansible_lint
+
 - name: Unload mount(s)
   systemd:
     daemon_reload: yes
     name: "{{ mount_service_name.stdout }}"
-    enabled: "stopped"
+    enabled: false
     no_block: yes
   when:
     - item.state | default('unknown') == 'absent'

templates/systemd-mount.j2

@@ -1,9 +1,9 @@
 # {{ ansible_managed }}
 
 [Unit]
-Description=Auto mount for {{ item.where | default(item.what) }}
+Description=Auto mount for {{ systemd_mount_item }}
 
-[{{ (item.type == 'swap') | ternary('Swap', 'Mount') }}]
+[{{ systemd_mount_suffix | capitalize }}]
 What={{ item.what }}
 {% if item.type == 'swap' %}
 Priority={{ item.priority | default(0) }}

vars/main.yml

@@ -0,0 +1,21 @@
+---
+# Copyright 2018, 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.
+
+systemd_mount_states:
+  reloaded: reload
+  restarted: reload-or-restart
+  started: reload-or-restart
+  stopped: stopped
+  absent: stopped