Switch SESSION_ENGINE to memcached

Previously we were using cached_db session backend by default.
However with django version update, it requires more recent
mysqlclient module which is not part of requirements.
Moreover usage of cached_db makes us to carry and maintain
extra stuff, which can be dropped with memcached backend.

Change-Id: I8df7ee967d8dcbeb09a42fd568f98acc3e88adad

defaults/main.yml

@@ -128,18 +128,14 @@ horizon_system_user_home: "/var/lib/{{ horizon_system_user_name }}"
 ## Service Type and Data
 horizon_service_region: RegionOne
 horizon_service_name: horizon
-
-## Database info
-horizon_db_setup_host: "{{ ('galera_all' in groups) | ternary(groups['galera_all'][0], 'localhost') }}"
-horizon_galera_address: "{{ galera_address | default('127.0.0.1') }}"
-horizon_galera_database: dash
-horizon_galera_user: dash
-horizon_galera_use_ssl: "{{ galera_use_ssl | default(False) }}"
-horizon_galera_ssl_ca_cert: "{{ galera_ssl_ca_cert | default('/etc/ssl/certs/galera-ca.pem') }}"
-
 ## Session configuration
 # Specifies the timespan in seconds inactivity, until a user is considered as
 # logged out
+horizon_session_engine: 'django.contrib.sessions.backends.cache'
+horizon_session_caches:
+  default:
+    BACKEND: 'django.core.cache.backends.memcached.MemcachedCache'
+    LOCATION: "{{ memcached_servers.split(',') }}"
 horizon_session_timeout: 1800
 
 ## Horizon Help URL Path
@@ -393,7 +389,6 @@ horizon_listen_ports:
 
 horizon_pip_packages:
   - horizon
-  - PyMySQL
   - python-memcached
 
 # Specific pip packages provided by the user

releasenotes/notes/session_engine-54753c41d355e34e.yaml

@@ -0,0 +1,11 @@
+---
+upgrade:
+  - |
+    `SESSION_ENGINE` has been changed to memcached by default. So that
+    horizon do not require it's own database for storing session
+    information anymore. `horizon_galera_*` variables has no effect now.
+features:
+  - |
+    Added variables `horizon_session_engine` and `horizon_session_caches`
+    which can be used to configure horizon session engine and a backend
+    for it.

tasks/db_setup.yml

@@ -1,42 +0,0 @@
----
-# Copyright 2019, VEXXHOST, 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.
-
-# WARNING:
-# This file is maintained in the openstack-ansible-tests repository.
-# https://git.openstack.org/cgit/openstack/openstack-ansible-tests/tree/sync/tasks/db_setup.yml
-# If you need to modify this file, update the one in the openstack-ansible-tests
-# repository. Once it merges there, the changes will automatically be proposed to
-# all the repositories which use it.
-
-- name: Setup Database Service (MariaDB)
-  delegate_to: "{{ _oslodb_setup_host }}"
-  tags:
-    - common-mariadb
-  block:
-    - name: Create database for service
-      mysql_db:
-        name: "{{ item.name }}"
-      loop: "{{ _oslodb_databases }}"
-      no_log: true
-
-    - name: Grant access to the database for the service
-      mysql_user:
-        name: "{{ item.1.username }}"
-        password: "{{ item.1.password }}"
-        host: "{{ item.1.host | default('%') }}"
-        priv: "{{ item.0.name }}.*:{{ item.1.priv | default('ALL') }}"
-        append_privs: yes
-      loop: "{{ _oslodb_databases | subelements('users') }}"
-      no_log: true

tasks/horizon_db_sync.yml

@@ -1,29 +0,0 @@
----
-# Copyright 2014, 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: Perform a horizon DB sync
-  command: "{{ horizon_manage }} migrate --noinput"
-  become: yes
-  become_user: "{{ horizon_system_user_name }}"
-  changed_when: false
-
-- name: Register DB session cleanup cron
-  cron:
-    name: "Clear out expired sessions"
-    minute: "{{ 58 | random(seed=inventory_hostname, start=2) }}"
-    hour: "21"
-    job: "{{ horizon_manage }} clearsessions"
-    user: "{{ horizon_system_user_name }}"
-    state: present

tasks/horizon_post_install.yml

@@ -119,3 +119,13 @@
   register: async_compress_static_files
   async: 600
   poll: 0
+
+- name: Register DB session cleanup cron
+  cron:
+    name: "Clear out expired sessions"
+    minute: "{{ 58 | random(seed=inventory_hostname, start=2) }}"
+    hour: "21"
+    job: "{{ horizon_manage }} clearsessions"
+    user: "{{ horizon_system_user_name }}"
+    state: present
+  when: inventory_hostname == ansible_play_hosts[0]

tasks/main.yml

@@ -39,19 +39,6 @@
   tags:
     - always
 
-- import_tasks: db_setup.yml
-  when: inventory_hostname == ansible_play_hosts[0]
-  vars:
-    _oslodb_setup_host: "{{ horizon_db_setup_host }}"
-    _oslodb_databases:
-      - name: "{{ horizon_galera_database }}"
-        users:
-          - username: "{{ horizon_galera_user }}"
-            password: "{{ horizon_container_mysql_password }}"
-  tags:
-    - common-db
-    - horizon-config
-
 - import_tasks: horizon_pre_install.yml
   tags:
     - horizon-install
@@ -64,11 +51,6 @@
   tags:
     - horizon-config
 
-- import_tasks: horizon_db_sync.yml
-  when: inventory_hostname == ansible_play_hosts[0]
-  tags:
-    - horizon-config
-
 - import_tasks: horizon_ssl_self_signed.yml
   when:
     - horizon_enable_ssl | bool

templates/horizon-manage.py.j2

@@ -13,11 +13,8 @@
 # under the License.
 
 import os
-import pymysql
 import sys
 
-pymysql.install_as_MySQLdb()
-
 from django.core.management import execute_from_command_line  # noqa
 
 if __name__ == "__main__":

templates/horizon_django.wsgi.j2

@@ -1,12 +1,9 @@
 import logging
 import os
-import pymysql
 import sys
 from django.core.wsgi import get_wsgi_application
 from django.conf import settings
 
-pymysql.install_as_MySQLdb()
-
 # Add this file path to sys.path in order to import settings
 sys.path.insert(0, os.path.normpath(os.path.join(os.path.dirname(os.path.realpath(__file__)), '../..')))
 os.environ['DJANGO_SETTINGS_MODULE'] = 'openstack_dashboard.settings'

templates/horizon_local_settings.py.j2

@@ -1,6 +1,5 @@
 # -*- coding: utf-8 -*-
 import os
-import pymysql
 
 from django.utils.translation import ugettext_lazy as _
 
@@ -9,8 +8,6 @@ from horizon.utils import secret_key
 from openstack_dashboard import exceptions
 from openstack_dashboard.settings import HORIZON_CONFIG
 
-pymysql.install_as_MySQLdb()
-
 DEBUG = {{ debug }}
 TEMPLATE_DEBUG = DEBUG
 
@@ -142,28 +139,10 @@ SECRET_KEY = secret_key.generate_or_read_from_file(
 # We recommend you use memcached for development; otherwise after every reload
 # of the django development server, you will have to login again. To use
 # memcached set CACHES to something like
-CACHES = {
-    'default': {
-        'BACKEND': 'django.core.cache.backends.memcached.MemcachedCache',
-        'LOCATION': {{ memcached_servers.split(',') }}
-    }
-}
+CACHES = {{ horizon_session_caches }}
 
 # Set the session engine configuration:
-SESSION_ENGINE = "django.contrib.sessions.backends.cached_db"
-DATABASES = {
-    'default': {
-        'ENGINE': 'django.db.backends.mysql',
-        'HOST': '{{ horizon_galera_address }}',
-        'NAME': '{{ horizon_galera_database }}',
-        'USER': '{{ horizon_galera_user }}',
-        'PASSWORD': '{{ horizon_container_mysql_password }}',
-        'default-character-set': 'utf8'
-        {% if horizon_galera_use_ssl | bool -%}
-        ,'ssl-ca': '{{ horizon_galera_ssl_ca_cert }}'
-        {% endif -%}
-    },
-}
+SESSION_ENGINE = '{{ horizon_session_engine }}'
 
 # Send email to the console by default
 EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend'

vars/debian.yml

@@ -35,7 +35,6 @@ horizon_service_distro_packages:
   - python3-django-openstack-auth
   - python3-django-horizon
   - python3-memcache
-  - python3-pymysql
 
 horizon_apache_conf: "/etc/apache2/apache2.conf"
 horizon_apache_security_conf: "/etc/apache2/conf-available/security.conf"

vars/redhat-7.yml

@@ -42,7 +42,6 @@ horizon_service_distro_packages:
   - openstack-octavia-ui
   - python-django-horizon
   - python-memcached
-  - python-PyMySQL
 
 horizon_apache_conf: "/etc/httpd/conf/httpd.conf"
 horizon_apache_security_conf: "{{ horizon_apache_conf }}"

vars/suse.yml

@@ -43,7 +43,6 @@ horizon_service_distro_packages:
   - openstack-horizon-plugin-trove-ui
   - python-horizon
   - python-memcached
-  - python-PyMySQL
 
 # SUSE does not currently have packages for the following dashboards
 horizon_enable_heat_ui: False