remove memcache entirely, add in some django redis to cover it's absence

CHANGELOG.md

@@ -3,6 +3,7 @@
 This is a list of high-level changes for each release of AWX. A full list of commits can be found at `https://github.com/ansible/awx/releases/tag/<version>`.
 
 ## 12.0.0 (TBD)
+- Removed memcached as a dependency of AWX (https://github.com/ansible/awx/pull/7240) 
 - Moved to a single container image build instead of separate awx_web and awx_task images. The container image is just `awx` (https://github.com/ansible/awx/pull/7228)
 - Official AWX container image builds now use a two-stage container build process that notably reduces the size of our published images (https://github.com/ansible/awx/pull/7017)
 - Removed support for HipChat notifications ([EoL announcement](https://www.atlassian.com/partnerships/slack/faq#faq-98b17ca3-247f-423b-9a78-70a91681eff0)); all previously-created HipChat notification templates will be deleted due to this removal.

CONTRIBUTING.md

@@ -157,7 +157,6 @@ If you start a second terminal session, you can take a look at the running conta
 $ docker ps
 CONTAINER ID        IMAGE                                              COMMAND                  CREATED             STATUS              PORTS                                                                                                                                                              NAMES
 44251b476f98        gcr.io/ansible-tower-engineering/awx_devel:devel   "/entrypoint.sh /bin…"   27 seconds ago      Up 23 seconds       0.0.0.0:6899->6899/tcp, 0.0.0.0:7899-7999->7899-7999/tcp, 0.0.0.0:8013->8013/tcp, 0.0.0.0:8043->8043/tcp, 0.0.0.0:8080->8080/tcp, 22/tcp, 0.0.0.0:8888->8888/tcp   tools_awx_run_9e820694d57e
-b049a43817b4        memcached:alpine                                   "docker-entrypoint.s…"   28 seconds ago      Up 26 seconds       0.0.0.0:11211->11211/tcp                                                                                                                                           tools_memcached_1
 40de380e3c2e        redis:latest                                       "docker-entrypoint.s…"   28 seconds ago      Up 26 seconds       0.0.0.0:6379->6379/tcp                                                                                                                                             tools_redis_1
 b66a506d3007        postgres:10                                        "docker-entrypoint.s…"   28 seconds ago      Up 26 seconds       0.0.0.0:5432->5432/tcp                                                                                                                                             tools_postgres_1
 ```

awx/settings/defaults.py

@@ -439,10 +439,11 @@ def IS_TESTING(argv=None):
 }
 
 # Django Caching Configuration
+DJANGO_REDIS_IGNORE_EXCEPTIONS = True
 CACHES = {
     'default': {
-        'BACKEND': 'django.core.cache.backends.memcached.MemcachedCache',
-        'LOCATION': 'unix:/var/run/memcached/memcached.sock'
+        'BACKEND': 'django_redis.cache.RedisCache',
+        'LOCATION': 'unix:/var/run/redis/redis.sock?db=1'
     },
 }
 

docs/clustering.md

@@ -218,7 +218,6 @@ Each Tower instance is made up of several different services working collaborati
 * **Callback Receiver** - Receives job events that result from running Ansible jobs.
 * **Celery** - The worker queue that processes and runs all jobs.
 * **Redis** - this is used as a queue for AWX to process ansible playbook callback events.
-* **Memcached** - A local caching service for the instance it lives on.
 
 Tower is configured in such a way that if any of these services or their components fail, then all services are restarted. If these fail sufficiently (often in a short span of time), then the entire instance will be placed offline in an automated fashion in order to allow remediation without causing unexpected behavior.
 

docs/licenses/django-redis.txt

@@ -0,0 +1,26 @@
+Copyright (c) 2011-2016 Andrey Antukh <niwi@niwi.nz>
+Copyright (c) 2011 Sean Bleier
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+3. The name of the author may not be used to endorse or promote products
+   derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.