Upgrade to mysql 5.7, tag memcached 1.5, and check for PID 1 on workers instead of ps. ps generates apparmor errors in the docker daemon.

deploy/docker-compose-test.yml

@@ -42,7 +42,7 @@ services:
       test: curl --insecure https://127.0.0.1/
 
   db:
-    image: mysql:5.5
+    image: mysql:5.7
     ports:
       - "3306:3306"
     volumes:
@@ -82,7 +82,7 @@ services:
       caching:
     restart: always
     healthcheck:
-        test: ps -ef | grep rake | grep ruby
+        test: kill -0 1
     command: bundle exec rake jobs:work RAILS_ENV=production
     deploy:
       resources:
@@ -94,7 +94,7 @@ services:
           memory: 256M
 
   memcached:
-    image: memcached
+    image: memcached:1.5
     deploy:
       resources:
         limits: