title: redis service fails with permission denied on append file
body: <p>My redis service (installed from source) fails with this message in <code>/var/log/redis.log</code></p>
  
  <pre><code>2309:C 16 Mar 2019 20:16:10.633 # Redis version=5.0.3, bits=64, commit=00000000, modified=0, pid=2309, just started
  2309:C 16 Mar 2019 20:16:10.633 # Configuration loaded
  2311:M 16 Mar 2019 20:16:10.634 # Can't open the append-only file: Permission denied
  </code></pre>
  
  <p><strong>However</strong>:</p>
  
  <pre><code>root@redis:~# sudo su - redis
  redis@redis:~$ touch /var/lib/redis/foobar.txt
  redis@redis:~$ echo $?
  0
  </code></pre>
  
  <p>Here is my <code>/etc/redis.conf</code></p>
  
  <pre><code>root@redis:~# cat /etc/redis.conf 
  cluster-enabled yes
  cluster-config-file nodes.conf
  cluster-node-timeout 5000
  appendonly yes
  dir /var/lib/redis
  daemonize yes
  logfile "/var/log/redis.log"
  </code></pre>
  
  <p>and here is my custom unit file for redis</p>
  
  <pre><code>root@redis:~# cat /etc/systemd/system/redis.service 
  Description=Redis In-Memory Data Store                       
  After=network.target                                         
  
  [Service]                                                    
  Type=forking                                                 
  User=redis                                                   
  Group=redis                                                                                
  PermissionsStartOnly=true                                                              
  ExecStop=/bin/kill -s TERM $MAINPID
  PIDFile=/var/run/redis/redis-server.pid
  ExecStart=/opt/redis-stable/src/redis-server /etc/redis.conf
  Restart=always                                               
  RestartSec=3                                                 
  LimitNOFILE=65535
  ReadWriteDirectories=-/var/lib/redis
  ReadOnlyDirectories=/
  ReadWriteDirectories=-/var/lib/redis
  ReadWriteDirectories=-/var/log/redis
  ReadWriteDirectories=-/var/run/redis
  
  
  
  [Install]                                                    
  WantedBy=multi-user.target  
  </code></pre>