Log files (/var/log/messages) written by rsyslog in RHEL7 are empty and logger commands do nothing

Issue

• rsyslog not writing to /var/log/messages in RHEL 7.

• On a RHEL 7 machine, the logger command does not generate a new log entry in /var/log/messages -- instead, it's empty except for messages from rsyslogd itself, e.g.:

  ~]# cat /var/log/messages
  Jan 26 11:32:45 r72 rsyslogd: [origin software="rsyslogd" swVersion="7.4.7" x-pid="1704" x-info="http://www.rsyslog.com"] rsyslogd was HUPed
  ~]# systemctl restart rsyslog
  ~]# logger testing testing
  ~]# cat /var/log/messages
  Jan 26 11:32:45 r72 rsyslogd: [origin software="rsyslogd" swVersion="7.4.7" x-pid="1704" x-info="http://www.rsyslog.com"] rsyslogd was HUPed
  Jan 26 11:33:10 r72 rsyslogd: [origin software="rsyslogd" swVersion="7.4.7" x-pid="1704" x-info="http://www.rsyslog.com"] exiting on signal 15.
  Jan 26 11:33:10 r72 rsyslogd: [origin software="rsyslogd" swVersion="7.4.7" x-pid="1792" x-info="http://www.rsyslog.com"] start
  

• On a RHEL 7 machine, the logger command generates new log entries in the systemd journal ...

  ~]# journalctl -fn0 &
  [1] 1884
  -- Logs begin at Tue 2016-01-26 10:26:17 EST. --
  ~]# logger testing logger
  Jan 26 11:38:42 r72.example.com root[1885]: testing logger
  

  However, the same messages are not showing up in rsyslog's /var/log/messages file.

  ~]# tail -fn0 /var/log/messages &
  [1] 1913
  ~]# logger testing logger again
  ~]#