DESCRIPTION OF PROBLEM:

  When building a simple Type=notify service, using python to write directly to the sd_notify socket works; however, using the systemd-notify wrapper command to send READY=1 fails. 


VERSION-RELEASE NUMBER OF SELECTED COMPONENT (IF APPLICABLE):

  [root@r73beta ~]# rpm -qa systemd\*
  systemd-219-26.el7.x86_64
  systemd-sysv-219-26.el7.x86_64
  systemd-libs-219-26.el7.x86_64
  systemd-python-219-26.el7.x86_64

  I tested this on both RHEL 7.2 and RHEL 7.3beta.
  
  
HOW REPRODUCIBLE:

  100%
  
  
STEPS TO REPRODUCE:

1. Create service unit

  [root@r73beta ~]# cat /etc/systemd/system/zz.service
  [Unit]
  Description=Test that systemd-notify works

  [Service]
  Type=notify
  ExecStart=/usr/local/sbin/zz.sh
  TimeoutStartSec=1
  StartLimitInterval=0
  NotifyAccess=all

  [Install]
  WantedBy=multi-user.target

2. Create ExecStart script

  [root@r73beta ~]# cat /usr/local/sbin/zz.sh
  #!/bin/bash
  systemd-notify --status="zz service up and running"
  systemd-notify --ready
  sleep 9d
  
  [root@r73beta ~]# chmod +x /usr/local/sbin/zz.sh

3. Reload daemon and try to start

  [root@r73beta ~]# systemctl daemon-reload
  [root@r73beta ~]# systemctl start zz
  Job for zz.service failed because a timeout was exceeded. See "systemctl status zz.service" and "journalctl -xe" for details.
  [root@r73beta ~]# while :; do systemctl restart zz &>/dev/null && printf . || printf X; done
  XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX^C


ADDITIONAL INFO:

* The short TimeoutStartSec=1 is just to make testing easier. This is an unloaded system so it's not like the message queue is getting backed up. It still doesn't work if I wait for 20s every time.

* Using "systemd-notify READY=1" instead of --ready makes no difference.

* The same test always succeeds in Fedora 24 with systemd-229-15.fc24 (though I have to move StartLimitInterval=0 to the [Unit] section of course).

* Using python to talk directly to the socket, all is well:

  [root@r73beta ~]# sed -i '/ExecStart/s/sh/py/' /etc/systemd/system/zz.service
  [root@r73beta ~]# systemctl daemon-reload
  [root@r73beta ~]# cat /usr/local/sbin/zz.py 
  #!/bin/python2
  import socket
  from os import getenv
  from time import sleep
  s = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
  e = getenv('NOTIFY_SOCKET')
  s.connect(e)
  s.sendall("READY=1")
  s.close()
  sleep(900)
  [root@r73beta ~]# chmod +x /usr/local/sbin/zz.py
  [root@r73beta ~]# systemctl start zz
  [root@r73beta ~]# while :; do systemctl restart zz &>/dev/null && printf . || printf X; done
  .............................................................................^C