PP-280: Introduce unit file for systems that supports systemd process management

PBS should support start up using systemd in supported platforms.

EDD

Interface1: Admin can use systemd to start and stop PBS services: 

• Visibility: Public
• Change Control: Stable
• Synopsis: Systemd can be used to start and stop PBS services on systems which supports systemd.
• Details: From 15.0 release, systemd commands can be used on supported systems.
  • Systems which supported systemd are: suse >=1210 and rhel >=7
  • sysvinit script will be still present in the same location, and this functionality is not deprecated.
    

    • Usage	sysvinit	alternative in systemd
      starting	/etc/init.d/pbs start	systemctl start pbs
      stopping	/etc/init.d/pbs stop	systemctl stop pbs
      status	/etc/init.d/pbs status	systemctl status pbs
      restart	/etc/init.d/pbs restart	systemctl restart pbs

    • The logs which are displayed in stdout from /etc/init.d/pbs are not displayed during systemd start up.
    • But these logs can be seen with systemctl status command.

      • [root@vbox pbspro]# systemctl status pbs
        ● pbs.service - Portable Batch System
        Loaded: loaded (/opt/pbs/default/libexec/pbs_init.d; enabled; vendor preset: disabled)
        Active: active (running) since Wed 2016-08-10 15:23:48 IST; 21h ago
        Docs: man:pbs(8)
        Process: 101261 ExecStart=/opt/pbs/default/libexec/pbs_init.d start start (code=exited, status=0/SUCCESS)
        CGroup: /system.slice/pbs.service
        ├─104185 /opt/pbs/default/sbin/pbs_comm
        ├─104229 /opt/pbs/default/sbin/pbs_mom
        ├─104267 /opt/pbs/default/sbin/pbs_sched
        ├─104582 /opt/pbs/default/sbin/pbs_ds_monitor monitor
        ├─104645 /opt/pbs/14.101/pgsql/bin/postgres -D /var/spool/PBS/datastore -p 15007
        ├─104648 postgres: logger process 
        ├─104651 postgres: checkpointer process 
        ├─104652 postgres: writer process 
        ├─104653 postgres: wal writer process 
        ├─104654 postgres: autovacuum launcher process 
        ├─104655 postgres: stats collector process 
        ├─104771 postgres: pbsdata pbs_datastore 192.168.153.140(44113) idle
        └─104772 /opt/pbs/default/sbin/pbs_server.bin

        Aug 10 15:23:44 vbox pbs_init.d[101261]: PBS sched
        Aug 10 15:23:44 vbox su[104295]: (to pbsdata) root on none
        Aug 10 15:23:44 vbox su[104357]: (to pbsdata) root on none
        Aug 10 15:23:45 vbox su[104446]: (to pbsdata) root on none
        Aug 10 15:23:45 vbox su[104510]: (to pbsdata) root on none
        Aug 10 15:23:45 vbox su[104583]: (to pbsdata) root on none
        Aug 10 15:23:48 vbox pbs_init.d[101261]: Connecting to PBS dataservice....connected to PBS dataservice@vbox
        Aug 10 15:23:48 vbox pbs_init.d[101261]: Licenses valid for 1000000 Floating hosts
        Aug 10 15:23:48 vbox pbs_init.d[101261]: PBS server
        Aug 10 15:23:48 vbox systemd[1]: Started Portable Batch System.

    • If the start up is failed the command will throw an error as follows - 

      • [root@vbox nithinj]# systemctl start pbs
        Job for pbs.service failed because the control process exited with error code. See "systemctl status pbs.service" and "journalctl -xe" for details.

    • "systemctl status pbs"  or "journalctl -u pbs" will lead to the specific reason behind the failure.
    • The following command can be used to start PBS using systemd after the installation - "systemctl daemon-reload && systemctl start pbs"
      daemon-reload is used to reload all systemd units if they got modified or newly added.
    • Possible Enhancements in future: We can convert start up script into C/C++ binary so that system start up will become more faster.
    • "systemctl enable pbs" This will enable PBS to be started on bootup.