Managing Application Daemons
You manage application daemons (services) in Cumulus Linux in the following ways:
- Identifying active listener ports
- Identifying daemons currently active or stopped
- Identifying boot time state of a specific daemon
- Disabling or enabling a specific daemon
Using systemd and the systemctl Command
In general, you manage services using systemd via the systemctl
command. You use it with any service on the switch to
start/stop/restart/reload/enable/disable/reenable or get the status of
the service.
cumulus@switch:~$ sudo systemctl start | stop | restart | status | reload | enable | disable | reenable SERVICENAME.service
For example to restart networking, run the command:
cumulus@switch:~$ sudo systemctl restart networking.service
Unlike the service command in Debian Wheezy, the service name is
written after the systemctl subcommand, not before it.
Understanding the systemctl Subcommands
systemctl has a number of subcommands that perform a specific
operation on a given daemon.
- status: Returns the status of the specified daemon.
- start: Starts the daemon.
- stop: Stops the daemon.
- restart: Stops, then starts the daemon, all the while
maintaining state. So if there are dependent services or services
that mark the restarted service as Required, the other services
also get restarted. For example, running
systemctl restart frr.servicerestarts any of the routing protocol daemons that are enabled and running, such asbgpdorospfd. - reload: Reloads a daemon’s configuration.
- enable: Enables the daemon to start when the system boots, but
does not start it unless you use the
systemctl start SERVICENAME.servicecommand or reboot the switch. - disable: Disables the daemon, but does not stop it unless you
use the
systemctl stop SERVICENAME.servicecommand or reboot the switch. A disabled daemon can still be started or stopped. - reenable: Disables, then enables a daemon. You might need to do this so that any new Wants or WantedBy lines create the symlinks necessary for ordering. This has no side effects on other daemons.
Ensuring a Service Starts after Multiple Restarts
By default, systemd is configured to try to restart a particular
service only a certain number of times within a given interval before
the service fails to start at all. The settings for this are stored in
the service script. The settings are StartLimitInterval (which
defaults to 10 seconds) and StartBurstLimit (which defaults to 5
attempts), but many services override these defaults, sometimes with
much longer times. switchd.service, for example, sets
StartLimitInterval=10m and StartBurstLimit=3, which means if you
restart switchd more than 3 times in 10 minutes, it will not start.
When the restart fails for this reason, a message similar to the following appears:
Job for switchd.service failed. See 'systemctl status switchd.service' and 'journalctl -xn' for details.
And systemctl status switchd.service shows output similar to:
Active: failed (Result: start-limit) since Thu 2016-04-07 21:55:14 UTC; 15s ago
To clear this error, run systemctl reset-failed switchd.service. If
you know you are going to restart frequently (multiple times within the
StartLimitInterval), you can run the same command before you issue the
restart request. This also applies to stop followed by start.
Keeping systemd Services from Hanging after Starting
If you start, restart or reload any systemd service that could be
started from another systemd service, you must use the --no-block
option with systemctl. Otherwise, that service or even the switch
itself may hang after starting or restarting.
Identifying Active Listener Ports for IPv4 and IPv6
You can identify the active listener ports under both IPv4 and IPv6
using the netstat command:
cumulus@switch:~$ sudo netstat -nlp --inet --inet6
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:53 0.0.0.0:* LISTEN 444/dnsmasq
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 874/sshd
tcp6 0 0 :::53 :::* LISTEN 444/dnsmasq
tcp6 0 0 :::22 :::* LISTEN 874/sshd
udp 0 0 0.0.0.0:28450 0.0.0.0:* 839/dhclient
udp 0 0 0.0.0.0:53 0.0.0.0:* 444/dnsmasq
udp 0 0 0.0.0.0:68 0.0.0.0:* 839/dhclient
udp 0 0 192.168.0.42:123 0.0.0.0:* 907/ntpd
udp 0 0 127.0.0.1:123 0.0.0.0:* 907/ntpd
udp 0 0 0.0.0.0:123 0.0.0.0:* 907/ntpd
udp 0 0 0.0.0.0:4784 0.0.0.0:* 909/ptmd
udp 0 0 0.0.0.0:3784 0.0.0.0:* 909/ptmd
udp 0 0 0.0.0.0:3785 0.0.0.0:* 909/ptmd
udp6 0 0 :::58352 :::* 839/dhclient
udp6 0 0 :::53 :::* 444/dnsmasq
udp6 0 0 fe80::a200:ff:fe00::123 :::* 907/ntpd
udp6 0 0 ::1:123 :::* 907/ntpd
udp6 0 0 :::123 :::* 907/ntpd
udp6 0 0 :::4784 :::* 909/ptmd
udp6 0 0 :::3784 :::* 909/ptmd
Identifying Daemons Currently Active or Stopped
To determine which daemons are currently active or stopped, run
cl-service-summary:
cumulus@switch:~$ cl-service-summary
Service cron enabled active
Service ssh enabled active
Service syslog enabled active
Service neighmgrd enabled active
Service clagd enabled active
Service lldpd enabled active
Service mstpd enabled active
Service poed inactive
Service portwd inactive
Service ptmd enabled active
Service pwmd enabled active
Service smond enabled active
Service switchd enabled active
Service vxrd disabled inactive
Service vxsnd disabled inactive
Service bgpd disabled inactive
Service isisd disabled inactive
Service ospf6d disabled inactive
Service ospfd disabled inactive
Service rdnbrd disabled inactive
Service ripd disabled inactive
Service ripngd disabled inactive
Service zebra disabled inactive
You can also run systemctl list-unit-files --type service to list all
services on the switch and see which ones are enabled:
Click here to see output of this command ...
cumulus@switch:~$ systemctl list-unit-files --type service
UNIT FILE STATE
aclinit.service enabled
acltool.service enabled
acpid.service disabled
arp_refresh.service enabled
auditd.service enabled
autovt@.service disabled
bootlog.service enabled
bootlogd.service masked
bootlogs.service masked
bootmisc.service masked
checkfs.service masked
checkroot-bootclean.service masked
checkroot.service masked
clagd.service enabled
clcmd.service enabled
console-getty.service disabled
console-shell.service disabled
container-getty@.service static
cron.service enabled
cryptdisks-early.service masked
cryptdisks.service masked
cumulus-aclcheck.service static
cumulus-core.service static
cumulus-fastfailover.service enabled
cumulus-firstboot.service disabled
cumulus-platform.service enabled
cumulus-support.service static
dbus-org.freedesktop.hostname1.service static
dbus-org.freedesktop.locale1.service static
dbus-org.freedesktop.login1.service static
dbus-org.freedesktop.machine1.service static
dbus-org.freedesktop.timedate1.service static
dbus.service static
debian-fixup.service static
debug-shell.service disabled
decode-syseeprom.service static
dhcpd.service disabled
dhcpd6.service disabled
dhcpd6@.service disabled
dhcpd@.service disabled
dhcrelay.service enabled
dhcrelay6.service disabled
dhcrelay6@.service disabled
dhcrelay@.service disabled
dm-event.service disabled
dns-watcher.service disabled
dnsmasq.service enabled
emergency.service static
fuse.service masked
getty-static.service static
getty@.service enabled
halt-local.service static
halt.service masked
heartbeat-failed@.service static
hostname.service masked
hsflowd.service enabled
hsflowd@.service enabled
hwclock-save.service enabled
hwclock.service masked
hwclockfirst.service masked
ifup@.service static
initrd-cleanup.service static
initrd-parse-etc.service static
initrd-switch-root.service static
initrd-udevadm-cleanup-db.service static
killprocs.service masked
kmod-static-nodes.service static
kmod.service static
ledmgrd.service enabled
lldpd.service enabled
lm-sensors.service enabled
lvm2-activation-early.service enabled
lvm2-activation.service enabled
lvm2-lvmetad.service static
lvm2-monitor.service enabled
lvm2-pvscan@.service static
lvm2.service disabled
module-init-tools.service static
motd.service masked
mountall-bootclean.service masked
mountall.service masked
mountdevsubfs.service masked
mountkernfs.service masked
mountnfs-bootclean.service masked
mountnfs.service masked
mstpd.service enabled
netd.service enabled
netq-agent.service disabled
networking.service enabled
ntp.service enabled
ntp@.service disabled
openvswitch-vtep.service disabled
phy-ucode-update.service enabled
portwd.service enabled
procps.service static
ptmd.service enabled
pwmd.service enabled
frr.service enabled
quotaon.service static
rc-local.service static
rc.local.service static
rdnbrd.service disabled
reboot.service masked
rescue.service static
rmnologin.service masked
rsyslog.service enabled
screen-cleanup.service masked
sendsigs.service masked
serial-getty@.service disabled
single.service masked
smond.service enabled
snmpd.service disabled
snmpd@.service disabled
snmptrapd.service disabled
snmptrapd@.service disabled
ssh.service enabled
ssh@.service disabled
sshd.service enabled
stop-bootlogd-single.service masked
stop-bootlogd.service masked
stopssh.service enabled
sudo.service disabled
switchd-diag.service static
switchd.service enabled
syslog.service enabled
sysmonitor.service static
systemd-ask-password-console.service static
systemd-ask-password-wall.service static
systemd-backlight@.service static
systemd-binfmt.service static
systemd-fsck-root.service static
systemd-fsck@.service static
systemd-halt.service static
systemd-hibernate.service static
systemd-hostnamed.service static
systemd-hybrid-sleep.service static
systemd-initctl.service static
systemd-journal-flush.service static
systemd-journald.service static
systemd-kexec.service static
systemd-localed.service static
systemd-logind.service static
systemd-machined.service static
systemd-modules-load.service static
systemd-networkd-wait-online.service disabled
systemd-networkd.service disabled
systemd-nspawn@.service disabled
systemd-poweroff.service static
systemd-quotacheck.service static
systemd-random-seed.service static
systemd-readahead-collect.service disabled
systemd-readahead-done.service static
systemd-readahead-drop.service disabled
systemd-readahead-replay.service disabled
systemd-reboot.service static
systemd-remount-fs.service static
systemd-resolved.service disabled
systemd-rfkill@.service static
systemd-setup-dgram-qlen.service static
systemd-shutdownd.service static
systemd-suspend.service static
systemd-sysctl.service static
systemd-timedated.service static
systemd-timesyncd.service disabled
systemd-tmpfiles-clean.service static
systemd-tmpfiles-setup-dev.service static
systemd-tmpfiles-setup.service static
systemd-udev-settle.service static
systemd-udev-trigger.service static
systemd-udevd.service static
systemd-update-utmp-runlevel.service static
systemd-update-utmp.service static
systemd-user-sessions.service static
udev-finish.service static
udev.service static
umountfs.service masked
umountnfs.service masked
umountroot.service masked
update-ports.service enabled
urandom.service static
user@.service static
uuidd.service static
vboxadd-service.service enabled
vboxadd-x11.service enabled
vboxadd.service enabled
vxrd.service disabled
vxsnd.service disabled
wd_keepalive.service enabled
x11-common.service masked
ztp-init.service enabled
ztp.service disabled
191 unit files listed.
lines 147-194/194 (END)
Identifying Essential Services
If you need to know which services are required to run when the switch boots, run:
cumulus@switch:~$ sudo systemctl list-dependencies --before basic.target
To see which services are needed for networking, run:
cumulus@switch:~$ sudo systemctl list-dependencies --after network.target network.target ● ├─networking.service ● ├─switchd.service ● ├─wd_keepalive.service ● └─network-pre.target
To identify the services needed for a multi-user environment, run:
cumulus@leaf01:~$ sudo systemctl list-dependencies --before multi-user.target multi-user.target ● ├─bootlog.service ● ├─systemd-readahead-done.service ● ├─systemd-readahead-done.timer ● ├─systemd-update-utmp-runlevel.service ● └─graphical.target ● └─systemd-update-utmp-runlevel.service