D. J. Bernstein’s daemontools includes a service supervisor which ensures services it supervises are restarted should they ever stop due to a program/system error. Daemontoos is easy to install, and is best installed from FreeBSD’s ports system at /usr/ports/sysutils/daemontools. Be sure to also install the manual, which you can find in a sub-directory work/daemontools-man. The README file that can be found within instructs to [manually] install the manual entries using the command gzip *.8 ; cp *.8.gz /usr/share/man/man8/ (while residing in the daemontools-man directory). Once installed, there are few additional steps to do:
- Copy /usr/ports/sysutils/daemontools/work/svscan.sh.sample to
/usr/local/etc/rc.d/svscan.sh and give it owner execute privileges with
chmod 700 /usr/local/etc/rc.d/svscan.sh
- Create /var/service and create a symlink to it from /service
ln -s /var/service /service
- Add following to /etc/rc.conf:
#start /var/service scanning
- Reboot the system (svscan will *not* start on a BSD system before the system is rebooted)
Optionally you can also install Bruce Guenter’s supervise-scripts that make life a whole lot easier with daemontools’ supervise.
- Install latest bglibs if not yet installed
** bglibs is best to install from a downloaded tarball rather than from the ports (while the ports version installs the libs in a more logical location at /usr/local/lib/bglibs/ the programs that utilize the library (bcron, ucspi-unix, etc.) have difficulty locating it.** few symlinks are required (these refer to the locations bglibs installs itself when compiled from the tarball rather than from the ports):
/usr/local/bglibs -> /usr/local/lib/bglibs
/usr/local/bglibs/lib/libbg-sysdeps.so.2 -> /usr/local/lib/libbg-sysdeps.so.2
/usr/local/bglibs/lib/libbg.so.2 -> /usr/local/lib/libbg.so.2
- Download, compile, and install supervise-scripts. Once installed, you’ll find new commands svc-start, svc-stop, svc-restart, svc-add, svc-remove, svc-isdown, svc-isup, svc-waitdown, svc-waitup, and svc-status in /usr/local/bin. These make scripting and managing services much easier.
When switching programs to be svscan-started and svscan-managed, remember to make sure they’re not being started either as default services by the system, or that a prior startup setting doesn’t exist in /etc/rc.conf. Disable them (depending on the service) by commenting out the startup in /etc/rc.conf, by adding a “NO” clause in /etc/rc.conf (such as cron_enable=”NO”), or by disabling the corresponding startup script in /usr/local/etc/rc.d.
If you mess up a service initialization, uninstall the failed service (i.e. unlink the service’s primary service directory from /var/service), delete the “supervise” subfolders (and “down” file if present) from the service’s primary service directory (there’s one also in the “log” subfolder). Then reboot the system, and reinstall the service either by using the supervise-scripts command svc-add, or by simply symlinking the service’s primary service directory to /var/service (for example ln -s /var/db/mysql-supervise /var/service/mysql).