Created attachment 1106 [details] View of the Status->Licenses menu without crontab running the script. During the installation of ThinLinc server, there is no check for if crontab is installed. We depend on crontab for updating the license usage graphs in Web Admin, since we use it for running the script tl-collect-licensestats. Without the cronjob running, we get no graphs. See attachment.
The resulting error of not running the cronjob can be seen in /var/log/tlwebadm.log: ERROR: opening '/var/opt/thinlinc/statistics/users-licenses.rrd': No such file or directory The missing file users-licenses.rrd gets created by tl-collect-licensestats when it runs.
While crontab is not being deprecated in a strict sense, it looks like the more popular Linux distributions are moving away from it, in favor of more modern alternatives. The fact that crontab isn't installed by default on e.g. Fedora 39 Workstation can be interpreted as a sign of this, and since we want to keep with the times, it is now also time for us to do the same move.
One alternative forward could be to add crontab and (or) anacron a requirement when installing the ThinLinc server. But, continuing on comment 2, we also want to keep our dependencies at a minimum. This, to not risk breaking compatibility with future releases of our supported Linux distributions.
Another alternative is to use Systemd timers. It looks like it should be possible to use timers to achieve something that is equivalent to the crontab configuration that we are using today. But we will need to adjust our server install to set up the timer(s) we need, instead of just installing a cron-script to /etc. We are also already depending on Systemd, since it is a requirement for running our services. Using timers would therefore not require us to add yet another dependency to the installation.
Let's use a Systemd timer. We should mimic the behavior of the cronjob that is currently used. its config line looks like this: > */5 * * * * root <script name> This translates to "run <script name> as the user root every 5 minutes", so this is the goal of the new timer.
The syntax "*/5" actually does not signify every 5 minutes, but instead it means that, in the case of minutes, the script will run when the (wall) clock is at some time modulo 5. So e.g. the script will run 12:00, 12:05, 12:10, 12:15 etc. In a systemd timer this is equivalent to the directive: > OnCalendar=*:0/5 This isn't necessarily what we want. We just want to make sure that the license graphs are updated every 5 minutes, it isn't important that the update occurs at a specific time. Instead, we can use either of the two directives: > OnUnitActiveSec=5m > OnUnitInactiveSec=5m OnUnitActiveSec sets activation time relative to the start of a previous event, while OnUnitInactiveSec sets activation time relative to the end of a previous event. Since the script we are running to get updates runs quite fast, eihter one of these will likely work just fine.
I also noticed that since both OnUnitActiveSec and OnUnitInactiveSec are defined based on when their last trigger occured, we need to actually create an initial trigger for the timer sequence to start. This can be done by adding one of the two directives: > OnBootSec > OnActiveSec OnActiveSec will trigger an initial run of the corresponding service when the timer is first started. OnBootSec will trigger an initial run at some specified time after the system booted, or directly if this time has already passed when the timer is started.
We have decided to use the OnCalendar directive, since this is closes to what the old cron job did. It's also nice if the graphs generated have data points that are nicely placed on the graph grid, which seems to be aligned with hour timestamps.
The cron job we had for updating license stats has now been replaced with a Systemd timer that is running with equivalent scheduling, once every five minutes, starting at each hour. > e.g. 10:00, 10:05, 10:10, 10:15... etc.
Testing: ======== I have installed the server and run tl-setup on RHEL9 and Ubuntu 24.04 in both master and agent configuration. Master: ------- The timer is enabled and runs every 5 minutes Agent: ------ The timer is disabled. Uninstall of server: -------------------- The timer is removed regardless of server type.
