Cronjob causing TCP_Timeout


I am using Gitlab 15.4.2-ce.0 on a Proxmox VM with Debian Bullseye 11. I am monitoring the availability of the Website with an active check in Checkmk. For those not familiar with Checkmk, it is using the Nagios plugin check_https. Every night at 0:06 Checkmk trows a TCP Timeout while connecting to the website. I tracked a similar problem in Matomo to a backup cron job with mysqldump which caused too much load. I think this is a similar problem, but the backup cronjob is running at 3AM, so it is not responsible. I assume the CE is running some kind of cronjobs. How can I check which cron jobs are running at 0:06 and most likely causing the timeout? I have already checked the all available system and user crontabs, but haven’t found any job which could be responsible. Where does the internal cron (I assume its go-cron, which I found via locate) keep its tab?

Yours sincerely


From your Gitlab instance in web browser, go to Admin → Monitoring → Background Jobs

Here you will find the Sidekiq interface, and view the cron jobs here that Gitlab uses.

I also use checkmk, but I don’t monitor with the tcp check, I integrated it using the nginx checkmk plugin and monitor port 8060 which is where Nginx is. In /etc/checkmk/nginx_status.cfg:

servers = [
		"address" : "localhost",
		"protocol" : "http",
		"port" : "8060",