use sysctl.d instead of /etc/sysctl.conf - #2857
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Ubuntu 26.04 ships neither /etc/sysctl.conf nor the /etc/sysctl.d/99-sysctl.conf -> ../sysctl.conf link that 24.04 has, and systemd-sysctl only reads sysctl.d at boot. The settings the scripts append to /etc/sysctl.conf (vm.overcommit_memory for Redis, vm.max_map_count for Elasticsearch, fs.inotify.max_user_watches for files_inotify) are therefore lost at the first reboot on 26.04. Write each setting to its own file in /etc/sysctl.d instead, which every Ubuntu release reads. On existing VMs where a script created /etc/sysctl.conf, the updater restores the 99-sysctl.conf link so that those settings (and any added by hand) apply again.
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On Ubuntu 26.04 the kernel settings the scripts save to
/etc/sysctl.confare never applied at boot:vm.overcommit_memory = 1for Redis, on every new VMvm.max_map_countfor Elasticsearch (Full Text Search)fs.inotify.max_user_watchesfor files_inotify (SMB mount, SMB server)Root cause: 24.04 ships
/etc/sysctl.confand the/etc/sysctl.d/99-sysctl.conf -> ../sysctl.conflink. 26.04 ships neither, and systemd-sysctl only readssysctl.d. The scripts create/etc/sysctl.conf, but nothing reads it.Fix:
/etc/sysctl.d/90-*.conf, which every Ubuntu release reads, and apply it right away.99-sysctl.conflink when/etc/sysctl.confexists without it, so settings older scripts (or admins) put there apply again.Existing installs: fixed by the next update. 24.04 VMs already have the link, so nothing changes there.
Verified on an Ubuntu 26.04 test container (fresh install of this branch):
/etc/sysctl.confis no longer created, andsystemd-analyze cat-config sysctl.dshows/etc/sysctl.d/90-redis.confwithvm.overcommit_memory = 1, also after a reboot./etc/sysctl.confline and no link,update.sh minorcreated/etc/sysctl.d/99-sysctl.conf -> ../sysctl.conf.🤖 AI (if applicable)
Assisted-by: ClaudeCode:claude-opus-5-5