KillMode=none is deprecated
We chaged systemd unit file killmode to none in https://github.com/ceph/ceph/pull/33162#issuecomment-584183316
Now we're getting a new warning:
Unit configured to use KillMode=none. This is unsafe, as it disables systemd's process lifecycle management for the service. Please update your service to use a safer KillMode=, such as 'mixed' or 'control-group'. Support for KillMode=none is deprecated and will eventually be removed.
#1 Updated by Sebastian Wagner 4 months ago
Answer by Valentin:
Hi Sebastian, feel free to ignore this warning. Systemd still supports KillMode=none but they decided to very slowly deprecate it. The reasons for that was that some third-party vendors somehow abused that setting which in turn caused problems during shutdown; some units just didn't want to die.
Starting with Podman v3.2 the units are using type=notify which changed many things but we found an alternative solution. Let me look it up quickly.
An alternative to KillMode=none is to remove that but add a high time out TimeoutStopSec=70. The reasoning behind is that we want to avoid between Podman and systemd trying to kill the container. We want Podman to do that, such that services have the chance to stop gracefully and that Podman can perform the necessary clean-up tasks.
type=notify is more systemd-idiomatic and what the systemd folks asked us to do in the future
Hope that helps.
Bottom line is: the warning is nothing to worry about for now. The systemd folks wanted to make it scary for the aforementioned reasons.