Support systemd-notify

[waltmck]

I have checked if others have suggested this already

• I have checked this issue tracker to see if others have reported similar issues.

Feature description

In order to use zerotier alongside mullvad, I am using the provided mullvad-daemon.service file to run Mullvad and the following service file to start Zerotier (with irrelevant parts excluded):

[Unit]
After=network.target mullvad-daemon.service

[Service]
ExecStart=mullvad-exclude zerotierone

Unfortunately, there is an intractable race condition between mullvad-daemon mounting the net_cls cgroup controller and mullvad-exclude trying to use this controller. On startup this manifests in zerotierone.service failing repeatedly with mullvad-exclude[PID]: No net_cls controller until the controller is actually mounted (or just failing if Restart= is not configured).

The idiomatic systemd solution to this is to use Type=notify, and for the daemon to issue a notification when it is finished setting up, that way services with an After= dependency can know when to start.

Alternative solutions

The only feasible alternative is to set Restart=always on services which depend on mullvad-exclude, which is undesirable as it needlessly slows down boot times.

Type of feature

• Better privacy/anonymity
• Better at circumventing censorship
• Easier to use
• Other

Operating System

• Android
• iOS
• Windows
• macOS
• Linux

[hulthe]

Thanks for digging into this and suggesting a solution, I'll add it to our backlog :)