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Asked: 2015-07-12 04:11:58 +0800 CST

How can I make my systemd service wait for a network interface?

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I have an upstart script that I am converting to systemd. For this service to start, a certain network interface needs to be available.

This is what I am using in my upstart script:

start on (local-filesystems and net-device-added INTERFACE=tun0)

What's the systemd equivalent?

systemd

1 Answers

  1. See https://unix.stackexchange.com/questions/257888/systemd-wait-for-network-interface-to-be-up-before-running-service

    You should be able have a slightly broken version of what you had in the upstart script with something like:

    Wants=sys-devices-virtual-net-tun0.device
After=sys-devices-virtual-net-tun0.device

    systemd should generate the tun0 'device' file. The only problem is that if the tun0 device isn't created by openvpn quickly enough, your service start will try to 'start' sys-devices-virtual-net-tun0.device which will result in a timeout failure (by default specified by DefaultTimeoutStartSec as 90 seconds usually in /etc/systemd/system.conf). So it might be best to have something to depend on openvpn and then explicitly check for the tun0 device, restarting if it is not found:

    # Wait loosely on openvpn service
Wants=openvpnxxxx.service
After=openvpnxxx.service

# Make sure tun0 is up/active
ExecStartPre=/bin/bash -c "systemctl is-active sys-devices-virtual-net-tun0.device"
# Keep restarting till tun0 is up
Restart=on-failure
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