Why isn't my systemd service waiting for the network?

Question

Per this question and its answers, I've added the following to my service file:

Wants=network-online.target
After=docker.service network.target network-online.target

I've also run:

systemctl enable NetworkManager-wait-online.service
systemd-networkd-wait-online.service

And yet my ExecStartPre task which uses git pull origin master still fails because of what appears to be a connectivity issue.

Mar 22 16:17:21 COMPUTER git[1983]: ssh: Could not resolve hostname github.com: Name or service not known
Mar 22 16:17:21 COMPUTER git[1983]: fatal: Could not read from remote repository.

Am I missing something obvious? Is there another service I need to wait for in order to use git pull? (In case it's relevant, I'm using Ubuntu 16.10 and systemd 231.)

Answer 1

First step is to determine if you're using NetworkManager or systemd-networkd. Enable wait-online for the one you are using (assuming systemd-networkd for this example):

systemctl enable systemd-networkd-wait-online.service

Have your service start after the wait-online service:

[Unit]
...
After=systemd-networkd-wait-online.service
Requires=systemd-networkd-wait-online.service

(requires is a stricter variant of wants, in this case it seems like you want the hard dependency).

This should cause your service to start after the network is guaranteed up.

---

Alternatively (or in conjunction with the previous solution) you can configure the service to restart when it fails using the Restart= flag:

[Service]
...
Restart=on-failure
RestartSec=5

https://www.freedesktop.org/software/systemd/man/systemd.service.html#Restart=

This might be the better method, because it wont slow your boot (https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget/#cutthecraphowdoimakenetwork.targetworkforme - using wait-online is liable to slow your boot-time considerably), but if you're worried about what the service might do when it fails, go for option 1 or both.