networkd: make sure VXLAN is in the right section (LP: #2000713)

[daniloegea]

If an interface has a list of routes and is linked to a vxlan, the VXLAN keyword is added to the [Route] section in the resulting networkd configuration file.

This change makes the vxlan handling to happen before routes so VXLAN= will be added to the [Network] section.

It fixes LP#2000713

Description

Can be reproduced with:

network:
  renderer: networkd
  ethernets:
    eth0:
      routes:
        - to: 10.20.30.40/32
          via: 10.20.30.1
  tunnels:
    vxlan1:
      mode: vxlan
      id: 1
      link: eth0

This is the current output. The VXLAN= keyword was added to the [Route] section.

$ cat fakeroot/run/systemd/network/10-netplan-eth0.network
[Match]
Name=eth0

[Network]
LinkLocalAddressing=ipv6

[Route]
Destination=10.20.30.40/32
Gateway=10.20.30.1
VXLAN=vxlan1

This is the result with this patch:

[Match]
Name=eth0

[Network]
LinkLocalAddressing=ipv6
VXLAN=vxlan1

[Route]
Destination=10.20.30.40/32
Gateway=10.20.30.1

Checklist

• Runs make check successfully.
• Retains 100% code coverage (make check-coverage).
• New/changed keys in YAML format are documented.
• (Optional) Adds example YAML for new feature.
• (Optional) Closes an open bug in Launchpad.

[slyon]

Thanks, lgtm.
I've added some bits to make use of the ND_EMPTY and ND_VXLAN matching templates in your test case, in order to reduce the code/diff size a bit.

[slyon]

Just as a note to self: In the future, we want to switch to using GLib's g_key_file_set_* function to build that networkd ini files (similar to how we're doing it in nm.c nowadays). This should avoid errors such as this one.