[wak327]

Fixes #143

When MicroOVN isn't used, MicroCloud falls back to the Ubuntu fan (lxdfan0 with bridge.mode=fan), which needs the vxlan kernel module. On systems without that module, for example some Raspberry Pi kernels, creating the fan network fails after initialization:

Error: Failed adding link: Failed to run: ip link add name lxdfan0-fan type vxlan ...: exit status 2 (Error: Unknown device type.)

This adds the vxlan kernel module to the software requirements, as a hint for users who run into this. How to provide the module is left to the user, since it depends on the platform.

Checklist

• I have read the contributing guidelines and attest that all commits in this PR are signed off, cryptographically signed, and follow this project's commit structure.
• I have checked and added or updated relevant documentation.

[wak327]

@roosterfish @elijahgreenstein a small docs addition, could you take a look when you have a moment?

[elijahgreenstein]

@wak327 thank you for your contribution. While you've provided useful details in this PR, my preference would be to provide general requirements in the documentation (in this case the vxlan kernel module) and leave it to users to determine how to meet those requirements. See my comment below.

[wak327]

@roosterfish following @elijahgreenstein's suggestion, this now only adds the vxlan kernel module requirement to the software requirements, without the Raspberry Pi specific steps. Could you take a look?

[elijahgreenstein]

LGTM

[wak327]

@roosterfish thanks for the review, I've addressed your comments. Could you take another look?

[elijahgreenstein]

LGTM

[wak327]

@elijahgreenstein @roosterfish I applied the latest suggestions. Could you take another look?

[roosterfish]

@elijahgreenstein is it "on Ubuntu Fan" or "on the Ubuntu Fan"? I would guess the first.

[elijahgreenstein]

@roosterfish -- I don't think there's clear standard here, since I haven't seen that much writing on "the Ubuntu Fan" in other documentation or Ubuntu/Canonical pages. Elsewhere in the MicroCloud docs, though, we have "fall back on the Ubuntu Fan" (alternatives), and in the LXD docs on networking setups, we have "possibly in connection with the Ubuntu Fan," which links to an old video titled "Easy overlay networking in LXD with the Ubuntu Fan". Given that, I think we can leave the definite article in, as "on the Ubuntu Fan." If you prefer "on Ubuntu Fan", though, I'm not opposed to updating elsewhere in the docs too.