nspawn: Support multiple virtual Enternet links (veth)

[niklutz]

Submission type

• Bug report
• Request for enhancement (RFE)

Current situation

Its simple to create a container with a single veth using --network-veth and --network-bridge.
Adding a second interfaces requires a lot of scripting since --network-veth-extra requires the interface to exist (and does not add it to a bridge).

Question

• Since nspawn already knows how to create veths (adding it to a bridge, removing it when the container stops, ...) makes me wonder if there are any plans to support multiple veths? (I dont like the idea of duplicating this functionality in scripts)
• Would you accept a patch, and if yes:
  • Extending --network-veth to accept optional arguments (like myveth1, myveth2) and extending --network-bridge to accept multiple bridges might break current users since the "-n" option would disappear (would it?) - is this acceptable or should an additonal option be added?

Possible implementation

• Get arguments in nspawn.c and loop calling setup_veth(..., idx)
• nspawn-network.c
  • add_veth should get an additional parameter idx
  • setup_veth should get an additional parameter idx

Am I missing something?

[poettering]

Hmm? I think this is a misunderstanding. --network-veth-extra= in fact will create a new veth pair each time you use it. It requires no extra scripting, it will add a completely new veth pair on its own. In fact if there's already some interface around by the name specified then the operation will fail.

(--network-interface= otoh is the switch to move an existing iface into the container, but that's something completely different...)

Closing, since what is being asked for already exists.