juju deploy for lxd 2.0.x will fail with no config file found at /etc/default/lxd-bridge

[Simon Richardson]

When using lxd 2.0.x that doesn't support api network extensions, the latest juju will fail because it can't find the configuration file inside the container. Also note, the error message for this isn't ideal, in the fact the user can't actually do anything about this. Instead this is just juju not creating the file in the right location.

ERROR new environ: profile "default": no config file found at /etc/default/lxd-bridge
It looks like your LXD bridge has not yet been configured. Configure it via:

 sudo dpkg-reconfigure -p medium lxd

and run the command again.
2018-08-23 15:37:56 DEBUG cmd supercommand.go:459 error stack:
/home/simon/go/src/github.com/juju/juju/container/lxd/network.go:374: no config file found at /etc/default/lxd-bridge
It looks like your LXD bridge has not yet been configured. Configure it via:

 sudo dpkg-reconfigure -p medium lxd

and run the command again.
/home/simon/go/src/github.com/juju/juju/container/lxd/network.go:229:
/home/simon/go/src/github.com/juju/juju/container/lxd/network.go:125: profile "default"
/home/simon/go/src/github.com/juju/juju/provider/lxd/server.go:342:
/home/simon/go/src/github.com/juju/juju/provider/lxd/server.go:198:
/home/simon/go/src/github.com/juju/juju/provider/lxd/environ.go:65:
/home/simon/go/src/github.com/juju/juju/provider/lxd/provider.go:150:
/home/simon/go/src/github.com/juju/juju/cmd/jujud/bootstrap.go:147: new environ
2018-08-23 15:37:56 DEBUG juju.cmd.jujud main.go:196 jujud complete, code 0, err <nil>

[Simon Richardson (simonrichardson)]

We're missing the following in the latest juju https://github.com/juju/juju/blob/2.2/container/lxd/initialisation_linux.go#L179

[Simon Richardson (simonrichardson)]

A previous PR that was closed https://github.com/juju/juju/pull/8964 was almost half way to solving it. Resurrecting the idea from the PR should allow this to work.