Comment 1 for bug 1927549

> If I specify it during the deployment in the bundle the value is left empty.

Can you show us the bundle you're deploying, and where you're seeing the empty value?

> And if I configure it once the deployment is done with the juju config command, the value stays in the configuration but no operation are done on the nodes.

The charm has code to handle the iface config changing[1], and I've confirmed that code is present in flannel rev 514. What operation is not happening that you're expecting to see?

[1]: https://github.com/charmed-kubernetes/charm-flannel/blob/e541222bf746caea5884de99d4ff0472c138fe86/reactive/flannel.py#L141-L144