Discovered root policy does not know about new bridges, filesystem changes

[reynir]

In #190 a discovered root policy was introduced. This examines the total disk space and what network bridges exist. This has the unfortunate effect that newly created bridges are not usable by albatross. On the other hand it has the positive effect that bridges that are created by other services that are launched after albatross are not usable by albatross, for example bridges created by libvirt or docker.

Similarly, this doesn't observe changes to the filesystem. Today, I created a 64 GB filesystem for /var/lib/albatross/block, but the root policy says 40 GB as is the size of the root filesystem.

[hannesm]

Thanks for your report. Yes, indeed, there are limitations. But I wonder what should be done... we can busily loop for detecting changes, but then if e.g. mollymawk is connected, it would as well busily need to gather the root policy...

With the current behaviour, albatross needs to be restarted if the bridges / file system changes.

[reynir]

I'm as well unsure what to do. One way could be to re-discover the root policy on every policy operation. I'm not sure I like that approach. It would also result in mollymawk having to do more queries to albatross.

Perhaps it is sufficient to just document this behavior.

[hannesm]

The question is not only what to do if block storage has increased in size / new network bridges are available, but as well what to do when block storage size gets decreased / bridges are removed?