More robust per devenv host and network control

[ParetoOptimalDev]

I've been having an issue where hostctl sometimes doesn't work, but also clashes between active projects with same host names.

As mentioned in #940 it would be good to have something more robust.

I think I might have found that something... but it's unclear if this will work for devenv because I'm not sure what the scope of bwrap is. I think the processes would all need to be wrapped with this bwrap or proxc call that need modified networking, so it should work.

Use Linux's mount namespace to override /etc/resolv.conf with what you want. Bubblewrap is a good tool to do that, without root. bwrap --dev-bind / / --ro-bind-data {FD} /etc/resolv.conf

FD is the file descriptor that contains nameserver {the-dns-you-need}. Remember to make system's DNS cache unaccessable for your process (Plex server) (eg. bwrap --tmpfs /var/run/nscd/)

Whole command: bwrap --dev-bind / / --ro-bind-data {fd} /etc/resolv.conf --tmpfs /var/run/nscd/ sh -c "your command and arguments"

I wrote a bash script to do all the steps. Here you are

The mentioned bash script is at https://github.com/garywill/proxc#start-of-content

It uses bubblewrap to create a mount namespace, in which processes see the DNS you want in a fake /etc/resolv.conf.

It bans in the namespace /var/run/nscd so processes can't use system's DNS cache

However here there is also a downside:

Notice: If network status change, NetworkManager or other program may delete /etc/resolv.conf and create a new one. That makes bubblewrap's file binding lost, causing DNS fallback to original system's DNS

So the point of this issue then is:

• point out shortcomings of hostctl
• share a potential solution
• solicit other ideas on how to handle this problem of per devenv hosts/networking more robustly