Questions about Go initialization code for LXD client

votsalo · May 1, 2023, 3:37pm

I use the Go LXD Api, and so I’ve looked into how the “lxc” command creates an lxc.InstanceServer, in order to do the same.

In github.com/lxc/lxd, client/connection.go uses /var/lib/lxd/unix.socket as the default location for the unix socket, but when LXD is installed via the recommended snap, there is no such socket. The snap LXD socket is /var/snap/lxd/common/lxd/unix.socket.

Similarly with the user lxd config directory:
lxc/main.go uses path.Join(os.Getenv(“HOME”), “.config”, “lxc”)
But I find that the snap lxc command uses $HOME/snap/lxd/common/config/

I understand that the non-snap paths were used by the “lxc” command before LXD was a snap.

But why does the Go code still use the pre-snap paths?

pylxd uses both paths. I would expect the Go code to do the same.

Does the snap runtime environment map /var/lib/lxd/ to /var/snap/lxd/common/lxd/
and $HOME/.config/lxc/ to $HOME/snap/lxd/common/config/?

tomp · May 12, 2023, 1:02pm

We use this function:

github.com

lxc/lxd/blob/399e6794b2fdbd0821f64910202478f2e25a023f/shared/util.go#L177-L217

      
        
            func HostPath(path string) string {
            	// Ignore empty paths
            	if len(path) == 0 {
            		return path
            	}
            
            
	// Don't prefix stdin/stdout
            	if path == "-" {
            		return path
            	}
            
            
	// Check if we're running in a snap package
            	if !InSnap() {
            		return path
            	}
            
            
	// Handle relative paths
            	if path[0] != os.PathSeparator {
            		// Use the cwd of the parent as snap-confine alters our own cwd on launch
            		ppid := os.Getppid()

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To make the path relative to the snap if it detects its running inside a snap.