Support non-default libvirt socket URLs and URI

On some systems, such as Fedora 40, there is no longer a "legacy"
/run/libvirt/libvirtd-sock. Instead, all the driver-specific daemons have
their own socket, such as /run/libvirt/virtqemud-sock.

So, let users specify the socket they want to use. While at it, also allow
them to chose different connection URIs, such as qemu:///session.

cmd/config.go

@@ -25,6 +25,14 @@ import (
 // configuration file.
 // The default config file also contains some inline documentation for each option.
 const defaultConfigTemplate = `[libvirt]
+# socket is the path to the unix domain socket for libvirt.
+# Default value: "{{ get "libvirt.socket" }}"
+socket = "{{ get "libvirt.socket" }}"
+
+# uri is the libvirt uri to connect to a specific driver.
+# Default value: "{{ get "libvirt.uri" }}"
+uri = "{{ get "libvirt.uri" }}"
+
 # pool is the libvirt pool that virter should use.
 # The user is responsible for ensuring that this pool exists and is active.
 # Default value: "{{ get "libvirt.pool" }}"
@@ -107,6 +115,8 @@ pull = "{{ get "container.pull" }}"
 
 // initConfig reads in config file and ENV variables if set.
 func initConfig() {
+	viper.SetDefault("libvirt.socket", "/var/run/libvirt/libvirt-sock")
+	viper.SetDefault("libvirt.uri", "qemu:///system")
 	viper.SetDefault("libvirt.pool", "default")
 	viper.SetDefault("libvirt.network", "default")
 	viper.SetDefault("libvirt.static_dhcp", false)

cmd/virter.go

@@ -2,10 +2,10 @@ package cmd
 
 import (
 	"fmt"
-	"net"
 	"time"
 
 	"github.com/digitalocean/go-libvirt"
+	"github.com/digitalocean/go-libvirt/socket/dialers"
 	"github.com/spf13/viper"
 
 	"github.com/LINBIT/virter/internal/virter"
@@ -14,13 +14,11 @@ import (
 
 // InitVirter initializes virter by connecting to the local libvirt instance and configures the ssh keystore.
 func InitVirter() (*virter.Virter, error) {
-	c, err := net.DialTimeout("unix", "/var/run/libvirt/libvirt-sock", 2*time.Second)
-	if err != nil {
-		return nil, fmt.Errorf("failed to dial libvirt: %w", err)
-	}
-
-	l := libvirt.New(c)
-	if err := l.Connect(); err != nil {
+	l := libvirt.NewWithDialer(dialers.NewLocal(
+		dialers.WithSocket(viper.GetString("libvirt.socket")),
+		dialers.WithLocalTimeout(2*time.Second),
+	))
+	if err := l.ConnectToURI(libvirt.ConnectURI(viper.GetString("libvirt.uri"))); err != nil {
 		return nil, fmt.Errorf("failed to connect to libvirt socket: %w", err)
 	}