setup: Don't mount devtmpfs if not needed

If we're running in a virtual machine, there is no need to mount /dev
in the container (it will be mounted in the vm). This is important
because in a rootless container we're not allowed to mount devtmpfs.

Author: alexlarsson

cmd/image-builder/bib_main.go

@@ -290,7 +290,7 @@ func bibCmdBuild(cmd *cobra.Command, args []string) error {
 	case false:
 		fmt.Fprintf(os.Stderr, "WARNING: running outside a container, this is an unsupported configuration\n")
 	case true:
-		if err := setup.EnsureEnvironment(osbuildStore); err != nil {
+		if err := setup.EnsureEnvironment(osbuildStore, false); err != nil {
 			return fmt.Errorf("cannot ensure the environment: %w", err)
 		}
 	}

cmd/image-builder/main.go

@@ -390,7 +390,7 @@ func cmdBuild(cmd *cobra.Command, args []string) error {
 
 	// Setup osbuild environment if running in a container
 	if setup.IsContainer() {
-		if err := setup.EnsureEnvironment(cacheDir); err != nil {
+		if err := setup.EnsureEnvironment(cacheDir, false); err != nil {
 			return fmt.Errorf("entrypoint setup failed: %w", err)
 		}
 	}

pkg/setup/setup.go

@@ -17,7 +17,7 @@ import (
 
 // EnsureEnvironment mutates external filesystem state as necessary
 // to run in a container environment.  This function is idempotent.
-func EnsureEnvironment(storePath string) error {
+func EnsureEnvironment(storePath string, inVm bool) error {
 	osbuildPath := "/usr/bin/osbuild"
 	if util.IsMountpoint(osbuildPath) {
 		return nil
@@ -63,9 +63,11 @@ func EnsureEnvironment(storePath string) error {
 	}
 
 	// Ensure we have devfs inside the container to get dynamic loop
-	// loop devices inside the container.
-	if err := util.RunCmdSync("mount", "-t", "devtmpfs", "devtmpfs", "/dev"); err != nil {
-		return err
+	// loop devices inside the container. (Not needed if in a vm)
+	if !inVm {
+		if err := util.RunCmdSync("mount", "-t", "devtmpfs", "devtmpfs", "/dev"); err != nil {
+			return err
+		}
 	}
 
 	// Create a bind mount into our target location; we can't copy it because