feat(run)!: Disable QEMU preamble and add option to show it (#656)

Approved-by: Alexander Jung <[email protected]>

machine/qemu/init.go

@@ -4,7 +4,13 @@
 // You may not use this file except in compliance with the License.
 package qemu
 
-import "encoding/gob"
+import (
+	"encoding/gob"
+
+	"kraftkit.sh/cmdfactory"
+)
+
+var qemuShowSgaBiosPreamble bool
 
 func init() {
 	// Register only used supported interfaces later used for serialization.  To
@@ -468,4 +474,15 @@ func init() {
 
 	// CLI configuration
 	gob.Register(QemuConfig{})
+
+	// Register additional command-line arguments
+	cmdfactory.RegisterFlag(
+		"kraft run",
+		cmdfactory.BoolVar(
+			&qemuShowSgaBiosPreamble,
+			"qemu-sgabios-preamble",
+			false,
+			"Show the QEMU SGABIOS preamble when running a unikernel",
+		),
+	)
 }

machine/qemu/v1alpha1.go

@@ -685,7 +685,30 @@ func (service *machineV1alpha1Service) Pause(ctx context.Context, machine *machi
 
 // Logs implements kraftkit.sh/api/machine/v1alpha1.MachineService
 func (service *machineV1alpha1Service) Logs(ctx context.Context, machine *machinev1alpha1.Machine) (chan string, chan error, error) {
-	return logtail.NewLogTail(ctx, machine.Status.LogFile)
+	out, errOut, err := logtail.NewLogTail(ctx, machine.Status.LogFile)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Wait and trim the preamble from the logs before returning
+	for {
+		select {
+		case line := <-out:
+			if !qemuShowSgaBiosPreamble {
+				if strings.Contains(line, "Booting from ") {
+					qemuShowSgaBiosPreamble = true
+				}
+				continue
+			}
+			return out, errOut, nil
+
+		case err := <-errOut:
+			return nil, nil, err
+
+		case <-ctx.Done():
+			return out, errOut, nil
+		}
+	}
 }
 
 // Get implements kraftkit.sh/api/machine/v1alpha1/MachineService.Get