OSModifier: Add kernel cmdline in EMU API and update extraCommandLine…

… to a list (#23)

<!-- Description: Please provide a summary of the changes and the
motivation behind them. -->

cherry-picked from
#19 with
commits signed and comments addressed.


What does the PR accomplish, why was it needed?

Now extraCommandLine format is consistent with trident API (see related
PR in trident:
https://dev.azure.com/mariner-org/ECF/_git/trident/pullrequest/20937).
It also avoids complexity with string parsing.

- update extraCommandLine to a list of strings
- Add kernel cmdline in EMU API

---

### **Checklist**
- [x] Tests added/updated
- [x] Documentation updated (if needed)
- [x] Code conforms to style guidelines

toolkit/tools/imagecustomizer/docs/configuration.md

@@ -780,7 +780,7 @@ Optional settings for where and how to mount the filesystem.
 
 Options for configuring the kernel.
 
-### extraCommandLine [string]
+### extraCommandLine [string[]]
 
 Additional Linux kernel command line options to add to the image.
 

toolkit/tools/imagecustomizer/docs/iso.md

@@ -90,7 +90,8 @@ iso:
     cloud-init-data/meta-data: /cloud-init-data/meta-data
 
   kernelCommandLine:
-    extraCommandLine: "ds=nocloud"
+    extraCommandLine:
+    - "ds=nocloud"
 ```
 
 Note: It is tempting to specify
@@ -106,7 +107,8 @@ If cloud-init data is to be placed within the LiveOS root file system:
 ```yaml
 os:
   kernelCommandLine:
-    extraCommandLine: "ds=nocloud"
+    extraCommandLine:
+    - "ds=nocloud"
 
   additionalFiles:
     cloud-init-data/user-data: /var/lib/cloud/seed/nocloud/user-data

toolkit/tools/imagecustomizerapi/config_test.go

@@ -336,8 +336,11 @@ func TestConfigIsValidKernelCLI(t *testing.T) {
 		OS: &OS{
 			ResetBootLoaderType: "hard-reset",
 			Hostname:            "test",
+
 			KernelCommandLine: KernelCommandLine{
-				ExtraCommandLine: "console=ttyS0",
+				ExtraCommandLine: []string{
+					"console=ttyS0",
+				},
 			},
 		},
 	}

toolkit/tools/imagecustomizerapi/iso_test.go

@@ -12,7 +12,7 @@ import (
 func TestIsoIsValid(t *testing.T) {
 	iso := Iso{
 		KernelCommandLine: KernelCommandLine{
-			ExtraCommandLine: "'",
+			ExtraCommandLine: []string{""},
 		},
 	}
 

toolkit/tools/imagecustomizerapi/kernelcommandline.go

@@ -3,16 +3,20 @@
 
 package imagecustomizerapi
 
+import (
+	"fmt"
+)
+
 type KernelCommandLine struct {
 	// Extra kernel command line args.
-	ExtraCommandLine KernelExtraArguments `yaml:"extraCommandLine"`
+	ExtraCommandLine []string `yaml:"extraCommandLine"`
 }
 
-func (s *KernelCommandLine) IsValid() error {
-	err := s.ExtraCommandLine.IsValid()
-	if err != nil {
-		return err
+func (k *KernelCommandLine) IsValid() error {
+	for i, arg := range k.ExtraCommandLine {
+		if arg == "" {
+			return fmt.Errorf("kernel argument cannot be empty at index %d", i)
+		}
 	}
-
 	return nil
 }

toolkit/tools/imagecustomizerapi/os_test.go

@@ -219,7 +219,7 @@ func TestOSIsValidOverlayDuplicateWorkDir(t *testing.T) {
 func TestOSIsValidInvalidKernelCommandLine(t *testing.T) {
 	os := OS{
 		KernelCommandLine: KernelCommandLine{
-			ExtraCommandLine: "\"",
+			ExtraCommandLine: []string{""},
 		},
 	}
 

toolkit/tools/osmodifierapi/os.go

@@ -13,10 +13,11 @@ import (
 
 // OS defines how each system present on the image is supposed to be configured.
 type OS struct {
-	Hostname string                     `yaml:"hostname"`
-	SELinux  imagecustomizerapi.SELinux `yaml:"selinux"`
-	Users    []imagecustomizerapi.User  `yaml:"users"`
-	Overlays *[]Overlay                 `yaml:"overlays"`
+	Hostname          string                               `yaml:"hostname"`
+	SELinux           imagecustomizerapi.SELinux           `yaml:"selinux"`
+	Users             []imagecustomizerapi.User            `yaml:"users"`
+	Overlays          *[]Overlay                           `yaml:"overlays"`
+	KernelCommandLine imagecustomizerapi.KernelCommandLine `yaml:"kernelCommandLine"`
 }
 
 func (s *OS) IsValid() error {
@@ -65,5 +66,10 @@ func (s *OS) IsValid() error {
 		}
 	}
 
+	err = s.KernelCommandLine.IsValid()
+	if err != nil {
+		return fmt.Errorf("invalid kernelCommandLine:\n%w", err)
+	}
+
 	return nil
 }