daemon: allow an extension to install group of packages

In the previous implementation, an extension was one to one
mapping with the package it would install on the host. This can
become confusing if enabling an extension would require
installing multiple sets of packages which are not install
time dependency.

Also added e2e test for kernel-devel extensions

pkg/daemon/update.go

@@ -865,22 +865,43 @@ func generateExtensionsArgs(oldConfig, newConfig *mcfgv1.MachineConfig) []string
 		}
 	}
 
+	// Supported extensions has package list info that is required
+	// to enable an extension
+	extensions := getSupportedExtensions()
+
 	extArgs := []string{"update"}
 	for _, ext := range added {
-		extArgs = append(extArgs, "--install", ext)
+		for _, pkg := range extensions[ext] {
+			extArgs = append(extArgs, "--install", pkg)
+		}
 	}
 	for _, ext := range removed {
-		extArgs = append(extArgs, "--uninstall", ext)
+		for _, pkg := range extensions[ext] {
+			extArgs = append(extArgs, "--uninstall", pkg)
+		}
 	}
 
 	return extArgs
 }
 
+// Returns list of extensions possible to install on a CoreOS based system.
+func getSupportedExtensions() map[string][]string {
+	// In future when list of extensions grow, it will make
+	// more sense to populate it in a dynamic way.
+
+	// These are RHCOS supported extensions.
+	// Each extension keeps a list of packages required to get enabled on host.
+	return map[string][]string{
+		"usbguard":     {"usbguard"},
+		"kernel-devel": {"kernel-devel", "kernel-headers"},
+	}
+}
+
 func validateExtensions(exts []string) error {
-	supportedExtensions := []string{"usbguard", "kernel-devel"}
+	supportedExtensions := getSupportedExtensions()
 	invalidExts := []string{}
 	for _, ext := range exts {
-		if !ctrlcommon.InSlice(ext, supportedExtensions) {
+		if _, ok := supportedExtensions[ext]; !ok {
 			invalidExts = append(invalidExts, ext)
 		}
 	}

test/e2e/mcd_test.go

@@ -252,7 +252,7 @@ func TestExtensions(t *testing.T) {
 			Config: runtime.RawExtension{
 				Raw: helpers.MarshalOrDie(ctrlcommon.NewIgnConfig()),
 			},
-			Extensions: []string{"usbguard"},
+			Extensions: []string{"usbguard", "kernel-devel"},
 		},
 	}
 
@@ -269,10 +269,14 @@ func TestExtensions(t *testing.T) {
 	assert.Equal(t, infraNode.Annotations[constants.CurrentMachineConfigAnnotationKey], renderedConfig)
 	assert.Equal(t, infraNode.Annotations[constants.MachineConfigDaemonStateAnnotationKey], constants.MachineConfigDaemonStateDone)
 
-	installedExtesnions := execCmdOnNode(t, cs, infraNode, "chroot", "/rootfs", "rpm", "-qa", "usbguard")
-	if !strings.Contains(installedExtesnions, "usbguard") {
-		t.Fatalf("Node %s doesn't have expected extensions", infraNode.Name)
+	installedPackages := execCmdOnNode(t, cs, infraNode, "chroot", "/rootfs", "rpm", "-q", "usbguard", "kernel-devel", "kernel-headers")
+	expectedPackages := []string{"usbguard", "kernel-devel", "kernel-headers"}
+	for _, v := range expectedPackages {
+		if !strings.Contains(installedPackages, v) {
+			t.Fatalf("Node %s doesn't have expected extensions", infraNode.Name)
+		}
 	}
+
 	t.Logf("Node %s has expected extensions installed", infraNode.Name)
 
 	// Delete the applied kerneltype MachineConfig to make sure rollback works fine
@@ -292,10 +296,15 @@ func TestExtensions(t *testing.T) {
 
 	assert.Equal(t, infraNode.Annotations[constants.CurrentMachineConfigAnnotationKey], oldInfraRenderedConfig)
 	assert.Equal(t, infraNode.Annotations[constants.MachineConfigDaemonStateAnnotationKey], constants.MachineConfigDaemonStateDone)
-	installedExtesnions = execCmdOnNode(t, cs, infraNode, "chroot", "/rootfs", "rpm", "-qa", "usbguard")
-	if strings.Contains(installedExtesnions, "usbguard") {
-		t.Fatalf("Node %s did not rollback successfully", infraNode.Name)
+
+	installedPackages = execCmdOnNode(t, cs, infraNode, "chroot", "/rootfs", "rpm", "-qa", "usbguard", "kernel-devel", "kernel-headers")
+	expectedPackages = []string{"usbguard", "kernel-devel", "kernel-headers"}
+	for _, v := range expectedPackages {
+		if strings.Contains(installedPackages, v) {
+			t.Fatalf("Node %s did not rollback successfully", infraNode.Name)
+		}
 	}
+
 	t.Logf("Node %s has successfully rolled back", infraNode.Name)
 
 	unlabelFunc()