util: distro, engine: resources: Update virt-builder res

A little easier to maintain if we support more distros eventually.

engine/resources/virt_builder.go

@@ -199,19 +199,20 @@ func (obj *VirtBuilderRes) getBinaryPath() (string, error) {
 
 // getGuestfs returns the package to install for our os so that we can run
 // virt-builder.
-func (obj *VirtBuilderRes) getGuestfs() (string, error) {
+func (obj *VirtBuilderRes) getGuestfs() ([]string, error) {
 	// TODO: Improve this function as things evolve.
-
-	if _, err := os.Stat("/etc/redhat-release"); err == nil { // fedora
-		return "guestfs-tools", nil
+	distro, err := distroUtil.Distro(context.TODO()) // what is this resource running in?
+	if err != nil {
+		return nil, nil
 	}
 
-	if _, err := os.Stat("/etc/debian_version"); err == nil { // debian
-		return "guestfs-tools", nil
+	packages, exists := distroUtil.DistroToGuestfsPackages(distro)
+	if !exists {
+		// TODO: patches welcome!
+		return nil, fmt.Errorf("os/version is not supported")
 	}
 
-	// TODO: patches welcome!
-	return "", fmt.Errorf("os/version is not supported")
+	return packages, nil
 }
 
 // getDeps returns a list of packages to install for the specific os-version so
@@ -307,7 +308,7 @@ func (obj *VirtBuilderRes) Init(init *engine.Init) error {
 		return nil
 	}
 
-	// Try to get the package of the binary...
+	// Try to get the packages for the binary...
 	p, err := obj.getGuestfs()
 	if err != nil {
 		return err
@@ -317,9 +318,11 @@ func (obj *VirtBuilderRes) Init(init *engine.Init) error {
 	defer virtBuilderMutex.Unlock()
 
 	// Try to install the binary...
-	obj.init.Logf("installing: %s", p)
-	if err := InstallOnePackage(context.TODO(), p); err != nil {
-		return err
+	for _, x := range p {
+		obj.init.Logf("installing: %s", x)
+		if err := InstallOnePackage(context.TODO(), x); err != nil {
+			return err
+		}
 	}
 
 	return nil

util/distro/distro.go

@@ -71,6 +71,18 @@ var (
 			"PackageKit",
 		},
 	}
+
+	// MapDistroToGuestfsPackages is a map of distro to packages needed to
+	// run the virt-builder software and guestfs suite.
+	MapDistroToGuestfsPackages = map[string][]string{
+		// TODO: add more values
+		DistroDebian: {
+			"guestfs-tools",
+		},
+		DistroFedora: {
+			"guestfs-tools",
+		},
+	}
 )
 
 // DistroToBootstrapPackages returns the list of packages corresponding to the
@@ -80,6 +92,14 @@ func DistroToBootstrapPackages(distro string) ([]string, bool) {
 	return l, exists
 }
 
+// DistroToGuestfsPackages returns the list of packages corresponding to the
+// distro for running the virt-builder software and guestfs suite. This returns
+// false if the value doesn't exist.
+func DistroToGuestfsPackages(distro string) ([]string, bool) {
+	l, exists := MapDistroToGuestfsPackages[distro]
+	return l, exists
+}
+
 // Family returns the distro family.
 func Family(ctx context.Context) (string, error) {
 	if b, err := IsFamilyRedHat(ctx); err != nil {