util: distro: Refactor family and distro code

I hate writing abstraction code like this, but I'm hoping it will be
useful.

examples/lang/family.mcl

@@ -2,8 +2,8 @@ import "fmt"
 import "os"
 
 print "debian" {
-	msg => fmt.printf("is_debian: %t", os.is_debian()),
+	msg => fmt.printf("is_family_debian: %t", os.is_family_debian()),
 }
 print "redhat" {
-	msg => fmt.printf("is_redhat: %t", os.is_redhat()),
+	msg => fmt.printf("is_family_redhat: %t", os.is_family_redhat()),
 }

examples/lang/pkg1.mcl

@@ -2,5 +2,5 @@ import "os"
 
 pkg "cowsay" {
 	state => "installed",
-	allowunsupported => os.is_debian() ?: true,
+	allowunsupported => os.is_family_debian() ?: true,
 }

lang/core/os/family_func.go

@@ -31,11 +31,11 @@ package coreos
 
 import (
 	"context"
-	"os"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
 	"github.com/purpleidea/mgmt/lang/funcs/vars"
 	"github.com/purpleidea/mgmt/lang/types"
+	distroUtil "github.com/purpleidea/mgmt/util/distro"
 )
 
 func init() {
@@ -46,129 +46,70 @@ func init() {
 
 	vars.ModuleRegister(ModuleName, "family_redhat", func() vars.Value {
 		return &types.StrValue{
-			V: familyRedHat,
+			V: distroUtil.FamilyRedHat,
 		}
 	})
 	vars.ModuleRegister(ModuleName, "family_debian", func() vars.Value {
 		return &types.StrValue{
-			V: familyDebian,
+			V: distroUtil.FamilyDebian,
 		}
 	})
 	vars.ModuleRegister(ModuleName, "family_archlinux", func() vars.Value {
 		return &types.StrValue{
-			V: familyArchLinux,
+			V: distroUtil.FamilyArchLinux,
 		}
 	})
 
 	// TODO: Create a family method that will return a giant struct.
-	simple.ModuleRegister(ModuleName, "is_redhat", &simple.Scaffold{
+	simple.ModuleRegister(ModuleName, "is_family_redhat", &simple.Scaffold{
 		T: types.NewType("func() bool"),
-		F: IsRedHat,
+		F: IsFamilyRedHat,
 	})
-	simple.ModuleRegister(ModuleName, "is_debian", &simple.Scaffold{
+	simple.ModuleRegister(ModuleName, "is_family_debian", &simple.Scaffold{
 		T: types.NewType("func() bool"),
-		F: IsDebian,
+		F: IsFamilyDebian,
 	})
-	simple.ModuleRegister(ModuleName, "is_archlinux", &simple.Scaffold{
+	simple.ModuleRegister(ModuleName, "is_family_archlinux", &simple.Scaffold{
 		T: types.NewType("func() bool"),
-		F: IsArchLinux,
+		F: IsFamilyArchLinux,
 	})
 }
 
-const (
-	familyRedHat    = "redhat"
-	familyDebian    = "debian"
-	familyArchLinux = "archlinux"
-)
-
 // Family returns the distro family.
 // TODO: Detect OS changes.
 func Family(ctx context.Context, input []types.Value) (types.Value, error) {
-	if b, err := isRedHat(ctx); err != nil {
+	s, err := distroUtil.Family(ctx)
+	if err != nil {
 		return nil, err
-	} else if b {
-		return &types.StrValue{
-			V: familyRedHat,
-		}, nil
-	}
-	if b, err := isDebian(ctx); err != nil {
-		return nil, err
-	} else if b {
-		return &types.StrValue{
-			V: familyDebian,
-		}, nil
-	}
-	if b, err := isArchLinux(ctx); err != nil {
-		return nil, err
-	} else if b {
-		return &types.StrValue{
-			V: familyArchLinux,
-		}, nil
 	}
 	return &types.StrValue{
-		V: "", // unknown
+		V: s, // empty if unknown
 	}, nil
 }
 
-// IsRedHat detects if the os family is redhat.
+// IsFamilyRedHat detects if the os family is redhat.
 // TODO: Detect OS changes.
-func IsRedHat(ctx context.Context, input []types.Value) (types.Value, error) {
-	b, err := isRedHat(ctx)
+func IsFamilyRedHat(ctx context.Context, input []types.Value) (types.Value, error) {
+	b, err := distroUtil.IsFamilyRedHat(ctx)
 	return &types.BoolValue{
 		V: b,
 	}, err
 }
 
-// IsDebian detects if the os family is debian.
+// IsFamilyDebian detects if the os family is debian.
 // TODO: Detect OS changes.
-func IsDebian(ctx context.Context, input []types.Value) (types.Value, error) {
-	b, err := isDebian(ctx)
+func IsFamilyDebian(ctx context.Context, input []types.Value) (types.Value, error) {
+	b, err := distroUtil.IsFamilyDebian(ctx)
 	return &types.BoolValue{
 		V: b,
 	}, err
 }
 
-// IsArchLinux detects if the os family is archlinux.
+// IsFamilyArchLinux detects if the os family is archlinux.
 // TODO: Detect OS changes.
-func IsArchLinux(ctx context.Context, input []types.Value) (types.Value, error) {
-	b, err := isArchLinux(ctx)
+func IsFamilyArchLinux(ctx context.Context, input []types.Value) (types.Value, error) {
+	b, err := distroUtil.IsFamilyArchLinux(ctx)
 	return &types.BoolValue{
 		V: b,
 	}, err
 }
-
-func isRedHat(ctx context.Context) (bool, error) {
-	// TODO: use ctx around io operations
-	_, err := os.Stat("/etc/redhat-release")
-	if os.IsNotExist(err) {
-		return false, nil
-	}
-	if err != nil {
-		return false, err
-	}
-	return true, nil
-}
-
-func isDebian(ctx context.Context) (bool, error) {
-	// TODO: use ctx around io operations
-	_, err := os.Stat("/etc/debian_version")
-	if os.IsNotExist(err) {
-		return false, nil
-	}
-	if err != nil {
-		return false, err
-	}
-	return true, nil
-}
-
-func isArchLinux(ctx context.Context) (bool, error) {
-	// TODO: use ctx around io operations
-	_, err := os.Stat("/etc/arch-release")
-	if os.IsNotExist(err) {
-		return false, nil
-	}
-	if err != nil {
-		return false, err
-	}
-	return true, nil
-}

lang/interpret_test/TestAstFunc1/importscope0.txtar

@@ -9,7 +9,7 @@ import "fmt"
 class xclass {
 	#import "os" # this should not be required, top-level should be enough
 
-	$aaa = if os.is_debian() { "bbb" }  else { "ccc" }
+	$aaa = if os.is_family_debian() { "bbb" }  else { "ccc" }
 
 	print "${aaa}" {
 		msg => "hello",

lang/interpret_test/TestAstFunc1/importscope1.txtar

@@ -9,11 +9,11 @@ import "fmt"
 
 class xclass {
 	# note that `os` is not imported here
-	$aaa = if os.is_debian() { "bbb" }  else { "ccc" }
+	$aaa = if os.is_family_debian() { "bbb" }  else { "ccc" }
 
 	print "${aaa}" {
 		msg => "hello",
 	}
 }
 -- OUTPUT --
-# err: errSetScope: func `os.is_debian` does not exist in this scope
+# err: errSetScope: func `os.is_family_debian` does not exist in this scope

lang/interpret_test/TestAstFunc1/importscope2.txtar

@@ -8,7 +8,7 @@ import "fmt"
 class xclass {
 	import "os" # we can also use a scoped local import
 
-	$aaa = if os.is_debian() { "bbb" }  else { "ccc" }
+	$aaa = if os.is_family_debian() { "bbb" }  else { "ccc" }
 
 	print "${aaa}" {
 		msg => "hello",

modules/purpleidea/main.mcl

@@ -31,7 +31,7 @@ import "os"
 
 # base contains the personal tweaks and utilities of james (purpleidea)
 class base() {
-	if os.is_redhat() {
+	if os.is_family_redhat() {
 		pkg [
 			"ack",
 			"bash-completion",
@@ -53,7 +53,7 @@ class base() {
 			state => "installed",
 		}
 	}
-	if os.is_debian() {
+	if os.is_family_debian() {
 		pkg [
 			"ack",
 			"bash-completion",

util/distro/distro.go

@@ -31,17 +31,39 @@
 // these all in one place so that adding this data happens all in the same file.
 package distro
 
+import (
+	"context"
+	"os"
+)
+
+const (
+	// FamilyRedHat represents distros like Fedora and RHEL.
+	FamilyRedHat = "redhat"
+
+	// FamilyDebian represents distros like Debian and Ubuntu.
+	FamilyDebian = "debian"
+
+	// FamilyArchLinux represents primarily ArchLinux.
+	FamilyArchLinux = "archlinux"
+
+	// DistroDebian is the Debian distro.
+	DistroDebian = "debian"
+
+	// DistroFedora is the Fedora distro.
+	DistroFedora = "fedora"
+)
+
 var (
 	// MapDistroToBootstrapPackages is a map of distro to packages needed to
 	// run our software.
 	MapDistroToBootstrapPackages = map[string][]string{
 		// TODO: add more values
-		"debian": {
+		DistroDebian: {
 			"libaugeas-dev",
 			"libvirt-dev",
 			"packagekit-tools",
 		},
-		"fedora": {
+		DistroFedora: {
 			"augeas-devel",
 			"libvirt-devel",
 			"PackageKit",
@@ -55,3 +77,62 @@ func DistroToBootstrapPackages(distro string) ([]string, bool) {
 	l, exists := MapDistroToBootstrapPackages[distro]
 	return l, exists
 }
+
+// Family returns the distro family.
+func Family(ctx context.Context) (string, error) {
+	if b, err := IsFamilyRedHat(ctx); err != nil {
+		return "", err
+	} else if b {
+		return FamilyRedHat, nil
+	}
+	if b, err := IsFamilyDebian(ctx); err != nil {
+		return "", err
+	} else if b {
+		return FamilyDebian, nil
+	}
+	if b, err := IsFamilyArchLinux(ctx); err != nil {
+		return "", err
+	} else if b {
+		return FamilyArchLinux, nil
+	}
+	return "", nil // unknown
+}
+
+// IsFamilyRedHat detects if the os family is redhat.
+func IsFamilyRedHat(ctx context.Context) (bool, error) {
+	// TODO: use ctx around io operations
+	_, err := os.Stat("/etc/redhat-release")
+	if os.IsNotExist(err) {
+		return false, nil
+	}
+	if err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+// IsFamilyDebian detects if the os family is debian.
+func IsFamilyDebian(ctx context.Context) (bool, error) {
+	// TODO: use ctx around io operations
+	_, err := os.Stat("/etc/debian_version")
+	if os.IsNotExist(err) {
+		return false, nil
+	}
+	if err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+// IsFamilyArchLinux detects if the os family is archlinux.
+func IsFamilyArchLinux(ctx context.Context) (bool, error) {
+	// TODO: use ctx around io operations
+	_, err := os.Stat("/etc/arch-release")
+	if os.IsNotExist(err) {
+		return false, nil
+	}
+	if err != nil {
+		return false, err
+	}
+	return true, nil
+}