Add initial translation support.

pkg/util/i18n/BUILD

@@ -0,0 +1,28 @@
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+    "go_test",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["i18n.go"],
+    tags = ["automanaged"],
+    deps = [
+        "//pkg/generated:go_default_library",
+        "//vendor:github.com/chai2010/gettext-go/gettext",
+        "//vendor:github.com/golang/glog",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["i18n_test.go"],
+    library = "go_default_library",
+    tags = ["automanaged"],
+    deps = [],
+)

pkg/util/i18n/i18n.go

@@ -0,0 +1,133 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package i18n
+
+import (
+	"archive/zip"
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+
+	"k8s.io/kubernetes/pkg/generated"
+
+	"github.com/chai2010/gettext-go/gettext"
+	"github.com/golang/glog"
+)
+
+var knownTranslations = map[string][]string{
+	"kubectl": {
+		"default",
+		"en_US",
+	},
+	// only used for unit tests.
+	"test": {
+		"default",
+		"en_US",
+	},
+}
+
+func loadSystemLanguage() string {
+	langStr := os.Getenv("LANG")
+	if langStr == "" {
+		glog.V(3).Infof("Couldn't find the LANG environment variable, defaulting to en-US")
+		return "default"
+	}
+	pieces := strings.Split(langStr, ".")
+	if len(pieces) == 0 {
+		glog.V(3).Infof("Unexpected system language (%s), defaulting to en-US", langStr)
+		return "default"
+	}
+	return pieces[0]
+}
+
+func findLanguage(root string, getLanguageFn func() string) string {
+	langStr := getLanguageFn()
+
+	translations := knownTranslations[root]
+	if translations != nil {
+		for ix := range translations {
+			if translations[ix] == langStr {
+				return langStr
+			}
+		}
+	}
+	glog.V(3).Infof("Couldn't find translations for %s, using default", langStr)
+	return "default"
+}
+
+// LoadTranslations loads translation files. getLanguageFn should return a language
+// string (e.g. 'en-US'). If getLanguageFn is nil, then the loadSystemLanguage function
+// is used, which uses the 'LANG' environment variable.
+func LoadTranslations(root string, getLanguageFn func() string) error {
+	if getLanguageFn == nil {
+		getLanguageFn = loadSystemLanguage
+	}
+
+	langStr := findLanguage(root, getLanguageFn)
+	translationFiles := []string{
+		fmt.Sprintf("%s/%s/LC_MESSAGES/k8s.po", root, langStr),
+		fmt.Sprintf("%s/%s/LC_MESSAGES/k8s.mo", root, langStr),
+	}
+
+	glog.V(3).Infof("Setting language to %s", langStr)
+	// TODO: list the directory and load all files.
+	buf := new(bytes.Buffer)
+	w := zip.NewWriter(buf)
+
+	// Make sure to check the error on Close.
+	for _, file := range translationFiles {
+		filename := "translations/" + file
+		f, err := w.Create(file)
+		if err != nil {
+			return err
+		}
+		data, err := generated.Asset(filename)
+		if err != nil {
+			return err
+		}
+		if _, err := f.Write(data); err != nil {
+			return nil
+		}
+	}
+	if err := w.Close(); err != nil {
+		return err
+	}
+	gettext.BindTextdomain("k8s", root+".zip", buf.Bytes())
+	gettext.Textdomain("k8s")
+	gettext.SetLocale(langStr)
+	return nil
+}
+
+// T translates a string, possibly substituting arguments into it along
+// the way. If len(args) is > 0, args1 is assumed to be the plural value
+// and plural translation is used.
+func T(defaultValue string, args ...int) string {
+	if len(args) == 0 {
+		return gettext.PGettext(defaultValue, defaultValue)
+	}
+	return fmt.Sprintf(gettext.PNGettext(defaultValue, defaultValue, defaultValue+".plural", args[0]),
+		args[0])
+}
+
+// Errorf produces an error with a translated error string.
+// Substitution is performed via the `T` function above, following
+// the same rules.
+func Errorf(defaultValue string, args ...int) error {
+	return errors.New(T(defaultValue, args...))
+}

pkg/util/i18n/i18n_test.go

@@ -0,0 +1,64 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package i18n
+
+import (
+	"os"
+	"testing"
+)
+
+func TestTranslation(t *testing.T) {
+	err := LoadTranslations("test", func() string { return "default" })
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	result := T("test_string")
+	if result != "foo" {
+		t.Errorf("expected: %s, saw: %s", "foo", result)
+	}
+}
+
+func TestTranslationPlural(t *testing.T) {
+	err := LoadTranslations("test", func() string { return "default" })
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	result := T("test_plural", 3)
+	if result != "there were 3 items" {
+		t.Errorf("expected: %s, saw: %s", "there were 3 items", result)
+	}
+
+	result = T("test_plural", 1)
+	if result != "there was 1 item" {
+		t.Errorf("expected: %s, saw: %s", "there was 1 item", result)
+	}
+}
+
+func TestTranslationEnUSEnv(t *testing.T) {
+	os.Setenv("LANG", "en_US.UTF-8")
+	err := LoadTranslations("test", nil)
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	result := T("test_string")
+	if result != "baz" {
+		t.Errorf("expected: %s, saw: %s", "baz", result)
+	}
+}