Add goauth binary for GOAUTH environment support

cmd/goauth/main.go

@@ -0,0 +1,103 @@
+// Copyright 2022 Google LLC All Rights Reserved.
+//
+// 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 main
+
+import (
+	"context"
+	"encoding/base64"
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/GoogleCloudPlatform/artifact-registry-go-tools/pkg/auth"
+)
+
+const help = `
+Handle Go authentication with Google Cloud Artifact Registry Go Repositories.
+
+Add to your GOAUTH environment variable:
+
+  export GOAUTH="sh -c 'GOPROXY=direct go run github.com/GoogleCloudPlatform/artifact-registry-go-tools/cmd/goauth@latest <location>'"
+
+To support multiple locations, add the command multiple times to the GOAUTH variable (semicolon-separated).
+
+For more details, see https://pkg.go.dev/cmd/go@master#hdr-GOAUTH_environment_variable`
+
+const defaultHostPattern = "%s-go.pkg.dev"
+
+func main() {
+	jsonKey := flag.String("json_key", "", "path to the json key of the service account used for this location. Leave empty to use the oauth token instead.")
+	hostPattern := flag.String("host_pattern", defaultHostPattern, "Artifact Registry server host pattern, where %s will be replaced by a location string.")
+
+	flag.Parse()
+
+	location := flag.Arg(0)
+	if location == "" {
+		fmt.Fprintln(os.Stderr, help)
+		return
+	}
+	if strings.HasPrefix(location, "https://") {
+		log.Println("Location has to be a Google Cloud region, e.g. 'us-central1'.")
+		os.Exit(2)
+	}
+
+	// generate the authentication header
+	urlLine := locationURL(location, *hostPattern)
+	authHeader, err := keyAuthHeader(*jsonKey)
+	if err != nil {
+		log.Println(err)
+		os.Exit(3)
+	}
+
+	// send the Go authentication information
+	fmt.Printf("%s\n\nAuthorization: %s\n\n", urlLine, authHeader)
+}
+
+func locationURL(location string, hostPattern string) string {
+	host := fmt.Sprintf(hostPattern, location)
+
+	return fmt.Sprintf("https://%s", host)
+}
+
+func keyAuthHeader(jsonKeyPath string) (string, error) {
+	ctx := context.Background()
+	ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
+	defer cancel()
+
+	if jsonKeyPath != "" {
+		key, err := auth.EncodeJsonKey(jsonKeyPath)
+		if err != nil {
+			return "", fmt.Errorf("failed to encode JSON key: %w", err)
+		}
+
+		return basicAuthHeader("_json_key_base64", key), nil
+	} else {
+		token, err := auth.Token(ctx)
+		if err != nil {
+			return "", fmt.Errorf("failed to get oauth token: %w", err)
+		}
+
+		return basicAuthHeader("oauth2accesstoken", token), nil
+	}
+}
+
+func basicAuthHeader(username, password string) string {
+	a := fmt.Sprintf("%s:%s", username, password)
+	b := base64.StdEncoding.EncodeToString([]byte(a))
+
+	return fmt.Sprintf("Basic %s", b)
+}

cmd/goauth/main_test.go

@@ -0,0 +1,63 @@
+package main
+
+import (
+	"encoding/base64"
+	"strings"
+	"testing"
+)
+
+func TestLocationURL(t *testing.T) {
+	url := locationURL("us-central1", defaultHostPattern)
+
+	if url != "https://us-central1-go.pkg.dev" {
+		t.Fatalf("unexpected url: %s", url)
+	}
+}
+
+func TestAuthHeader_DefaultCredentials(t *testing.T) {
+	header, err := keyAuthHeader("")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	t.Logf("header: %s", header)
+
+	if !strings.HasPrefix(header, "Basic ") {
+		t.Fatal(err)
+	}
+
+	decoded, err := base64.StdEncoding.DecodeString(header[6:])
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	t.Logf("decoded: %s", decoded)
+
+	if !strings.HasPrefix(string(decoded), "oauth2accesstoken:") {
+		t.Fatal(err)
+	}
+}
+
+func TestAuthHeader_JSONKey(t *testing.T) {
+	header, err := keyAuthHeader("./test/dummy.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	t.Logf("header: %s", header)
+
+	if !strings.HasPrefix(header, "Basic ") {
+		t.Fatal(err)
+	}
+
+	decoded, err := base64.StdEncoding.DecodeString(header[6:])
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	t.Logf("decoded: %s", decoded)
+
+	if !strings.HasPrefix(string(decoded), "_json_key_base64:") {
+		t.Fatal(err)
+	}
+}

cmd/goauth/test/dummy.json

@@ -0,0 +1 @@
+{ "comment": "the content of this file is irrelevant" }