add gcs

detect.go

@@ -26,6 +26,7 @@ func init() {
 		new(GitDetector),
 		new(BitBucketDetector),
 		new(S3Detector),
+		new(GCSDetector),
 		new(FileDetector),
 	}
 }

detect_gcs.go

@@ -0,0 +1,37 @@
+package getter
+
+import (
+	"fmt"
+	"net/url"
+	"strings"
+)
+
+// GCSDetector implements Detector to detect GCS URLs and turn
+// them into URLs that the GCSGetter can understand.
+type GCSDetector struct{}
+
+func (d *GCSDetector) Detect(src, _ string) (string, bool, error) {
+	if len(src) == 0 {
+		return "", false, nil
+	}
+
+	if strings.Contains(src, "googleapis.com/") {
+		return d.detectHTTP(fmt.Sprintf("https://www.googleapis.com/%s",
+			strings.SplitN(src, "googleapis.com/", 2)[1]))
+	}
+
+	return "", false, nil
+}
+
+func (d *GCSDetector) detectHTTP(src string) (string, bool, error) {
+	url, err := url.Parse(src)
+	if err != nil {
+		return "", false, fmt.Errorf("error parsing GCS URL: %s", err)
+	}
+
+	pathParts := strings.SplitN(url.Path, "/", 5)
+	if len(pathParts) != 5 {
+		return "", false, fmt.Errorf("URL is not a valid GCS URL")
+	}
+	return "gcs::" + url.String(), true, nil
+}

get.go

@@ -67,6 +67,7 @@ func init() {
 	Getters = map[string]Getter{
 		"file":  new(FileGetter),
 		"git":   new(GitGetter),
+		"gcs":   new(GCSGetter),
 		"hg":    new(HgGetter),
 		"s3":    new(S3Getter),
 		"http":  httpGetter,

get_gcs.go

@@ -0,0 +1,170 @@
+package getter
+
+import (
+	"context"
+	"fmt"
+	"net/url"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"cloud.google.com/go/storage"
+	"google.golang.org/api/iterator"
+)
+
+// GCSGetter is a Getter implementation that will download a module from
+// a GCS bucket.
+type GCSGetter struct {
+	getter
+}
+
+func (g *GCSGetter) ClientMode(u *url.URL) (ClientMode, error) {
+	ctx := g.Context()
+
+	// Parse URL
+	bucket, object, err := g.parseURL(u)
+	if err != nil {
+		return 0, err
+	}
+
+	sctx := context.Background()
+	client, err := storage.NewClient(sctx)
+	if err != nil {
+		return 0, err
+	}
+	iter := client.Bucket(bucket).Objects(ctx, &storage.Query{Prefix: object})
+	count := 0
+	for {
+		_, err := iter.Next()
+		if err != nil && err != iterator.Done {
+			return 0, err
+		}
+		count++
+		if err == iterator.Done {
+			break
+		}
+	}
+	if count <= 1 {
+		// Return file if there are no matches as well.
+		// GetFile will fail in this case.
+		return ClientModeFile, nil
+	} else {
+		return ClientModeDir, nil
+	}
+}
+
+func (g *GCSGetter) Get(dst string, u *url.URL) error {
+	ctx := g.Context()
+
+	// Parse URL
+	bucket, object, err := g.parseURL(u)
+	if err != nil {
+		return err
+	}
+
+	// Remove destination if it already exists
+	_, err = os.Stat(dst)
+	if err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	if err == nil {
+		// Remove the destination
+		if err := os.RemoveAll(dst); err != nil {
+			return err
+		}
+	}
+
+	// Create all the parent directories
+	if err := os.MkdirAll(filepath.Dir(dst), 0755); err != nil {
+		return err
+	}
+
+	sctx := context.Background()
+	client, err := storage.NewClient(sctx)
+	if err != nil {
+		return err
+	}
+
+	// Iterate through all matching objects.
+	iter := client.Bucket(bucket).Objects(ctx, &storage.Query{Prefix: object})
+	for {
+		obj, err := iter.Next()
+		if err != nil && err != iterator.Done {
+			return err
+		}
+		if err == iterator.Done {
+			break
+		}
+
+		// Get the object destination path
+		objDst, err := filepath.Rel(object, obj.Name)
+		if err != nil {
+			return err
+		}
+		objDst = filepath.Join(dst, objDst)
+		// Download the matching object.
+		err = g.getObject(ctx, client, objDst, bucket, obj.Name)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (g *GCSGetter) GetFile(dst string, u *url.URL) error {
+	ctx := g.Context()
+
+	// Parse URL
+	bucket, object, err := g.parseURL(u)
+	if err != nil {
+		return err
+	}
+
+	sctx := context.Background()
+	client, err := storage.NewClient(sctx)
+	if err != nil {
+		return err
+	}
+	return g.getObject(ctx, client, dst, bucket, object)
+}
+
+func (g *GCSGetter) getObject(ctx context.Context, client *storage.Client, dst, bucket, object string) error {
+	rc, err := client.Bucket(bucket).Object(object).NewReader(ctx)
+	if err != nil {
+		return err
+	}
+	defer rc.Close()
+
+	// Create all the parent directories
+	if err := os.MkdirAll(filepath.Dir(dst), 0755); err != nil {
+		return err
+	}
+
+	f, err := os.Create(dst)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	_, err = Copy(ctx, f, rc)
+	return err
+}
+
+func (g *GCSGetter) parseURL(u *url.URL) (bucket, path string, err error) {
+	if strings.Contains(u.Host, "googleapis.com") {
+		hostParts := strings.Split(u.Host, ".")
+		if len(hostParts) != 3 {
+			err = fmt.Errorf("URL is not a valid GCS URL")
+			return
+		}
+
+		pathParts := strings.SplitN(u.Path, "/", 5)
+		if len(pathParts) != 5 {
+			err = fmt.Errorf("URL is not a valid GCS URL")
+			return
+		}
+		bucket = pathParts[3]
+		path = pathParts[4]
+	}
+	return
+}