Allow to read runtime information from zip files.

This reads metadata information generated by zip-it-and-ship-it
to send the right runtime information when uploading zipped functions.

Signed-off-by: David Calavera <[email protected]>

Author: calavera

go/internal/data/hello-world.zip

@@ -582,7 +582,11 @@ func bundle(functionDir string, observer DeployObserver) (*deployFiles, error) {
 
 		switch {
 		case zipFile(i):
-			file, err := newFunctionFile(filePath, i, jsRuntime, observer)
+			runtime, err := readZipRuntime(filePath)
+			if err != nil {
+				return nil, err
+			}
+			file, err := newFunctionFile(filePath, i, runtime, observer)
 			if err != nil {
 				return nil, err
 			}
@@ -609,6 +613,43 @@ func bundle(functionDir string, observer DeployObserver) (*deployFiles, error) {
 	return functions, nil
 }
 
+func readZipRuntime(filePath string) (string, error) {
+	zf, err := zip.OpenReader(filePath)
+	if err != nil {
+		return "", err
+	}
+	defer zf.Close()
+
+	for _, file := range zf.File {
+		if file.Name == "netlify-toolchain" {
+			fc, err := file.Open()
+			if err != nil {
+				// Ignore any errors and choose the default runtime.
+				// This preserves the current behavior in this library.
+				return jsRuntime, nil
+			}
+			defer fc.Close()
+
+			reader := bufio.NewReader(fc)
+			for {
+				line, err := reader.ReadString('\n')
+				if err != nil && err != io.EOF {
+					// Ignore any errors and choose the default runtime.
+					// This preserves the current behavior in this library.
+					return jsRuntime, nil
+				}
+
+				if strings.HasPrefix(line, "runtime=") {
+					split := strings.SplitN(line, "=", 2)
+					return split[1], nil
+				}
+			}
+		}
+	}
+
+	return jsRuntime, nil
+}
+
 func newFunctionFile(filePath string, i os.FileInfo, runtime string, observer DeployObserver) (*FileBundle, error) {
 	file := &FileBundle{
 		Name:    strings.TrimSuffix(i.Name(), filepath.Ext(i.Name())),

go/porcelain/deploy.go

@@ -130,3 +130,14 @@ func TestConcurrentFileUpload(t *testing.T) {
 		}()
 	}
 }
+
+func TestReadZipRuntime(t *testing.T) {
+	runtime, err := readZipRuntime("../internal/data/hello-world.zip")
+	if err != nil {
+		t.Fatalf("unexpected error reading zip file: %v", err)
+	}
+
+	if runtime != "rs" {
+		t.Fatalf("unexpected runtime value, expected='rs', got='%s'", runtime)
+	}
+}