Support read data from stdin

pkg/loader/compose/compose.go

@@ -18,14 +18,10 @@ package compose
 
 import (
 	"fmt"
-	"io/ioutil"
 	"reflect"
 	"strings"
 
-	yaml "gopkg.in/yaml.v2"
-
-	"bufio"
-	"os"
+	"gopkg.in/yaml.v2"
 
 	"github.com/docker/libcompose/project"
 	"github.com/fatih/structs"
@@ -34,6 +30,9 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
+//
+var StdinData []byte
+
 // Compose is docker compose file loader, implements Loader interface
 type Compose struct {
 }
@@ -182,7 +181,7 @@ func (c *Compose) LoadFile(files []string) (kobject.KomposeObject, error) {
 			return kobject.KomposeObject{}, err
 		}
 		return komposeObject, nil
-	// Use docker/cli for 3
+		// Use docker/cli for 3
 	case "3", "3.0", "3.1", "3.2", "3.3":
 		komposeObject, err := parseV3(files)
 		if err != nil {
@@ -200,16 +199,10 @@ func getVersionFromFile(file string) (string, error) {
 		Version string `json:"version"` // This affects YAML as well
 	}
 	var version ComposeVersion
-	var loadedFile []byte
-	var err error
-	if file == "-" {
-		data := bufio.NewScanner(os.Stdin)
-		loadedFile = data.Bytes()
-	} else {
-		loadedFile, err = ioutil.ReadFile(file)
-		if err != nil {
-			return "", err
-		}
+	loadedFile, err := ReadFile(file)
+
+	if err != nil {
+		return "", err
 	}
 
 	err = yaml.Unmarshal(loadedFile, &version)

pkg/loader/compose/utils.go

@@ -17,6 +17,7 @@ limitations under the License.
 package compose
 
 import (
+	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -115,3 +116,18 @@ func handleServiceType(ServiceType string) (string, error) {
 func normalizeServiceNames(svcName string) string {
 	return strings.Replace(svcName, "_", "-", -1)
 }
+
+// ReadFile read data from file or stdin
+func ReadFile(fileName string) ([]byte, error) {
+	if fileName == "-" {
+		if StdinData == nil {
+			data, err := ioutil.ReadAll(os.Stdin)
+			StdinData = data
+			return data, err
+		} else {
+			return StdinData, nil
+		}
+	}
+	return ioutil.ReadFile(fileName)
+
+}

pkg/loader/compose/v3.go

@@ -17,7 +17,6 @@ limitations under the License.
 package compose
 
 import (
-	"io/ioutil"
 	"strconv"
 	"strings"
 	"time"
@@ -77,7 +76,7 @@ func parseV3(files []string) (kobject.KomposeObject, error) {
 	var config *types.Config
 	for _, file := range files {
 		// Load and then parse the YAML first!
-		loadedFile, err := ioutil.ReadFile(file)
+		loadedFile, err := ReadFile(file)
 		if err != nil {
 			return kobject.KomposeObject{}, err
 		}