feat: suppress the output of createApp

A git push requires that the first four bytes should be the line length, so not suppressing the output results in a partially failed deploy.

https://stackoverflow.com/a/8175315/1515875

plugins/apps/functions.go

@@ -155,5 +155,7 @@ func maybeCreateApp(appName string) error {
 		return fmt.Errorf("Re-enable app auto-creation or create an app with 'dokku apps:create %s'", appName)
 	}
 
-	return createApp(appName)
+	return common.SuppressOutput(func() error {
+		return createApp(appName)
+	})
 }

plugins/common/common.go

@@ -18,6 +18,8 @@ import (
 	sh "github.com/codeskyblue/go-sh"
 )
 
+type errfunc func() error
+
 // ShellCmd represents a shell command to be run for dokku
 type ShellCmd struct {
 	Env           map[string]string
@@ -533,6 +535,25 @@ func StripInlineComments(text string) string {
 	return strings.TrimSpace(string(bytes))
 }
 
+// SuppressOutput suppresses the output of a function unless there is an error
+func SuppressOutput(f errfunc) error {
+	rescueStdout := os.Stdout
+	r, w, _ := os.Pipe()
+	os.Stdout = w
+
+	err := f()
+
+	w.Close()
+	out, _ := ioutil.ReadAll(r)
+	os.Stdout = rescueStdout
+
+	if err != nil {
+		fmt.Printf(string(out[:]))
+	}
+
+	return err
+}
+
 // ToBool returns a bool value for a given string
 func ToBool(s string) bool {
 	return s == "true"