cdep: prompt on branch override (#772)

tools/cdep/app/add_config.go

@@ -57,7 +57,10 @@ func (a App) AddToConfig(path, branchName, commitHash string) (bool, error) {
 }
 
 func (a App) doJsonUpdates(path string, branchName string, commitHash string, blob []byte) []byte {
-	attemptWarnIfOverride(blob, branchRegAdd, branchName, path)
+	override := promptIfOverride(blob, branchRegAdd, branchName, path)
+	if !override {
+		return blob
+	}
 
 	blob = attemptUpdate(blob, commitRegAdd, "commit", commitHash)
 	blob = attemptUpdate(blob, branchRegAdd, "branch", branchName)
@@ -68,7 +71,10 @@ func (a App) doJsonUpdates(path string, branchName string, commitHash string, bl
 }
 
 func (a App) doYamlUpdates(path string, branchName string, commitHash string, blob []byte) []byte {
-	attemptWarnIfOverride(blob, branchRegAddYaml, branchName, path)
+	override := promptIfOverride(blob, branchRegAddYaml, branchName, path)
+	if !override {
+		return blob
+	}
 
 	imagePrefix := "master"
 	if branchName != "master" {
@@ -133,16 +139,21 @@ func attemptUpdateYaml(blob []byte, reg *regexp.Regexp, key, value string) []byt
 	return blob
 }
 
-func attemptWarnIfOverride(blob []byte, reg *regexp.Regexp, newBranch, path string) {
+func promptIfOverride(blob []byte, reg *regexp.Regexp, newBranch, path string) bool {
 	matches := reg.FindSubmatch(blob)
 
 	if len(matches) <= 1 {
-		return
+		return true
 	}
 
 	branchName := string(matches[1])
 
 	if branchName != "master" && branchName != newBranch {
 		log.Warnf("Custom branch is going to be overriden, old: %s, new: %s, path: %s", branchName, newBranch, path)
+		override := boolPrompt("Override branch?")
+
+		return override
 	}
+
+	return true
 }

tools/cdep/app/prompt.go

@@ -0,0 +1,22 @@
+package app
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
+
+// boolPrompt asks for a bool value using the label
+func boolPrompt(label string) bool {
+	var s string
+	r := bufio.NewReader(os.Stdin)
+	for {
+		fmt.Fprint(os.Stderr, label+" (y/n) ")
+		s, _ = r.ReadString('\n')
+		if s != "" {
+			break
+		}
+	}
+	return strings.TrimSpace(s) == "y"
+}