Add a Docker Credentials label to store and list creds

Signed-off-by: Nassim 'Nass' Eddequiouaq <eddequiouaq.nassim@gmail.com>

credentials/credentials.go

@@ -12,11 +12,16 @@ import (
 
 // Credentials holds the information shared between docker and the credentials store.
 type Credentials struct {
+	Label string
 	ServerURL string
 	Username  string
 	Secret    string
 }
 
+// Docker credentials should be labeled as such in credential stores, this label
+// allow us to filter out non-Docker credentials at lookup
+const CredsLabel  = "Docker Credentials"
+
 // Serve initializes the credentials helper and parses the action argument.
 // This function is designed to be called from a command line interface.
 // It uses os.Args[1] as the key for the action.
@@ -72,6 +77,8 @@ func Store(helper Helper, reader io.Reader) error {
 		return err
 	}
 
+	creds.Label = CredsLabel
+
 	return helper.Add(&creds)
 }
 
@@ -133,7 +140,7 @@ func Erase(helper Helper, reader io.Reader) error {
 //List returns all the serverURLs of keys in
 //the OS store as a list of strings
 func List(helper Helper, writer io.Writer) error {
-	accts, err := helper.List()
+	accts, err := helper.List(CredsLabel)
 	if err != nil {
 		return err
 	}