Merge pull request #190 from marcov/better-failmsg

Improve duplicate name error message on container create

containers.go

@@ -2,6 +2,7 @@ package storage
 
 import (
 	"encoding/json"
+	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -278,7 +279,8 @@ func (r *containerStore) Create(id string, names []string, image, layer, metadat
 	names = dedupeNames(names)
 	for _, name := range names {
 		if _, nameInUse := r.byname[name]; nameInUse {
-			return nil, ErrDuplicateName
+			return nil, errors.Wrapf(ErrDuplicateName,
+				fmt.Sprintf("the container name \"%s\" is already in use by \"%s\". You have to remove that container to be able to reuse that name.", name, r.byname[name].ID))
 		}
 	}
 	if err == nil {