feat(stacks): prevent name collision with external stacks (#16)

* feat(stacks): check for name collision within external stacks

* feat(stacks): check for name collisions

* feat(stacks): check for running stacks

* feat(stacks): change name collision message

* feat(stack): check for existing services only on swarm

* fix(http): supply docker factory to handler

* feat(stacks): look at all containers

api/http/handler/stacks/stack_start.go

@@ -2,6 +2,7 @@ package stacks
 
 import (
 	"errors"
+	"fmt"
 	"net/http"
 
 	httperrors "github.com/portainer/portainer/api/http/errors"
@@ -45,6 +46,15 @@ func (handler *Handler) stackStart(w http.ResponseWriter, r *http.Request) *http
 		return &httperror.HandlerError{http.StatusForbidden, "Permission denied to access endpoint", err}
 	}
 
+	isUnique, err := handler.checkUniqueName(endpoint, stack.Name, stack.ID, stack.SwarmID != "")
+	if err != nil {
+		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to check for name collision", err}
+	}
+	if !isUnique {
+		errorMessage := fmt.Sprintf("A stack with the name '%s' is already running", stack.Name)
+		return &httperror.HandlerError{http.StatusConflict, errorMessage, errors.New(errorMessage)}
+	}
+
 	resourceControl, err := handler.DataStore.ResourceControl().ResourceControlByResourceIDAndType(stack.Name, portainer.StackResourceControl)
 	if err != nil {
 		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to retrieve a resource control associated to the stack", err}