Fix cancel tasks API

[joelvim]

Elasticsearch provides two ways to cancel a task

• by its id : POST _tasks/oTUltX4IQMOUUVeiohTt8A:12345/_cancel
• by node & actions : POST _tasks/_cancel?nodes=nodeId1,nodeId2&actions=*reindex

Elastic4s which takes nodeIds and actions, provides a single interface for both, but both are broken :

• if no node id is provided, the endpoint returned is s"/_tasks/cancel" while it should be s"/_tasks/_cancel"
• if node ids are provided, it returns s"/_tasks/task_id:${request.nodeIds.mkString(",")}/_cancel" but this URL is invalid for two reasons:
  • task_id in the path breaks the task id that is provided,
  • the API does not support more than one task.
    Both result in a 400 with "reason": "malformed task id task_id:<my_task_id>"

As the handler always returns a Right override def handle(response: HttpResponse) = Right(response.statusCode >= 200 && response.statusCode < 300) this API always fail silently.

My solution is to provide a new API cancelTaskById(taskId: String) to prevent ambiguities from the use of the other API that becomes a pure nodeIds + actions API.