---++  GET api/instance/triage/:entity-type/:entity-name
   * <a href="#Description">Description</a>
   * <a href="#Parameters">Parameters</a>
   * <a href="#Results">Results</a>
   * <a href="#Examples">Examples</a>

---++ Description
Given a feed/process instance this command traces it's ancestors to find what all ancestors have failed. It's useful if
lot of instances are failing in a pipeline as it then finds out the root cause of the pipeline being stuck.


---++ Parameters
   * :entity-type type of entity(feed/process).
   * :entity-name name of the feed/process.
   * :start instance time of the entity instance.
   * :colo <optional param> name of the colo on which you want to triage

---++ Results
It returns a json graph

---++ Examples
---+++ Rest Call
<verbatim>
GET http://localhost:15000/api/instance/triage/feed/my-feed?start=2015-03-02T00:00Z&colo=local
</verbatim>
---+++ Result
<verbatim>
{
    "vertices": ["(FEED) my-feed (2015-03-02T00:00Z) [Unavailable]", "(PROCESS) producer-process (2015-03-01T10:00Z) [TIMEDOUT]", "(FEED) input-feed-for-producer (2015-03-01T00:00Z) [Available]"],
    "edges":
    [
        {
         "from"  : "(PROCESS) producer-process (2015-03-01T10:00Z) [TIMEDOUT]",
         "to"    : "(FEED) my-feed (2015-03-02T00:00Z) [Unavailable]",
         "label" : "produces"
        },
        {
         "from"  : "(FEED) input-feed-for-producer (2015-03-01T00:00Z) [Available]",
         "to"    : "(PROCESS) producer-process (2015-03-01T10:00Z) [TIMEDOUT]",
         "label" : "consumed by"
        }
    ]
}
</verbatim>