GET _warmer should return a 404 for warmers that do not exist

[Mpdreamz]

Doing the following in any of the 0.90 releases

curl -XPOST "http://localhost:9200/my-new-index"
curl -XGET "http://localhost:9200/my-new-index/_warmer/this-warmer-does-not-exists"

Will result in:

{
   "error": "IndexWarmerMissingException[index_warmer [this-warmer-does-not-exists] missing]",
   "status": 404
}

However in the 1.0 GA release the latter returns a 200 with the following body:

{}

[Mpdreamz]

Ok so this seems to be according to the spec:

Similarly, the return values for GET have been unified with the following rules:

Only return values that exist. If you try to GET a mapping which doesn’t exist, 
then the result will be an empty object: {}. We no longer throw a 404 if the requested 
mapping/warmer/alias/setting doesn’t exist.

from: http://www.elasticsearch.org/guide/en/elasticsearch/reference/master/_indices_apis.html

Can anyone explain the reason for this behaviour?

[grantr]

This seems odd to me as well. Why return a 200 response when retrieving an object that doesn't exist? This is an obvious place to return a 404.

Returning a 200 directly contradicts the behavior of indices-exists: http://www.elasticsearch.org/guide/en/elasticsearch/reference/master/indices-exists.html#indices-exists

Warmers should support a similar exists api with the HEAD verb.

[javanna]

I agree that the get warmer api should be changed to return 404 when the warmer doesn't exist.

[jpountz]

Closing: warmers will go away in 3.0 #15614