simple ETag handling

[jprante]

Hi Elasticsearch team!

I hacked a simple ETag handling. It's not tested, but it should do.

See discussion https://groups.google.com/forum/?fromgroups=#!topic/elasticsearch/aEjjxQzUhdM

Jörg

[synhershko]

This is rather costly. Can there be a softer version, to be used in more idle indexes where no many updates are happening, where the etag value is associated with index updates (vs computed against the actual content)?

[jprante]

Yes. I think one possibility is enabling ETags per REST action, I have to add it.

[jprante]

Now, ETag caching can be enabled in the config only per REST action class, e.g. http.cache.etag.restsearchaction: true

The header will look like

HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Content-Length: 661
ETag: 4173176557

[jprante]

Suppressing ETags on a per index or per type basis is another interesting thing, yes. This depends on the REST action. This needs some work in the RestUtils I guess. And I have to find out if ETag cacheable setting via cluster update API works.

[jprante]

Oops.

[clintongormley]

Closing this issue given that there has been no support for this, and it is easier to implement client side.