Support for basic http auth in internal solr requests

We want to protect any HTTP-resource (url). We want to require credentials no matter what kind of HTTP-request you make to a Solr-node.

It can faily easy be acheived as described on http://wiki.apache.org/solr/SolrSecurity. This problem is that Solr-nodes also make "internal" request to other Solr-nodes, and for it to work credentials need to be provided here also.

Ideally we would like to "forward" credentials from a particular request to all the "internal" sub-requests it triggers. E.g. for search and update request.

But there are also "internal" requests

• that only indirectly/asynchronously triggered from "outside" requests (e.g. shard creation/deletion/etc based on calls to the "Collection API")
• that do not in any way have relation to an "outside" "super"-request (e.g. replica synching stuff)

We would like to aim at a solution where "original" credentials are "forwarded" when a request directly/synchronously trigger a subrequest, and fallback to a configured "internal credentials" for the asynchronous/non-rooted requests.

In our solution we would aim at only supporting basic http auth, but we would like to make a "framework" around it, so that not to much refactoring is needed if you later want to make support for other kinds of auth (e.g. digest)

We will work at a solution but create this JIRA issue early in order to get input/comments from the community as early as possible.