NewQuerierHandler returns a HTTP handler that can be used by the querier service to either register with the frontend worker query processor or with the external HTTP server to fulfill the Prometheus query API.

HTTPHeaderMiddleware adds specified HTTPHeaders to the request context.

IndexPageContent is a map of sections to path -> description.

Ingester is defined as an interface to allow for alternative implementations of ingesters to be passed into the API.RegisterIngester() method.

DistributorPushWrapper wraps around a push.