Ingest has a proxy filter that reroutes ingest requests to ingest nodes when they are sent to nodes with node.ingest set to false. The filter is unit tested but we could definitely use some more testing. A qa test would be perfect but we would need to be able to set different node settings per node, which is something not yet possible in our qa test infra, which will be possible soon. Once we have that we should go ahead and write a qa multinode test for this.