So, there was already a post about this six months ago, but we just came across it, too.
We added a dataless, masterless node to our cluster for searches, and it didn't work. It couldn't query, couldn't even _cat/nodes. It's logs said it couldn't find the master.
Ok, we checked various things for like 3 days, when we hit upon installing the 'license' plugin.
We had this plugin installed it on our data nodes for 'marvel-agent', but only used a trial license, and let it lapse. To be clear, we don't have a real license. Just the plugin.
[2016-01-29 17:09:33,179][INFO ][license.plugin.core ] [R01] license [03f97e89-ad45-4e51-9d6d-ac1552518e4f] - expired
So anyway, on the search node, we installed 'license' and all of a sudden everything was grand! But, what the heck? Why is that!?
Is that working as intended? If so, could we get that in the documentation someplace? "BTW, if you have 'license' installed elsewhere..." If it's not, should this be a bug?