Cross-cluster/Tribe search between 2.x and newer

Elastic Stack Elasticsearch
1

We have big Elasticsearch 2.x cluster which can't be upgraded right now, and I was working with cross-cluster search between 2.x and 6.x.
I tried 5.x as cross-cluster (and tribe), it works with 5 and 6, but it doesn't connect to 2. Even 5.0.0 doesn't.

I know that 2 is very old now and should be upgraded, but I'm searching for a temporary solution for cross-search between Elasticsearch 2.x and newer versions.

Did anyone have this problem? Third-party solutions like kind of proxying is also ok for me.

This solution is temporary, I think this cluster can be upgraded (the problem is we can't have downtime now, but upgrade from 2.x to any newer needs full cluster restart).

2

If you feel very creative (I mean very, very creative) you could figure out the compatibility matrix and setup ES tribe node accordingly. I have no idea if this could work as there are all sorts of breaking changes between 2.x and 6.x index and mapping wise but it could be fun to test it.

So you could end up with your 2.x <- max compat version 4 <- max compat version 5 <- version 6. (You might need some in between steps).

Again, just something I thought about while reading your post. If it doesn't make sense please ignore it.

Paul.