If we do install gateway nodes behind load balancers on our on-prem infrastructure but want to have everything else (redis, mongodb, dashboard) in the cloud are there performance or other issues we should be aware of?
This would basically be quite close to the hybrid service you are offering. The reason for this is that we might want to have managed Redis / Mongo instead of managing those ourselves.
The hybrid service we offer will take care of dashboard, MongoDB and master redis hosting.
The gateways in your infrastructure will still need a shared local redis to use as a cache.
If this redis DB is with a cloud provider (like redis labs) then that can work well, so long as those redis endpoints are close to your gateways.
The round trip from the gateway to redis will be the biggest performance hit, so long as it’s in the same AZ/region you shouldn’t see too much impact.
Do note that many hosted redis providers rate limit the connection count, and Tyk can use many connections (a ceiling can be set), so this will need to factor into your redis provider selection as if connection attempts start to get rejected there will be a significant performance impact.
It’s worth noting that these caches can be ephemeral, and so running a shared redis in hybrid need not be too much of a problem. If using AWS, ElastiCache works very well.
Hope that helps!