Kong runs at a critical point in any infrastructure. Having any sort of downtime is usually unacceptable.

To avoid downtime due to Kong upgrades, Kong now supports a blue-green deployment method where for two Kong nodes of version A and version A+1 can run together at the same time as the upgrade is being rolled out, and then switching all traffic to A+1.

Kong has a migrations framework that handles them for you. If you're doing a migration because you're upgrading from an older version of Kong you'll want to do that only once the Kong nodes are upgraded.

For example, here are the instructions on upgrading to 1.0, which walk you through a couple migrations scenarios. https://discuss.konghq.com/t/kong-1-0-is-now-generally-avail...

Check out the Upgrade Path here: https://github.com/Kong/kong/blob/master/UPGRADE.md