In production environments, you can precisely control the distribution of traffic that lands on a particular shard. When dealing with large numbers of instances, you can use the relative scale of individual shards to implement percentage based traffic. That combines well with a proxy shard, which forwards or splits the traffic it receives to a separate service or application running elsewhere.
In the simplest configuration, the proxy forwards requests unchanged. In more complex setups, you can duplicate the incoming requests and send to both a separate cluster as well as to a local instance of the application, and compare the result. Other patterns include keeping the caches of a DR installation warm, or sampling incoming traffic for analysis purposes.
Any TCP (or UDP) proxy could be run under the desired shard. Use the oc scale
command to alter the relative number of instances serving requests under the
proxy shard. For more complex traffic management, consider customizing the
{product-title} router with proportional balancing capabilities.