Copy target + replace (mirrord for Teams feature proposal)

[Razz4780]

Source issue

Without the copy_target feature, mirrord does not stop the remote application from making outgoing connections. In some scenarios, this is not acceptable, as we end up with more connections in the system than expected (+1 from the local application).

Feature proposal

Right now copy_target either:

1. Simply spawns an extra pod (and we have n+1 connections in the system)
2. Spawns the extra pod, but also scales down the target workload (and we have just 1 connection in the system)

Ideally, we'd like to have the same amount of connections in the system. This could be achieved by transparently replacing one of the workload's pods.

Config

Replace any pod from the workload:

{
  "features": {
    "copy_target": {
      "replace": true
    }
  }
}

Replace an exact pod:

{
  "features": {
    "copy_target": {
      "replace": "target-pod-name"
    }
  }
}

[linear]

MBE-1370 Copy target + replace (mirrord for Teams feature proposal)