This example uses site-to-site to send logs from one instance to another using a push model:
https://github.com/bbende/nifi-streaming-examples
The first instance has a Remote Process Group pointing to the URL of the second instance.
The second instance has an Input Port to receive logs, which the Remote Process Group from the first instance is connected to.
You also need to enable nifi.remote.input.socket.port and nifi.remote.input.secure on the node where the an incoming connection will be made. In this example that is the node with the Input Port which will receive an incoming connection from the Remote Process Group on the first node.