...

This should be improved. New output of improved re-balance rebalance ("–rebalance" command) algorithm should suite following requirements:

...

• design an algorithm matching the above requirements;
• implement this algorithm and unit tests;
• test it manually using different initial assignments;

Rebalance command

New command "--rebalance" is proposed to be added.
The usage scenario is same as for "--generate" except new command is called "--rebalance".

Scenario:
1. User generates reassignment configuration by running:
--rebalance --topics-to-move-json-file topics.json --broker-list 0,1,2 --zookeeper zk:2181
2. User copies proposed reassignment configuration to reassignment.json file
3. User executes reassignment by running:
--execute --reassignment-json-file reassignment.json --zookeeper zk:2181
4. User verifies status of reassignment by running:
--verify --reassignment-json-file reassignment.json --zookeeper zk:2181

Decommission broker command

...

To preserve compatibility old "–generate" command (using old algorithm) is still present. New "–rebalance" command (invoking new re-balance rebalance algorithm) is added.

• What impact (if any) will there be on existing users?
  No impact. Old "–generate" command is preserved for compatibility.
  

...