DEMO VERSION WARNING:
THIS PROJECT IS A DEMO ON HOW TO MANIPULATE REDIS CLUSTER WITH PYTHON SOCKET, WITH UNSTABLE API, LACK OF TESTS. AND IT DOES NOT SUPPORT SIMULTANEOUS OPERATIONS ON ONE CLUSTER.
Install
pip install redis-trib
easy_install redis-trib
Start a cluster in a single redis node (the node should have cluster enabled)
redis-trib.py start NODE_HOST:PORT
Add another master node to a cluster
redis-trib.py join CLUSTER_HOST:PORT NEW_NODE_HOST:PORT
Add a slave node to a master (slave should not in any cluster)
redis-trib.py replicate MASTER_HOST:PORT SLAVE_HOST:PORT
Remove a node from its cluster
redis-trib.py quit NODE_HOST:PORT
Shutdown an empty cluster (there is only one node left and no keys in the node)
redis-trib.py shutdown NODE_HOST:PORT
Fix a migrating slot in a node
redis-trib.py fix HOST_HOST:PORT
The above APIs balance slots automatically and not configurable.
The Python API
import redistrib.command
# start cluster at node 127.0.0.1:7000
redistrib.command.start_cluster('127.0.0.1', 7000)
# add node 127.0.0.1:7001 to the cluster as a master
redistrib.command.join_cluster('127.0.0.1', 7000, '127.0.0.1', 7001)
# add node 127.0.0.1:7002 to the cluster as a slave to 127.0.0.1:7000
redistrib.command.replicate('127.0.0.1', 7000, '127.0.0.1', 7002)
# remove node 127.0.0.7000 from the cluster
redistrib.command.quit_cluster('127.0.0.1', 7000)
# shut down the cluster
redistrib.command.shutdown_cluster('127.0.0.1', 7001)
# fix a migrating slot in a node
redistrib.command.fix_migrating('127.0.0.1', 7001)
See also https://github.com/antirez/redis/blob/3.0/src/redis-trib.rb
The join_cluster function takes 2 optional arguments balancer and balance_plan. The former is an object for calculating the weights of cluster nodes, and the latter is a function that calculates how the slots migrate to balance the load between nodes.
As crude examples, you could refer to redistrib.clusternode.BaseBalancer and redistrib.clusternode.base_balance_plan. An instance of BaseBalancer should implement weight method that returns the weight of a specified node, and a function like base_balance_plan should return a list of migration tuples (source node, destination node, slots count).