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Initializing a Kronotop Cluster

Redis compability​

Kronotop supports both RESP2 and RESP3 wire protocols, allowing you to use any Redis client to access the cluster and query transactional data structures like Bucket and ZMap.

This document assumes that you have already installed redis-cli and Docker on your system.

Installing Kronotop via Docker​

It's easy to try Kronotop with Docker Compose:

curl -o kronotop-demo.yaml https://raw.githubusercontent.com/kronotop/kronotop/refs/heads/main/docker/kronotop-demo.yaml

Then, you can run the following command to create a single-member Kronotop cluster for demonstration purposes:

docker compose -f kronotop-demo.yaml up

If everything goes okay, you should be able to connect to the primary node via redis-cli:

redis-cli -p 3320 -c
127.0.0.1:3320> PING
PONG

A cluster member serves from two ports:

  • 5484 for the client communication,
  • 3320 for the internal traffic and administrative commands.

Setting up the cluster metadata​

Before using Kronotop in your project, you first need to initialize the cluster. KR.ADMIN INITIALIZE-CLUSTER command creates the cluster's layout on the FoundationDB and initializes the cluster:

127.0.0.1:3320> KR.ADMIN INITIALIZE-CLUSTER
OK

Then, we must set the shard's primary ownership and make the shards operable. Currently, we only have a running Kronotop instance in the cluster. It's good enough for demonstration purposes. We can assign all shards to this member.

First, we should run KR.ADMIN DESCRIBE-MEMBER command to learn id of the current member:

127.0.0.1:3320> KR.ADMIN DESCRIBE-MEMBER
1# member_id => a0dc14d811a285834c187ddc20549de7c1c1a381
2# status => RUNNING
3# process_id => AAAOz0CfYCoAAAAA
4# external_host => 127.0.0.1
5# external_port => (integer) 5484
6# internal_host => 127.0.0.1
7# internal_port => (integer) 3320
8# latest_heartbeat => (integer) 8227

We need member_id from this response. The following command sets the primary owner of all Redis shards;

127.0.0.1:3320> KR.ADMIN ROUTE SET PRIMARY REDIS * a0dc14d811a285834c187ddc20549de7c1c1a381
OK

Now we are ready to make our all Redis shards writable:

127.0.0.1:3320> KR.ADMIN SET-SHARD-STATUS REDIS * READWRITE
OK

If everything is okay, we can start using the newly formed Kronotop cluster:

First try​

redis-cli -p 5484 -c
127.0.0.1:5484> SET mykey "Hello"
OK
127.0.0.1:5484> GET mykey
"Hello"

All in-memory data will be persisted and replicated by the storage engine. See Storage Engine section for the details.