Cluster architecture in Redis - Mini Project: Build & Apply

Redis Cluster Architecture Basics

📖 Scenario: You are setting up a Redis cluster to manage a distributed cache system for a growing web application. This cluster will help store and retrieve user session data efficiently across multiple Redis nodes.

🎯 Goal: Build a simple Redis cluster configuration with three nodes, assign slots to each node, and verify the cluster setup.

📋 What You'll Learn

Create a Redis cluster configuration with exactly three nodes

Assign hash slots to each node correctly

Use Redis CLI commands to check cluster nodes and slots

Ensure the cluster nodes are connected and communicating

💡 Why This Matters

🌍 Real World

Redis clusters are used in real-world applications to provide high availability and scalability for caching and session management.

💼 Career

Understanding Redis cluster setup and management is valuable for backend developers and system administrators working with distributed caching and high-performance data stores.

1

Create Redis nodes configuration

Create three Redis node configuration files named redis-node-7000.conf, redis-node-7001.conf, and redis-node-7002.conf. Each file should have the line port 7000, port 7001, and port 7002 respectively, and include cluster-enabled yes to enable clustering.

Redis

# Create redis-node-7000.conf with 'port 7000' and 'cluster-enabled yes'
# Create redis-node-7001.conf with 'port 7001' and 'cluster-enabled yes'
# Create redis-node-7002.conf with 'port 7002' and 'cluster-enabled yes'

Need a hint?

Each Redis node configuration file must specify its unique port and enable clustering with cluster-enabled yes.

2

Start Redis nodes and create cluster

Start the three Redis nodes on ports 7000, 7001, and 7002 using the configuration files. Then, use the Redis CLI command redis-cli --cluster create 127.0.0.1:7000 127.0.0.1:7001 127.0.0.1:7002 --cluster-replicas 0 to create the cluster without replicas.

Redis

port 7000
cluster-enabled yes

# redis-node-7001.conf
port 7001
cluster-enabled yes

# redis-node-7002.conf
port 7002
cluster-enabled yes

# Start Redis nodes and create cluster with redis-cli --cluster create command

Need a hint?

Use redis-server to start each node with its config file. Then run the redis-cli --cluster create command with all node addresses and --cluster-replicas 0 to create the cluster without replicas.

3

Assign hash slots to nodes

Verify that the cluster has assigned hash slots evenly across the three nodes. Use the Redis CLI command redis-cli -p 7000 cluster slots to check the slot allocation.

Redis

port 7000
cluster-enabled yes

# redis-node-7001.conf
port 7001
cluster-enabled yes

# redis-node-7002.conf
port 7002
cluster-enabled yes

# Start Redis nodes:
redis-server redis-node-7000.conf
redis-server redis-node-7001.conf
redis-server redis-node-7002.conf

# Create cluster:
redis-cli --cluster create 127.0.0.1:7000 127.0.0.1:7001 127.0.0.1:7002 --cluster-replicas 0

# Check cluster slots with redis-cli -p 7000 cluster slots

Need a hint?

Use redis-cli -p 7000 cluster slots to see how slots are distributed among the nodes.

4

Verify cluster nodes and connectivity

Use the Redis CLI command redis-cli -p 7000 cluster nodes to list all nodes in the cluster and verify they are connected and communicating properly.

Redis

port 7000
cluster-enabled yes

# redis-node-7001.conf
port 7001
cluster-enabled yes

# redis-node-7002.conf
port 7002
cluster-enabled yes

# Start Redis nodes:
redis-server redis-node-7000.conf
redis-server redis-node-7001.conf
redis-server redis-node-7002.conf

# Create cluster:
redis-cli --cluster create 127.0.0.1:7000 127.0.0.1:7001 127.0.0.1:7002 --cluster-replicas 0

# Verify slot allocation:
redis-cli -p 7000 cluster slots

# Check cluster nodes with redis-cli -p 7000 cluster nodes

Need a hint?

Run redis-cli -p 7000 cluster nodes to see all cluster nodes and their status.