Redis Cluster

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This service deploys a Redis Cluster with 6 nodes (3 masters + 3 replicas).

Services

redis-1 to redis-6: Redis cluster nodes
redis-cluster-init: Initialization container (one-time setup)

Environment Variables

Variable Name	Description	Default Value
REDIS_VERSION	Redis image version	`8.2.1-alpine`

Please modify the .env file as needed for your use case.

Volumes

redis_1_data to redis_6_data: Data persistence for each Redis node

Usage

Start Redis Cluster

# Start all Redis nodes
docker compose up -d

# Initialize the cluster (first time only)
docker compose --profile init up redis-cluster-init

# Verify cluster status
docker exec redis-1 redis-cli --cluster check redis-1:6379

Connect to Cluster

# Connect using redis-cli
docker exec -it redis-1 redis-cli -c

# Test cluster
127.0.0.1:6379> CLUSTER INFO
127.0.0.1:6379> SET mykey "Hello"
127.0.0.1:6379> GET mykey

Access from Application

Use cluster mode connection from your application:

# Python example
from redis.cluster import RedisCluster

startup_nodes = [
    {"host": "localhost", "port": "7000"},
    {"host": "localhost", "port": "7001"},
    {"host": "localhost", "port": "7002"},
]
rc = RedisCluster(startup_nodes=startup_nodes, decode_responses=True)
rc.set("foo", "bar")
print(rc.get("foo"))

Ports

7000-7005: Mapped to each Redis node's 6379 port

Cluster Information

Masters: 3 nodes (redis-1, redis-2, redis-3)
Replicas: 3 nodes (redis-4, redis-5, redis-6)
Total slots: 16384 (distributed across masters)

Adding New Nodes

To add more nodes to the cluster:

Add new service in docker-compose.yaml
Start the new node
Add to cluster:

docker exec redis-1 redis-cli --cluster add-node new-node-ip:6379 redis-1:6379
docker exec redis-1 redis-cli --cluster reshard redis-1:6379

Removing Nodes

# Remove a node
docker exec redis-1 redis-cli --cluster del-node redis-1:6379 <node-id>

Notes

Cluster initialization only needs to be done once
Each node stores a subset of the data
Automatic failover is handled by Redis Cluster
Minimum 3 master nodes required for production
Data is automatically replicated to replica nodes

Security

Add password authentication for production:

command: redis-server --requirepass yourpassword --cluster-enabled yes ...

Use firewall rules to restrict access
Consider using TLS for inter-node communication in production

License

Redis is available under the Redis Source Available License 2.0 (RSALv2). See Redis GitHub for more information.