Redis cluster construction practice

Redis is an open source in-memory data storage system, commonly used in cache, message queue, Key-Value database and other scenarios. In large-scale application scenarios, a single Redis machine may not be able to meet the demand. In this case, a Redis cluster needs to be built to improve the availability and scalability of the system. This article will introduce the actual process of building a Redis cluster.

1. Environment preparation

Before setting up a Redis cluster, you need to prepare the environment first. In this article, we use 4 CentOS 7.6 virtual machines as Redis nodes. The configuration of each virtual machine is as follows:

CPU: 1 core

Memory: 2GB

Hard disk: 20GB

Next we need to install Redis, we use Install using source code compilation method. Download Redis:

wget http://download.redis.io/releases/redis-5.0.8.tar.gz

Unzip Redis:

tar -zxvf redis-5.0.8.tar.gz

Enter the Redis directory:

cd redis-5.0.8

Compile Redis:

make

Install Redis:

make install

After the installation is completed, the Redis configuration file redis.conf needs to be configured on each machine. The following is an example of a configuration file:

bind 127.0.0.1
protected-mode no
port 6379
daemonize yes
pidfile /var/run/redis_6379.pid
logfile "/var/log/redis/redis.log"
dir /var/lib/redis/6379

Among them, bind indicates the bound IP address; protected-mode indicates whether to enable protected mode; port indicates the port number used by Redis; daemonize indicates whether to start as a daemon process; pidfile represents the process ID file path; logfile represents the log file path; dir represents the Redis data file storage path.

2. Build a Redis cluster

After preparing the Redis environment of each machine, we need to form them into a Redis cluster. The Redis cluster adopts the master-slave replication mode, and each node will have a slave node of the corresponding node for data backup.

The following is an example of how we build a Redis cluster:

a) Create a configuration file

First, we need to create a configuration file redis-cluster in each Redis node. conf, the sample configuration is as follows:

port 6379
cluster-enabled yes
cluster-config-file nodes.conf
cluster-node-timeout 15000
daemonize yes
pidfile /var/run/redis_6379.pid
logfile "/var/log/redis/redis.log"
dir /var/lib/redis/6379

Among them, cluster-enabled means turning on the cluster mode; cluster-config-file means the storage file of node information; cluster-node-timeout means the timeout; other parameters are the same as the configuration of Redis document.

b) Start the Redis node

Next, we need to start the Redis service in each Redis node, use the following command:

redis-server /etc/redis/redis-cluster.conf

c) Create a cluster

In all Redis nodes, execute the following command:

redis-cli --cluster create node1_IP:6379 node2_IP:6379 node3_IP:6379 node4_IP:6379 --cluster-replicas 1

Among them, node1_IP:6379 node2_IP:6379 node3_IP:6379 node4_IP:6379 represents the IP address and port number of the Redis node; --cluster-replicas represents each Each node has 1 slave node for data backup. After the execution is completed, the Redis cluster is successfully established.

3. Testing the Redis Cluster

After the Redis cluster is built, we need to test to ensure that the cluster is working properly. The following is the test process:

a) Connect to the Redis cluster

Use the following command to connect to the Redis cluster:

redis-cli -c -h node1_IP -p 6379

Among them, -c means to connect in cluster mode; -h means to connect in cluster mode The IP address of the Redis node; -p indicates the port number used by Redis.

b) View cluster information

Use the following command to view cluster information:

cluster info

c) Write test data

Use the following command to Redis cluster Write test data:

set test "redis cluster test"

d) Read test data

Use the following command to read test data from the Redis cluster:

get test

Perform the above operation, if it succeeds If the test data is read, the Redis cluster is successfully established.

4. Summary

The process of building a Redis cluster is relatively simple, but you need to pay attention to the correctness of the configuration file and cluster commands. When using Redis cluster, you also need to pay attention to the load condition of the nodes and the reliability of data backup to improve the availability and scalability of the cluster.

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