Deploying Redis

Introduction

Remote Dictionary Server (Redis) is an open-source, in-memory, distributed, and durable key-value pair storage database written in C. Redis is a storage system with rich functions and applies to various scenarios, including caching, session storage, rankings, and real-time analysis. It is widely used and has active community support. This tutorial describes how you can deploy Redis in HCE 2.0.

Preparations

Prepare two ECSs and assign a public IP address or EIP to each ECS. One ECS functions as the master Redis node, and the other serves as the slave Redis node.

Ensure that inbound security group rules allow traffic to flow to the ECSs over port 6379.

Procedure

Install and configure Redis.

Run the following command on the two ECSs to install Redis:
```
dnf install redis -y
```
Run the following command on the two ECSs to start Redis:
```
systemctl start redis
```
To set Redis to automatically enable upon system boot, run the following command:
```
systemctl enable redis
```
Run the following command to check the Redis status:
```
systemctl status redis
```
If active (running) is displayed, Redis is started.

On the master node, edit the /etc/redis.conf file and configure the following attributes:

bind 0.0.0.0        # Replace the value with the IP address of the master node. In this example, enter any IP address.
requirepass ******* # Set a password.

On the slave node, edit the /etc/redis.conf file and configure the following attributes:

bind 0.0.0.0                        # Replace the value with the IP address of the slave node. In this example, enter any IP address.
requirepass *******                 # Set a password.
slaveof <IP address of the master node> <Port of the master node>
masterauth <Password of the master node>

Run the following command on the two ECSs to restart Redis:
```
systemctl restart redis
```

Verify Redis.

Run the following command on the master node to connect to Redis:
```
redis-cli
auth <Password>
```

Run the following command to view the node information:

127.0.0.1:6379> info replication
# Replication
role:master
connected_slaves:1
slave0:ip=x.x.x.x,port=6379,state=online,offset=4382,lag=0
master_replid:5d68ccf7722f461cc5f004c7e96fd7c506990508
master_replid2:0000000000000000000000000000000000000000
master_repl_offset:4382
second_repl_offset:-1
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:1
repl_backlog_histlen:4382
127.0.0.1:6379>