How to install Redis server on CentOS 7

Redis is an open source multi-platform data storage software written in ANSI C. Redis can support Lua, C, Java, Python, Perl, PHP and many other languages.

Building Redis

redis currently does not have an official RPM installation package. We need to compile from source code, and in order to compile, we need to install Make and GCC.

If GCC and Make have not been installed, use yum to install them.

yum install gcc make

Download the tar compressed package from the official website.

curl http://download.redis.io/releases/redis-3.0.4.tar.gz -o redis-3.0.4.tar.gz

Unzip.

tar zxvf redis-3.0.4.tar.gz

Enter the decompressed directory.

cd redis-3.0.4

Use Make to compile source files.

make

Installation

Enter the directory of the source file.

cd src

Copy the Redis server and client to /usr/local/bin.

cp redis-server redis-cli /usr/local/bin

It is best to copy sentinel, benchmark and check.

cp redis-sentinel redis-benchmark redis-check-aof redis-check-dump /usr/local/bin

Create redis configuration folder.

mkdir /etc/redis

Create a valid directory to save data under /var/lib/redis

mkdir -p /var/lib/redis/6379

System parameters

In order for redis to work properly, some kernel parameters need to be configured.

Configure vm.overcommit_memory to 1, which can avoid data being truncated. See here for details.

sysctl -w vm.overcommit_memory=1

Modify the maximum number of backlog connections to exceed the tcp-backlog value in redis.conf, which is the default value of 511. More information about sysctl-based IP network tunneling can be found at kernel.org.

sysctl -w net.core.somaxconn=512

Cancel support for transparent huge pages, because this will cause delays and memory access problems during the use of redis.

echo never > /sys/kernel/mm/transparent_hugepage/enabled

redis.conf

redis.conf is the configuration file of redis. However, you will see that the name of this file is 6379.conf, and this number is the network port that redis listens on. To run multiple redis instances, the following naming scheme is recommended.

Copy the sample redis.conf to /etc/redis/6379.conf.

cp redis.conf /etc/redis/6379.conf

Now edit this file and configure parameters.

vi /etc/redis/6379.conf

daemonize

Set daemonize to no, systemd needs it to run in the foreground, otherwise redis will hang suddenly.

daemonize no

pidfile

Set pidfile to /var/run/redis_6379.pid.

pidfile /var/run/redis_6379.pid

port

If you do not plan to use the default port, you can modify it.

port 6379

loglevel

Set the log level.

loglevel notice

logfile

Modify the log file path.

logfile /var/log/redis_6379.log

dir

Set the directory to /var/lib/redis/6379

dir /var/lib/redis/6379

Security

There are several operations that can improve security.

Unix sockets

Because the client program and the server program usually run on the same machine, there is no need to listen to the network socket. If this is similar to your use case, you can use a unix socket instead of a network socket. To do this, you need to configure port to 0, and then configure the following options to enable the unix socket.

Set the socket file of unix socket.

 unixsocket /tmp/redis.sock

Restrict the permissions of socket files.

unixsocketperm 700

Now in order for redis-cli to be accessible, the -s parameter should be used to point to the socket file.

redis-cli -s /tmp/redis.sock

requirepass

You may need remote access, if so, then you should set a password so that it is required before each operation.

requirepass "bTFBx1NYYWRMTUEyNHhsCg"

rename-command

Imagine the output of the following command. Yes, this will output the server's configuration, so you should deny this access whenever possible.

CONFIG GET *

You can use the "rename-command" command to limit or prohibit the use of this or other instructions. You must provide a command name and an alternative name. To make it safer to ban a command, its alternative name should be set to an empty string so that no one can guess the name of the command.

rename-command FLUSHDB "FLUSHDB_MY_SALT_G0ES_HERE09u09u"rename-command FLUSHALL ""rename-command CONFIG "CONFIG_MY_S4LT_GO3S_HERE09u09u"

Use password to access through unix socket, and modify the command

Snapshot

By default, redis The data set will be periodically dumped to the dump.rdb file in the directory we set. You can configure the frequency of dumps using the save command, whose first parameter is the time frame in seconds and the second parameter is the number of modifications to be made on the data file.

Every 15 minutes and the key has been modified at least once.

save 900 1

Every 5 minutes and the key has been modified at least 10 times.

save 300 10

Every 1 minute and the key has been modified at least 10,000 times.

save 60 10000

The file /var/lib/redis/6379/dump.rdb contains the dump data of the in-memory dataset since the last save. Because it first creates a temporary file and then replaces the previous dump file, there is no problem of data corruption. You don't have to worry, you can just copy the file.

Start at boot

You can use systemd to add redis to the system boot list.

Copy the example init_script file to /etc/init.d, pay attention to the port number represented by the script name.

cp utils/redis_init_script /etc/init.d/redis_6379

Now we want to use systemd, so create a unit file named redis_6379.service under /etc/systems/system.

vi /etc/systemd/system/redis_6379.service

Fill in the following content, see systemd.service for details.

[Unit]Description=Redis on port 6379[Service]Type=forkingExecStart=/etc/init.d/redis_6379 startExecStop=/etc/init.d/redis_6379 stop[Install]WantedBy=multi-user.target

现在添加我之前在 /etc/sysctl.conf 里面修改过的内存过量使用和 backlog 最大值的选项。

vm.overcommit_memory = 1net.core.somaxconn=512

对于透明巨页内存支持，并没有直接 sysctl 命令可以控制，所以需要将下面的命令放到 /etc/rc.local 的结尾。

echo never > /sys/kernel/mm/transparent_hugepage/enabled

这样就可以启动了，通过设置这些选项你就可以部署 redis 服务到很多简单的场景，然而在 redis.conf 还有很多为复杂环境准备的 redis 选项。在一些情况下，你可以使用 replication 和 Sentinel 来提高可用性，或者将数据分散在多个服务器上，创建服务器集群。

什么是Linux系统

Linux是一种免费使用和自由传播的类UNIX操作系统，是一个基于POSIX的多用户、多任务、支持多线程和多CPU的操作系统，使用Linux能运行主要的Unix工具软件、应用程序和网络协议。

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