What is Redis:
Redis is a caching system that works by temporarily storing information in a key-value data structure. Redis is popular because it is available in almost all major programming languages. By caching data, Redis can speed up the process of retrieving information. When a user requests information that is not cached, Redis will fetch the data from the database and return it to the user.
Redis is an open source, in-memory data structure store, used as a database, cache, and message broker. It supports data structures such as strings, hashes, lists, sets, sorted sets with range queries, bitmaps, hyperloglogs, and geospatial indexes with radius queries.
Redis has built-in replication, Lua scripting, LRU eviction, transactions and different levels of on-disk persistence.
Redis is used as a database by web applications such as WordPress and Drupal. It is also used for object caching by platforms such as Magento.
In this step-by-step guide, I will walk you through the steps to install Redis Server on CentOS 7. CentOS requires that you run through yum to install Redis Server from the official repository.
Step 1 – Prerequisites:
- You just need to have a running CentOS 7 any dedicated server or virtual server with the root account.
Step 2 – Update the Operating System:
- First, you need to upgrade the system using yum update.
[[email protected] ~]# yum update Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile epel/x86_64/metalink | 8.4 kB 00:00 * base: centos.excellmedia.net * epel: mirror2.totbb.net * extras: centos.excellmedia.net * updates: centos.excellmedia.net base | 3.6 kB 00:00 extras | 2.9 kB 00:00 kubernetes/signature | 454 B 00:00 kubernetes/signature | 1.4 kB 00:00 !!! puppetlabs-pc1 | 2.5 kB 00:00 updates | 2.9 kB 00:00 No packages marked for update
Step 3 – Install the Redis Server:
- After your machine is updated, you need to update redis with the yum install redis command.
[[email protected] ~]# yum install redis Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * base: centos.excellmedia.net * epel: mirrors.webcare360.com * extras: centos.excellmedia.net * updates: centos.excellmedia.net Resolving Dependencies --> Running transaction check ---> Package redis.x86_64 0:3.2.12-2.el7 will be installed --> Processing Dependency: libjemalloc.so.1()
(64bit) for package: redis-3.2.12-2.el7.x86_64 --> Running transaction check ---> Package jemalloc.x86_64 0:3.6.0-1.el7 will be installed --> Finished Dependency Resolution .......................................................
Step 4 – Configuration of Redis Server
- Access this command in the Redis configuration file through the supervised directive. Change the value from “no” to “systemd”.
[[email protected]~]# cat /etc/redis.conf | grep -i supervise # supervised no - no supervision interaction # supervised upstart - signal upstart by putting Redis into SIGSTOP mode # supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET # supervised auto - detect upstart or systemd method based on supervised systemd
Step 5 – Restart the Redis Server:
- Restart the redis service by using systemctl restart redis command once the configuration file is updated.
[[email protected]~]# systemctl restart redis
Do check the status of the Redis Service is checked when it’s restarted.
[[email protected] ~]# systemctl status redis ● redis.service - Redis persistent key-value database Loaded: loaded (/usr/lib/systemd/system/redis.service; disabled; vendor preset: disabled) Drop-In: /etc/systemd/system/redis.service.d └─limit.conf Active: active (running) since Mon 2019-12-09 16:48:29 EST; 6s ago Main PID: 3655 (redis-server) CGroup: /system.slice/redis.service └─3655 /usr/bin/redis-server 127.0.0.1:6379 Dec 09 16:48:29 localhost systemd: Starting Redis persistent key-value database... Dec 09 16:48:29 localhost systemd: Started Redis persistent key-value database.
Step 6 – Test Redis Server:
After the installation and the configuration of Redis server following these installation steps, you will need to test Redis connection by giving a key value pair using the set command in redis-cli. Here we can post the value WebCare360 to hello key. When we try to access the value of hello key, we will discover WebCare360 in the output.
[[email protected]~]# redis-cli 127.0.0.1:6379> set hello webcare360 OK 127.0.0.1:6379> get hello "webcare360"
Reference: Redis Documentation