Redis

What is Redis?

Redis is an open-source, in-memory data structure store that can be used as a database, cache, and message broker. It supports various data structures such as strings, hashes, lists, sets, and sorted sets. Redis is known for its high performance, scalability, and flexibility, making it a popular choice for caching and real-time analytics.

Install

Ubuntu

> apt update
> sudo apt install redis-server
> sudo nano /etc/redis/redis.conf

If you want to install the latest version of Redis, you can use the following commands:

> curl -fsSL https://packages.redis.io/gpg | sudo gpg --dearmor -o /usr/share/keyrings/redis-archive-keyring.gpg
> echo "deb [signed-by=/usr/share/keyrings/redis-archive-keyring.gpg] https://packages.redis.io/deb $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/redis.list
> sudo apt-get update
> sudo apt-get install redis

Service

Open /etc/redis/redis.conf and update the following settings:

# If you run Redis from upstart or systemd, Redis can interact with your
# supervision tree. Options:
#   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
#                        UPSTART_JOB or NOTIFY_SOCKET environment variables
# Note: these supervision methods only signal "process is ready."
#       They do not enable continuous liveness pings back to your supervisor.
supervised no

Change supervised no to supervised systemd, then save and exit the file.

Restart the Redis service:

> sudo systemctl restart redis

Enable Redis to start on boot:

> sudo systemctl enable redis

Remote Access

To allow remote access to Redis, you need to update the bind setting in the Redis configuration file:

> sudo nano /etc/redis/redis.conf

Comment out the bind setting:

#bind 127.0.0.1 ::1

Modify the protected-mode setting to no:

protected-mode no

Save and exit the file, then restart the Redis service:

> sudo systemctl restart redis

Enable Password Authentication

To enable password authentication in Redis, you need to set a password in the Redis configuration file:

> sudo nano /etc/redis/redis.conf

Uncomment the requirepass setting and set a password:

requirepass your_password_here

Pay attention to the password length and complexity. Redis has an extremely fast response speed, capable of handling 150,000 brute-force password attempts per second. Therefore, we need to set a very strong password for Redis. We can generate a password using OpenSSL:

> openssl rand 60 | openssl base64 -A

#return
RBOJ9cCNoGCKhlEBwQLHri1g+atWgn4Xn4HwNUbtzoVxAYxkiYBi7aufl4MILv1nxBqR4L6NNzI0X6cE

Use the generated password as the value for requirepass, then save and exit the file.

Restart the Redis service:

> sudo systemctl restart redis

FAQ

redis-server.service: Can't open PID file /run/redis/redis-server.pid (yet?) after start: Operation not permitted

This error occurs when the Redis service is unable to create the PID file due to permission issues. To resolve this, you need to update the Redis service configuration:

> sudo nano /etc/systemd/system/redis.service

Add the ExecStop and PIDFile to the [Service] section:

[Service]
Type=notify
ExecStart=/usr/bin/redis-server /etc/redis/redis.conf
ExecStop=/bin/kill -s TERM $MAINPID
PIDFile=/run/redis/redis-server.pid
TimeoutStopSec=0
Restart=always
User=redis
Group=redis
RuntimeDirectory=redis
RuntimeDirectoryMode=2755