Redis is an open-source, in-memory data structure store that serves as a database, cache, and message broker. Whether you need to speed up your web application with session caching, implement real-time messaging with publish/subscribe patterns, or store frequently accessed data for instant retrieval, Redis provides the performance and flexibility to handle these workloads efficiently. Consequently, by the end of this guide, you will have a fully configured Redis installation with optional password authentication, memory limits for caching, and firewall rules for secure network access.
This guide covers two installation methods: Debian’s default repository for a stable, distribution-tested version, and the official Redis.io repository for the latest features. Importantly, both approaches work on Debian 11 Bullseye, Debian 12 Bookworm, and Debian 13 Trixie.
Update System and Install Prerequisites
Update Debian System Packages
Before installing Redis or any other software, the initial step is to ensure your system’s packages are up-to-date. Additionally, this critical preliminary step helps mitigate potential conflicts during the subsequent installation process. Furthermore, it ensures that all system dependencies are current, minimizing potential issues arising from outdated software packages.
In a Debian system, you can do this by running the following command in the terminal:
sudo apt update && sudo apt upgradeInstall Prerequisites
Next, install the packages required for adding the Redis.io repository. Specifically, these provide SSL certificate validation, file downloading, GPG key handling, and release codename detection:
sudo apt install curl ca-certificates gnupg lsb-release -yChoose Your Redis Installation Method
You can install Redis using Debian’s default repositories or the official Redis.io repository. To help you decide, the following table summarizes the key differences:
| Method | Channel | Version | Updates | Best For |
|---|---|---|---|---|
| Debian Repository | Debian Packages | Distribution default | Automatic via apt upgrade | Users who prefer stable, distribution-tested packages |
| Redis.io Repository | Official Redis | Latest stable | Automatic via apt upgrade | Users who need the latest features and security patches |
For most users, the Redis.io repository is recommended because it provides the latest stable releases with up-to-date security patches. On the other hand, the Debian default packages are suitable for environments where distribution-level stability testing is a priority.
Redis versions vary across Debian releases: Debian 11 includes Redis 6.0.x, Debian 12 includes Redis 7.0.x, and Debian 13 includes Redis 8.0.x. The Redis.io repository provides Redis 7.4.x on Debian 11 and Redis 8.4.x on Debian 12/13, giving you access to newer features than the default packages.
Option 1: Install Redis from Debian Repository
The Debian default repository provides a stable, distribution-tested version of Redis. Moreover, this method requires no additional repository configuration and receives security updates through standard system upgrades.
To begin, install Redis using the default repository:
sudo apt install redis-serverAfter installation, verify the package source and version:
apt-cache policy redis-serverredis-server:
Installed: 5:x.x.x
Candidate: 5:x.x.x
Version table:
*** 5:x.x.x 500
500 http://deb.debian.org/debian [your-release]/main amd64 Packages
Next, enable and start the Redis service:
sudo systemctl enable redis-server --nowOption 2: Install Redis from Redis.io Repository
The Redis.io repository provides the latest stable releases directly from the Redis project. As a result, this method gives you access to new features and security patches as soon as they are released.
Import the GPG Key
First, download and store the GPG key used to verify package authenticity:
curl -fsSL https://packages.redis.io/gpg | sudo gpg --dearmor -o /usr/share/keyrings/redis-archive-keyring.gpgAdd the Repository
Next, create the repository configuration using the modern DEB822 .sources format:
cat <<EOF | sudo tee /etc/apt/sources.list.d/redis.sources
Types: deb
URIs: https://packages.redis.io/deb
Suites: $(lsb_release -cs)
Components: main
Architectures: $(dpkg --print-architecture)
Signed-By: /usr/share/keyrings/redis-archive-keyring.gpg
EOFDebian 13 defaults to DEB822
.sourcesfor APT entries. Debian 12 and Debian 11 fully support.sources, though legacy.listfiles remain common on older installations.
Update Package Index and Install Redis
After adding the repository, refresh the package index and install Redis:
sudo apt update
sudo apt install redisThe Redis.io repository provides a
redismetapackage that depends onredis-server. Both package names work for installation; the service name isredis-serverregardless of which package you install.
Verify the Installation Source
Confirm that Redis was installed from the Redis.io repository rather than the Debian default:
apt-cache policy redisredis:
Installed: 6:x.x.x-1rl1~[your-release]1
Candidate: 6:x.x.x-1rl1~[your-release]1
Version table:
*** 6:x.x.x-1rl1~[your-release]1 500
500 https://packages.redis.io/deb [your-release]/main amd64 Packages
The output confirms installation from packages.redis.io. Next, enable the Redis service to start automatically at boot:
sudo systemctl enable redis-server --nowFinally, verify that Redis is running:
systemctl status redis-server● redis-server.service - Advanced key-value store
Loaded: loaded (/lib/systemd/system/redis-server.service; enabled; preset: enabled)
Active: active (running)
Main PID: 1234 (redis-server)
Tasks: 5 (limit: 4644)
Memory: 7.2M
CPU: 123ms
CGroup: /system.slice/redis-server.service
└─1234 /usr/bin/redis-server 127.0.0.1:6379
Additionally, confirm the installed Redis version:
redis-server --versionRedis server v=8.x.x sha=00000000:0 malloc=jemalloc-5.3.0 bits=64 build=...
Test the Redis Connection
Check Listening Ports
By default, Redis listens on localhost port 6379. To confirm this, verify that Redis is actively listening:
ss -tlnp | grep redisLISTEN 0 511 127.0.0.1:6379 0.0.0.0:* users:(("redis-server",pid=1234,fd=6))
Ping the Redis Server
The simplest way to verify Redis is responding to commands is with a ping test. To do this, connect to Redis using the command-line interface:
redis-cliOnce connected, send a ping command:
pingPONG
The PONG response confirms Redis is running and accepting connections. When finished, exit the Redis CLI:
exitConfigure Redis
Redis provides flexible configuration options for caching, network access, and authentication. The following sections cover the most common settings.
Open the Configuration File
Redis stores its configuration in /etc/redis/redis.conf. To begin editing, open this file with a text editor:
sudo nano /etc/redis/redis.confSet Memory Limits for Caching
When using Redis as a cache, set a memory limit to prevent unbounded growth. To do this, add or modify these directives in the configuration file:
maxmemory 500mb
maxmemory-policy allkeys-lruThis example allocates 500 MB of memory for Redis. Adjust this value based on your server’s specifications and your application’s requirements.
Subsequently, once the assigned memory reaches capacity, Redis will remove keys following the Least Recently Used (LRU) policy.
Configure Network Binding
By default, Redis listens only on the localhost interface. However, you can modify the bind directive to allow connections from other addresses.
Option 1: Bind to All Interfaces
To allow Redis to listen on all network interfaces, simply modify the bind directive:
bind 0.0.0.0Binding Redis to all interfaces exposes it to network access. Therefore, always enable password authentication before making Redis accessible from other hosts.
Option 2: Bind to a Specific IP Address
To bind Redis to a specific IP address, simply specify the address directly:
bind 192.168.1.100Alternatively, you can also bind to multiple addresses by listing them:
bind 127.0.0.1 192.168.1.100Enable Password Authentication
For added security, require password authentication for Redis connections. To do this, locate the requirepass directive, uncomment it by removing the leading #, and set a strong password:
requirepass YourStrongPasswordHereReplace YourStrongPasswordHere with a strong password that includes a mix of uppercase and lowercase letters, numbers, and special symbols.
Apply Configuration Changes
After making changes, save the file (Ctrl + O) and exit nano (Ctrl + X). Next, restart Redis to apply the new settings:
sudo systemctl restart redis-serverFinally, verify that Redis restarted successfully:
sudo systemctl status redis-serverConfigure a Firewall for Redis with UFW
If Redis needs to accept connections from other hosts, you should configure UFW (Uncomplicated Firewall) to control which IP addresses can access the Redis port.
Install UFW
If UFW is not already installed, add it with APT. Additionally, for detailed configuration options, see the UFW installation guide for Debian.
sudo apt install ufw -yEnable UFW with SSH Access
First, before enabling UFW, allow SSH connections to prevent being locked out of your server:
sudo ufw allow OpenSSHIf you are managing a remote server via SSH, always run
sudo ufw allow OpenSSHbeforesudo ufw enable. Enabling UFW without allowing SSH first will disconnect your session and lock you out.
With SSH access secured, enable the firewall:
sudo ufw enableAdd Redis Firewall Rules
Configure UFW to allow Redis connections only from trusted sources. Specifically, the following examples show common configurations.
Allow a Single IP Address
For instance, to allow Redis connections from a specific server (for example, your application server at 192.168.1.50):
sudo ufw allow proto tcp from 192.168.1.50 to any port 6379Allow a Subnet
Alternatively, for a cluster where multiple servers need Redis access, allow an entire subnet (for example, 192.168.1.0/24):
sudo ufw allow proto tcp from 192.168.1.0/24 to any port 6379Allowing subnet access trusts all devices on that network. Therefore, only use this option on secured internal networks.
Verify Firewall Rules
After adding rules, verify the UFW configuration:
sudo ufw status numberedStatus: active
To Action From
-- ------ ----
[ 1] OpenSSH ALLOW IN Anywhere
[ 2] 6379/tcp ALLOW IN 192.168.1.50
Next, test Redis connectivity from an allowed host:
redis-cli -h 192.168.1.100 pingPONG
As expected, a PONG response confirms that the firewall rules are working and Redis is accepting connections.
Additional Configuration Options
Redis provides additional configuration options for performance tuning and monitoring. In particular, the following examples cover common settings.
Configure Key Eviction Policy
When Redis reaches its memory limit, the maxmemory-policy setting controls how keys are evicted. Additionally, the maxmemory-samples setting determines how many keys Redis samples when making eviction decisions. To configure these settings, open the configuration file:
sudo nano /etc/redis/redis.confLook for the maxmemory-policy setting and configure it to your liking. For instance, if you wish to establish a policy that expires keys according to the Least Recently Used (LRU) algorithm, then update the configuration as such:
maxmemory-policy volatile-lruNext, locate the maxmemory-samples setting. Importantly, this will dictate the number of samples that Redis should review to arrive at the eviction decision:
maxmemory-samples 5Enable TCP Keepalive
Activating TCP keepalive can aid in detecting and closing idle connections, which in turn releases valuable system resources. To enable it, locate the tcp-keepalive setting in the /etc/redis/redis.conf file:
tcp-keepalive 300In this example, we set the keepalive interval to 300 seconds. However, you should adjust this figure according to your server’s requirements and conditions.
Configure Slow Log Monitoring
Slow logs provide a valuable mechanism for pinpointing performance issues. Specifically, they do so by logging queries that exceed a specified duration. To configure slow logs, find the slowlog-log-slower-than and slowlog-max-len settings in the /etc/redis/redis.conf file:
slowlog-log-slower-than 10000
slowlog-max-len 128The above example sets the slowlog threshold to 10,000 microseconds (equivalent to 10 milliseconds). Additionally, the slow log will maintain the 128 most recent entries. However, you should adjust these values to match your specific requirements and conditions.
Enable Event Notifications
Redis can create notifications for specific events, providing a powerful tool for monitoring and debugging. To activate event notifications, locate the notify-keyspace-events setting in the /etc/redis/redis.conf file:
notify-keyspace-events ExAHere, we configure Redis to dispatch notifications for expired and evicted keys. For more information, the official Redis documentation is a comprehensive resource on event notifications and available choices.
Adjust the Logging Level
To better troubleshoot and monitor Redis, change its logging level. Specifically, you can do this in the /etc/redis/redis.conf file by adjusting the loglevel setting:
loglevel noticeThe default logging level is set to ‘notice’. Other available options include ‘debug’, ‘verbose’, and ‘warning’. Choose the level that best suits your monitoring needs.
Apply Configuration Changes
After modifying any of the above settings, save the configuration file and restart Redis to apply the changes:
sudo systemctl restart redis-serverNext, verify that Redis restarted successfully and is running with the updated configuration:
systemctl status redis-server● redis-server.service - Advanced key-value store
Loaded: loaded (/lib/systemd/system/redis-server.service; enabled; preset: enabled)
Active: active (running)
Troubleshoot Common Redis Issues
Despite careful configuration, issues can arise. Therefore, this section covers common Redis problems and their solutions.
Redis Service Fails to Start After Config Changes
If Redis fails to start after editing the configuration file, the most common cause is a syntax error. To diagnose this, check the Redis logs for details:
sudo journalctl -u redis-server --no-pager -n 20Look for lines containing “Fatal” or “Error” in the log output. Typically, common issues include invalid directive names, missing quotation marks around values with spaces, or incorrect memory size formats.
Once identified, fix any reported errors in the configuration file, and then restart Redis:
sudo systemctl restart redis-server
systemctl status redis-serverConnection Refused from Remote Hosts
If remote clients receive “Connection refused” errors, check the bind address. By default, Redis only listens on localhost (127.0.0.1). Therefore, to verify the current bind setting:
grep "^bind" /etc/redis/redis.confTo allow remote connections, update the bind directive to include the server’s IP address or 0.0.0.0 for all interfaces. Importantly, remember to enable password authentication before exposing Redis to the network, and then add appropriate UFW firewall rules as shown earlier in this guide.
Authentication Errors After Enabling Password
If you receive NOAUTH Authentication required errors after enabling password authentication, simply connect to Redis with the password:
redis-cli -a YourPasswordHereAlternatively, you can authenticate after connecting:
redis-cli
AUTH YourPasswordHereOK
Remove Redis from Debian
If you no longer need Redis, you can remove it completely from your system. First, stop the Redis service:
sudo systemctl stop redis-server
sudo systemctl disable redis-serverNext, remove Redis and its associated packages:
sudo apt remove --purge redis redis-server redis-tools -y
sudo apt autoremove -yAdditionally, if you installed Redis from the Redis.io repository, remove the repository configuration and GPG key:
sudo rm /etc/apt/sources.list.d/redis.sources
sudo rm /usr/share/keyrings/redis-archive-keyring.gpg
sudo apt updateWarning: The following command permanently deletes the Redis data directory (
/var/lib/redis), log directory (/var/log/redis), and configuration directory (/etc/redis). This removes all cached values, database dumps, and custom configurations. Export any important data before proceeding.
sudo rm -rf /var/lib/redis /var/log/redis /etc/redisFinally, verify that Redis has been removed:
apt-cache policy redis-serverredis-server: Installed: (none) Candidate: x.x.x Version table:
The Installed: (none) status confirms Redis has been removed. However, the Candidate version may still appear if the Debian default repository is still configured.
Conclusion
You now have Redis installed and configured on Debian, with options for memory limits, password authentication, network binding, and firewall rules. Moving forward, for production environments, consider setting up SSH on Debian for secure remote management, and explore integrating Redis with web servers like Nginx on Debian or application stacks using PHP on Debian. Furthermore, for additional caching options, see the Memcached guide for Debian.
