Install and Configure Redis on Ubuntu for Local Object Cache

Redis is often used as a local object cache for WordPress and other web applications. It can reduce repeated database work by keeping frequently used values in memory.

This guide shows how to install Redis on Ubuntu, bind it to local addresses, set a memory limit, choose an eviction policy, validate memory, and restart the service.

What the Script Does

The deployment script this article is based on:

• Installs redis-server.
• Enables the Redis service.
• Backs up /etc/redis/redis.conf.
• Sets bind address, port, memory limit, eviction policy, backlog, and timeout.
• Keeps protected mode enabled.
• Runs a Redis memory test.
• Restarts and verifies the Redis service.

Install Redis

Run:

sudo apt update
sudo apt install -y redis-server
sudo systemctl enable redis-server

Check the service:

sudo systemctl status redis-server

Back Up the Redis Config

Before editing Redis, create a backup:

sudo mkdir -p /opt/server-backups/redis
timestamp="$(date +%Y%m%d%H%M%S)"
sudo cp /etc/redis/redis.conf "/opt/server-backups/redis/redis.conf.before.${timestamp}.bak"

Apply Local Cache Settings

This example uses Redis as a local service:

• Bind address: 127.0.0.1 ::1
• Port: 6379
• Max memory: 2gb
• Eviction policy: allkeys-lru
• Protected mode: yes

Apply the settings:

sudo sed -i "s/^bind .*/bind 127.0.0.1 ::1/" /etc/redis/redis.conf
sudo sed -i "s/^port .*/port 6379/" /etc/redis/redis.conf
sudo sed -i "s/^# maxmemory .*/maxmemory 2gb/" /etc/redis/redis.conf
sudo sed -i "s/^# maxmemory-policy .*/maxmemory-policy allkeys-lru/" /etc/redis/redis.conf
sudo sed -i "s/^tcp-backlog .*/tcp-backlog 511/" /etc/redis/redis.conf
sudo sed -i "s/^timeout .*/timeout 0/" /etc/redis/redis.conf

Make sure protected mode is enabled:

sudo grep -q "^protected-mode yes" /etc/redis/redis.conf || echo "protected-mode yes" | sudo tee -a /etc/redis/redis.conf >/dev/null

For a single-server WordPress setup, binding Redis to localhost is usually the right default. Do not expose Redis directly to the public internet.

Test and Restart Redis

Run a basic memory test:

sudo redis-server /etc/redis/redis.conf --test-memory 2 >/dev/null

Back up the after-change config:

sudo cp /etc/redis/redis.conf "/opt/server-backups/redis/redis.conf.after.${timestamp}.bak"

Restart Redis:

sudo systemctl restart redis-server
sudo systemctl is-active --quiet redis-server

Test with redis-cli:

redis-cli ping

Expected output:

PONG

Full Script

Here is the full Bash script used for this Redis install and local object-cache workflow:

#!/usr/bin/env bash

__show_script_usage() {
  cat <<'__SCRIPT_USAGE__'
# Install-Redis.sh

Installs and configures Redis for local WordPress object caching.

## Example Usage

```bash
cd /opt/DevOps/Scripts
sudo bash ./Install-Redis.sh
```

## Notes

This changes Redis configuration, writes backups under `/opt/DevOps/Backups/Redis`, and restarts Redis.
__SCRIPT_USAGE__
}

if [[ "${BASH_SOURCE[0]}" == "$0" ]]; then
  case "${1:-}" in
    -h|--help|--usage)
      __show_script_usage
      exit 0
      ;;
  esac
fi

REDIS_BIND_ADDRESS="127.0.0.1 ::1"
REDIS_PORT="6379"
REDIS_MAXMEMORY="2gb"
REDIS_MAXMEMORY_POLICY="allkeys-lru"
REDIS_TCP_BACKLOG="511"
REDIS_TIMEOUT="0"

DEVOPS_BACKUP_DIR="/opt/DevOps/Backups/Redis"

set -euo pipefail

echo "Installing and configuring Redis..."

if [ "$EUID" -ne 0 ]; then
    echo "ERROR: Run with sudo."
    exit 1
fi

apt update
apt install -y redis-server

systemctl enable redis-server

mkdir -p "${DEVOPS_BACKUP_DIR}"

cp /etc/redis/redis.conf "${DEVOPS_BACKUP_DIR}/redis.conf.before.$(date +%Y%m%d%H%M%S).bak"

sed -i "s/^bind .*/bind ${REDIS_BIND_ADDRESS}/" /etc/redis/redis.conf
sed -i "s/^port .*/port ${REDIS_PORT}/" /etc/redis/redis.conf
sed -i "s/^# maxmemory .*/maxmemory ${REDIS_MAXMEMORY}/" /etc/redis/redis.conf
sed -i "s/^# maxmemory-policy .*/maxmemory-policy ${REDIS_MAXMEMORY_POLICY}/" /etc/redis/redis.conf
sed -i "s/^tcp-backlog .*/tcp-backlog ${REDIS_TCP_BACKLOG}/" /etc/redis/redis.conf
sed -i "s/^timeout .*/timeout ${REDIS_TIMEOUT}/" /etc/redis/redis.conf

grep -q "^protected-mode yes" /etc/redis/redis.conf || echo "protected-mode yes" >> /etc/redis/redis.conf

cp /etc/redis/redis.conf "${DEVOPS_BACKUP_DIR}/redis.conf.after.$(date +%Y%m%d%H%M%S).bak"

redis-server /etc/redis/redis.conf --test-memory 2 >/dev/null

systemctl restart redis-server
systemctl is-active --quiet redis-server

echo "Redis install complete."

Troubleshooting

If Redis will not restart, check:

sudo systemctl status redis-server
sudo journalctl -u redis-server -xe

If redis-cli ping fails, confirm Redis is listening on the expected address and port:

ss -ltnp | grep 6379

Quick Reference

sudo apt install -y redis-server
sudo systemctl enable redis-server
sudo systemctl restart redis-server
redis-cli ping

Redis is powerful, but keep it local unless you have a specific secured network design. For WordPress object caching on one server, localhost Redis is usually enough.