install_redis.sh

#!/usr/bin/env bash

# Ensure the script is run as root or with sudo
if [ "$(id -u)" != "0" ]; then
    echo "Please run this script as root (sudo)."
    exit 1
fi

read -sp "Enter the desired Redis password: " REDIS_PASS
echo

# 1. Stop and purge any existing Redis installation
systemctl stop redis-server || true
apt purge redis-server redis-tools -y
apt autoremove -y

# 2. Reinstall Redis
apt update
apt install redis-server -y

# At this point, Redis should be installed with default config.
# Check if it starts in its default form:
systemctl restart redis-server
if ! systemctl is-active --quiet redis-server; then
    echo "Redis failed to start with default configuration."
    echo "Check 'systemctl status redis-server' and 'journalctl -xeu redis-server.service' for details."
    exit 1
fi

echo "Redis started successfully with default configuration."

# 3. Now that Redis starts successfully, make minimal config changes:
REDIS_CONF="/etc/redis/redis.conf"

# Set a password
# If requirepass is commented by default, uncomment it:
sed -i 's/^# requirepass .*/requirepass '"$REDIS_PASS"'/' $REDIS_CONF
# If not found, append:
grep -q "^requirepass" $REDIS_CONF || echo "requirepass $REDIS_PASS" >> $REDIS_CONF

# Bind to all interfaces
sed -i 's/^bind .*/bind 0.0.0.0/' $REDIS_CONF

# Disable protected mode
sed -i 's/^protected-mode .*/protected-mode no/' $REDIS_CONF

# No need to alter supervised or daemonize since the package defaults should be correct
# Maxmemory settings can be added if needed:
# echo "maxmemory 256mb" >> $REDIS_CONF
# echo "maxmemory-policy allkeys-lru" >> $REDIS_CONF

# 4. Restart Redis to apply changes
systemctl restart redis-server
if systemctl is-active --quiet redis-server; then
    echo "Redis installation and configuration completed successfully."
    echo
    echo "To test the connection from your local machine:"
    echo "1. Replace YOUR_SERVER_IP with the IP address of your server."
    echo "2. Use the password you just chose."
    echo
    echo "Testing commands:"
    echo "redis-cli -h YOUR_SERVER_IP -p 6379 -a $REDIS_PASS ping"
    echo
    echo "Expected output: PONG"
else
    echo "Redis failed to start after configuration changes."
    echo "Check 'systemctl status redis-server' and 'journalctl -xeu redis-server.service' for details."
fi