Redis Installation and Configuration Script.sh

#!/bin/bash

# Exit immediately if a command exits with a non-zero status
set -e

# Variables
REDIS_PASSWORD=$(openssl rand -base64 37 | cut -c1-49)
echo -e "Password: =>\033[1;32m$REDIS_PASSWORD\033[0m<="

REDIS_CONFIG_PATH="/etc/redis/redis.conf"
REDIS_LOG_PATH="/var/log/redis"
REDIS_DATA_PATH="/var/lib/redis"

# Function to check if Redis is already installed
check_redis_installed() {
  if command -v redis-server > /dev/null 2>&1; then
    echo "Redis is already installed."
    read -p "Do you want to reinstall Redis? (yes/no): " choice
    if [[ "$choice" != "yes" ]]; then
      echo "Skipping Redis installation."
      exit 0
    else
      echo "Reinstalling Redis..."
      sudo systemctl stop redis-server || true
      sudo apt-get remove --purge -y redis-server
      sudo rm -rf /var/lib/redis /etc/redis /var/log/redis
    fi
  fi
}

# Install Redis via APT
install_redis() {
  echo "Installing Redis from APT..."
  sudo apt update
  sudo apt install -y redis-server
}

# Set up directories and permissions
setup_directories() {
  echo "Setting up Redis directories..."
  
  # Ensure Redis user exists
  if ! id -u redis > /dev/null 2>&1; then
    echo "Redis user does not exist. Creating it..."
    sudo adduser --system --group --no-create-home redis
  fi
  
  # Create directories
  sudo mkdir -p $REDIS_LOG_PATH
  sudo mkdir -p $REDIS_DATA_PATH
  sudo chown redis:redis $REDIS_DATA_PATH
  sudo chmod 770 $REDIS_DATA_PATH
}

# Configure Redis as a systemd service
setup_systemd_service() {
  echo "Configuring Redis as a systemd service..."
  sudo cp /etc/redis/redis.conf /etc/redis/redis.conf.backup || true
  sudo tee /etc/systemd/system/redis-server.service > /dev/null <<EOL
[Unit]
Description=Redis In-Memory Data Store
After=network.target

[Service]
User=redis
Group=redis
ExecStart=/usr/bin/redis-server $REDIS_CONFIG_PATH
ExecStop=/usr/bin/redis-cli shutdown
Restart=always

[Install]
WantedBy=multi-user.target
EOL
  sudo systemctl daemon-reload
}

# Configure Redis security and settings
configure_redis() {
  echo "Configuring Redis security settings..."
  sudo tee $REDIS_CONFIG_PATH > /dev/null <<EOL
# Redis Configuration File
# Bind to all interfaces
bind 0.0.0.0
# Require password authentication
requirepass $REDIS_PASSWORD
# Protect against data loss: Append-only mode
appendonly yes
# Set maximum memory usage and eviction policy
maxmemory 512mb
maxmemory-policy allkeys-lru
# Disable dangerous commands
rename-command FLUSHALL ""
rename-command FLUSHDB ""
rename-command DEBUG ""
# Logging
logfile $REDIS_LOG_PATH/redis.log
# Set data directory
dir $REDIS_DATA_PATH
# Enable TCP Keepalive
tcp-keepalive 60
# Limit the number of client connections
maxclients 1000
# Protected mode
protected-mode yes
EOL

  # Set up permissions for Redis files
  sudo chown redis:redis $REDIS_CONFIG_PATH
  sudo chmod 640 $REDIS_CONFIG_PATH
  
  # Set up permissions for Redis log
  sudo touch $REDIS_LOG_PATH/redis.log
  sudo chown redis:redis $REDIS_LOG_PATH/redis.log
}

# Start Redis and enable the service
start_redis() {
  echo "Starting Redis server..."
  sudo systemctl enable redis-server
  sleep 5
  
  if ! sudo systemctl start redis-server; then
    echo "Failed to start Redis server. Check /var/log/redis/redis.log for errors."
    exit 1
  fi

  echo "Verifying Redis installation..."
  if systemctl status redis-server | grep -q "active (running)"; then
    echo "Redis is successfully installed and running!"
    echo "You can connect to the Redis server with the following details:"
    echo "Host: $(hostname -I | awk '{print $1}')"
    echo "Port: 6379"
    echo -e "Password: =>\033[1;32m$REDIS_PASSWORD\033[0m<="
    echo "Please save this password securely."
  else
    echo "Redis installation or startup failed. Check the logs for details."
    exit 1
  fi
}

# Main script execution
main() {
  check_redis_installed
  install_redis
  setup_directories
  setup_systemd_service
  configure_redis
  start_redis
}

# Execute the script
main