[Restart REDIS] Checks if REDIS is running and restarts if it isn't. #bash #REDIS #servers

restart-redis.sh

#!/bin/bash

# Script to monitor and manage a Redis server.
# This script checks if Redis is running, executes a FLUSHALL command if it's down,
# sends email notifications, and rotates log files based on a specified age.

# Required Software:
# - redis-cli: Command-line interface for Redis.
# - sendmail: For sending email notifications.
# - awk: For processing log files.
# Ensure these are installed and accessible on the server.

# Usage:
# - This script should be run by a user with sudo access to execute Redis commands.
# - Configure the script by setting the appropriate variables below.

# Cron Setup:
# To run this script periodically, add a cron job. For example, to run every hour:
# 0 * * * * /path/to/restart-redis.sh

# Configuration
REDIS_CLI="/usr/bin/redis-cli"      # Path to redis-cli
EMAIL="[email protected]"       # Recipient email address
SERVER="web1.example.com"  # Name of the server
FLUSH_COMMAND="FLUSHALL"
SENDER="[email protected]"     # Sender's email address
SEND_NOTIFICATION=true    # Boolean for sending notifications
LOG_FILE="/var/log/redis_check.log"   # Log file path
LOG_AGE=2  # Number of days to keep log entries
MEMORY_USAGE_THRESHOLD=75  # Percentage of maxmemory to trigger FLUSHALL

# Function to rotate logs
rotate_logs() {
    # Use awk to filter out log entries older than LOG_AGE days
    awk -v date="$(date --date="$LOG_AGE days ago" '+%Y-%m-%d')" '$1 >= date' $LOG_FILE > "${LOG_FILE}.tmp" && mv "${LOG_FILE}.tmp" $LOG_FILE
}

# Function to check memory usage
check_memory_usage() {
    local used_memory max_memory memory_usage_percentage
    used_memory=$($REDIS_CLI INFO memory | grep used_memory: | awk -F: '{print $2}')
    max_memory=$($REDIS_CLI INFO memory | grep maxmemory: | awk -F: '{print $2}')

    # If maxmemory is set to 0, it means no limit is set, so we skip the check
    if [ "$max_memory" -eq 0 ]; then
        echo "No maxmemory limit set. Skipping memory usage check."
        return 0
    fi

    # Calculate the percentage of used memory
    memory_usage_percentage=$((used_memory * 100 / max_memory))

    if [ "$memory_usage_percentage" -ge "$MEMORY_USAGE_THRESHOLD" ]; then
        echo "Memory usage is high: $memory_usage_percentage% of maxmemory. Running FLUSHALL command..."
        sudo $REDIS_CLI $FLUSH_COMMAND
        SUBJECT="REDIS Memory Cleared [$SERVER]"
        MESSAGE="Memory usage was high ($memory_usage_percentage% of maxmemory), and the FLUSHALL command has been executed on $(date '+%Y-%m-%d %H:%M:%S')."
        return 1
    fi
    return 0
}

# Check if Redis is running
if ! $REDIS_CLI PING | grep -q "PONG"; then
    echo "REDIS is down. Running FLUSHALL command..."
    sudo $REDIS_CLI $FLUSH_COMMAND
    SUBJECT="REDIS Restarted [$SERVER]"
    MESSAGE="REDIS was down, and the FLUSHALL command has been executed on $(date '+%Y-%m-%d %H:%M:%S')."
    if [ "$SEND_NOTIFICATION" = false ]; then
        SEND_NOTIFICATION=true # Ensure we send a notification when restarting REDIS
    fi
else
    # Check memory usage
    if ! check_memory_usage; then
        SEND_NOTIFICATION=true
    else
        SUBJECT="REDIS is Running [$SERVER]"
        MESSAGE="REDIS was found to be running on $(date '+%Y-%m-%d %H:%M:%S')."
        echo "Redis is running."
    fi
fi

if [ "$SEND_NOTIFICATION" = true ]; then
    {
        echo "Subject: $SUBJECT"
        echo "From: $SENDER"
        echo "To: $EMAIL"
        echo ""
        echo "$MESSAGE"
    } | /usr/sbin/sendmail -t
fi

# Rotate logs
rotate_logs

echo "$(date '+%Y-%m-%d %H:%M:%S') - Redis check executed." >> $LOG_FILE