How to Create An Automatic Restart Script when Apache Web-server is Failed?

Website downtime is a significant concern for any online presence. A crashed web server translates directly to lost revenue and frustrated users. While Apache, a robust and widely-used web server, is generally reliable, unforeseen circumstances like memory leaks, sudden traffic surges, or configuration errors can cause it to fail. This guide provides a detailed, step-by-step approach to automating Apache restarts, minimizing downtime, and ensuring consistent web service availability. We will leverage systemd, the powerful service manager found in many Linux distributions, to build a robust and reliable solution.

Step 1: Configuring Apache for Automatic Restarts via Systemd

Systemd offers a built-in mechanism to automatically restart services upon failure. We'll modify Apache's systemd service file to incorporate this functionality. This initial step provides a primary layer of protection against unexpected crashes.

Begin by opening Apache's systemd service file using a text editor with root privileges:

      sudo nano /lib/systemd/system/apache2.service
    

Locate the [Service] section within this file. Add the following lines within this section:

Restart=on-failure
StartLimitBurst=5
StartLimitInterval=200
    

• Restart=on-failure: This directive instructs systemd to automatically restart the Apache service (apache2) if it unexpectedly terminates.

• StartLimitBurst=5: This parameter limits the number of automatic restart attempts to five. This prevents an infinite loop if Apache repeatedly crashes due to a persistent issue.

• StartLimitInterval=200: This sets a 200-second window for counting restart attempts. If Apache fails more than five times within this 200-second period, systemd will cease further restarts. This crucial safeguard avoids a runaway process that could overwhelm the system.

After adding these lines, save the file (Ctrl+X, then Y, then Enter). Then, reload systemd's configuration and restart Apache to apply the changes:

sudo systemctl daemon-reload
sudo systemctl restart apache2
    

sudo systemctl daemon-reload refreshes systemd's internal configuration, ensuring it recognizes the modifications made to the Apache service file. sudo systemctl restart apache2 restarts the Apache service, initiating the new automatic restart behavior.

Step 2: Implementing a Systemd Timer for Proactive Monitoring and Restarts

While the previous step enables automatic restarts upon failure, an additional layer of protection enhances reliability. This step creates a systemd timer that periodically checks Apache's status and restarts it if necessary, proactively preventing downtime even if the automatic restart mechanism misses a failure.

First, we create a shell script that checks Apache's status and performs a restart if needed:

      sudo nano /usr/local/bin/restart-apache.sh
    

Add the following script to the file:

#!/bin/bash
# Check if Apache2 is active
if ! systemctl is-active --quiet apache2; then
    # If not active, restart Apache2
    systemctl restart apache2
fi
    

This script uses systemctl is-active --quiet apache2 to silently check if Apache is running. If it's not active, systemctl restart apache2 is executed to restart the service. Save the file and make it executable:

      sudo chmod +x /usr/local/bin/restart-apache.sh
    

Next, create a systemd timer to run this script regularly:

      sudo nano /etc/systemd/system/restart-apache.timer
    

Add the following configuration to this file:

[Unit]
Description=Check and restart Apache if needed

[Timer]
OnBootSec=1min
OnUnitActiveSec=1min
Unit=restart-apache.service

[Install]
WantedBy=timers.target
    

• OnBootSec=1min: This ensures the check runs one minute after the system boots.

• OnUnitActiveSec=1min: This configures the timer to run the check every minute.

• Unit=restart-apache.service: This links the timer to the service we'll create next.

Now, create the corresponding systemd service file:

      sudo nano /etc/systemd/system/restart-apache.service
    

Add the following content:

[Unit]
Description=Restart Apache if it is not running

[Service]
Type=oneshot
ExecStart=/usr/local/bin/restart-apache.sh
    

This service defines a one-shot execution of the restart-apache.sh script whenever triggered by the timer. Finally, enable and start the timer:

sudo systemctl daemon-reload
sudo systemctl enable restart-apache.timer
sudo systemctl start restart-apache.timer
    

sudo systemctl daemon-reload ensures systemd loads the new timer definition. sudo systemctl enable restart-apache.timer enables the timer to start automatically on boot. sudo systemctl start restart-apache.timer initiates the timer immediately.

Step 3: Testing the Automated Restart Mechanism

To verify the setup, manually stop Apache and observe its automatic restart:

      sudo systemctl stop apache2
    

Wait for a minute or two, then check Apache's status:

      sudo systemctl status apache2
    

If configured correctly, Apache should have automatically restarted. You can also examine the systemd logs for any relevant messages indicating the automatic restarts.

Conclusion:

This comprehensive approach ensures high availability for your Apache web server. The combination of automatic restarts on failure and proactive monitoring via the systemd timer provides a robust solution for minimizing downtime and maintaining consistent web service availability. This is especially crucial for production environments where continuous uptime is paramount. This strategy minimizes manual intervention, ensuring a smoother, more reliable web service experience for your users.

Keywords: Apache, Web Server, Automatic Restart, Systemd, High Availability, Downtime Prevention, Linux, Web Server Monitoring, Server Maintenance