Introduction

Let’s Encrypt is a Certificate Authority (CA) that facilitates obtaining and installing free TLS/SSL certificates, thereby enabling encrypted HTTPS on web servers. It streamlines the process by providing a software client, Certbot, that attempts to automate most (if not all) of the required steps. Currently, the entire process of obtaining and installing a certificate is fully automated on both Apache and Nginx.

In this guide, you’ll use Certbot to obtain a free SSL certificate for Apache on Ubuntu and make sure this certificate is set up to renew automatically.

This tutorial uses a separate virtual host file instead of Apache’s default configuration file for setting up the website that will be secured by Let’s Encrypt. We recommend creating new Apache virtual host files for each domain hosted in a server because it helps to avoid common mistakes and maintains the default configuration files as a fallback setup.

How To Secure Apache with Let’s Encrypt on Ubuntu

1. Installing Certbot
2. Checking your Apache Virtual Host Configuration
3. Allowing HTTPS Through the Firewall
4. Obtaining an SSL Certificate
5. Verifying Certbot Auto-Renewal

Prerequisites

To follow this tutorial, you will need:

• One Ubuntu server set up with a non-root user with sudo administrative privileges and firewall enabled. You can set this up by following our initial server setup for Ubuntu tutorial.
• A fully registered domain name. This tutorial will use your_domain as an example throughout. You can purchase a domain name on Namecheap, get one for free on Freenom, or use the domain registrar of your choice.
• Both of the following DNS records set up for your server. You can follow this introduction to DigitalOcean DNS for details on how to add them.
  • An A record with your_domain pointing to your server’s public IP address.
  • An A record with www.your_domain pointing to your server’s public IP address.
• Apache installed by following How To Install Apache on Ubuntu. Be sure that you have a virtual host file for your domain. This tutorial will use /etc/apache2/sites-available/your_domain.conf as an example.

Step 1 — Installing Certbot

To obtain an SSL certificate with Let’s Encrypt, you need to install the Certbot software on your server. You’ll use the default Ubuntu package repositories for that.

First, update the local package index:

You need two packages: certbot, and python3-certbot-apache. The latter is a plugin that integrates Certbot with Apache, making it possible to automate obtaining a certificate and configuring HTTPS within your web server with a single command:

You will be prompted to confirm the installation by pressing Y, then ENTER.

Certbot is now installed on your server. In the next step, you’ll verify Apache’s configuration to make sure your virtual host is set appropriately. This will ensure that the certbot client script will be able to detect your domains and reconfigure your web server to use your newly generated SSL certificate automatically.

Step 2 — Checking your Apache Virtual Host Configuration

To automatically obtain and configure SSL for your web server, Certbot needs to find the correct virtual host within your Apache configuration files. Your server domain name(s) will be retrieved from the ServerName and ServerAlias directives defined within your VirtualHost configuration block.

If you followed the virtual host setup step in the Apache installation tutorial, you should have a VirtualHost block set up for your domain at /etc/apache2/sites-available/your_domain.conf with the ServerName and also the ServerAlias directives already set appropriately.

To confirm this is set up, open the virtual host file for your domain using nano or your preferred text editor:

Find the existing ServerName and ServerAlias lines. They should be listed as follows:

...
ServerName your_domain
ServerAlias www.your_domain
...

If you already have your ServerName and ServerAlias set up like this, you can exit your text editor and move on to the next step. If your current virtual host configuration doesn’t match the example, update it accordingly. If you’re using nano, you can exit by pressing CTRL+X, then Y and ENTER to confirm your changes, if any. Then, run the following command to validate your changes:

You should receive Syntax OK as a response. If you get an error, reopen the virtual host file and check for any typos or missing characters. Once your configuration file’s syntax is correct, reload Apache so that the changes take effect:

With these changes, Certbot will be able to find the correct VirtualHost block and update it.

Next, you’ll update the firewall to allow HTTPS traffic.

Step 3 — Allowing HTTPS Through the Firewall

If you have the UFW firewall enabled, as recommended by the prerequisite guides, you’ll need to adjust the settings to allow HTTPS traffic. Upon installation, Apache registers a few different UFW application profiles. You can leverage the Apache Full profile to allow both HTTP and HTTPS traffic on your server.

To verify what kind of traffic is currently allowed on your server, check the status:

If you followed one of our Apache installation guides, you will have output similar to the following, meaning that only HTTP traffic on port 80 is currently allowed:

Status: active

To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere                  
Apache                     ALLOW       Anywhere             
OpenSSH (v6)               ALLOW       Anywhere (v6)             
Apache (v6)                ALLOW       Anywhere (v6)

To allow for HTTPS traffic, allow the “Apache Full” profile:

Then delete the redundant “Apache” profile:

Your status will display as the following:

Status: active

To                         Action      From
--                         ------      ----
OpenSSH                    ALLOW       Anywhere                  
Apache Full                ALLOW       Anywhere                  
OpenSSH (v6)               ALLOW       Anywhere (v6)             
Apache Full (v6)           ALLOW       Anywhere (v6)        

You are now ready to run Certbot and obtain your certificates.

Step 4 — Obtaining an SSL Certificate

Certbot provides a variety of ways to obtain SSL certificates through plugins. The Apache plugin will take care of reconfiguring Apache and reloading the configuration whenever necessary. To use this plugin, run the following:

This script will prompt you to answer a series of questions in order to configure your SSL certificate. First, it will ask you for a valid email address. This email will be used for renewal notifications and security notices:

Saving debug log to /var/log/letsencrypt/letsencrypt.log
Enter email address (used for urgent renewal and security notices)
 (Enter 'c' to cancel): you@your_domain

After providing a valid email address, press ENTER to proceed to the next step. You will then be prompted to confirm if you agree to Let’s Encrypt terms of service. You can confirm by pressing Y and then ENTER:

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Please read the Terms of Service at
https://letsencrypt.org/documents/LE-SA-v1.2-November-15-2017.pdf. You must
agree in order to register with the ACME server at
https://acme-v02.api.letsencrypt.org/directory
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
(Y)es/(N)o: Y

Next, you’ll be asked if you would like to share your email with the Electronic Frontier Foundation to receive news and other information. If you do not want to subscribe to their content, write N. Otherwise, write Y then press ENTER to proceed to the next step:

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Would you be willing to share your email address with the Electronic Frontier
Foundation, a founding partner of the Let's Encrypt project and the non-profit
organization that develops Certbot? We'd like to send you email about our work
encrypting the web, EFF news, campaigns, and ways to support digital freedom.
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(Y)es/(N)o: N

The next step will prompt you to inform Certbot of which domains you’d like to activate HTTPS for. The listed domain names are automatically obtained from your Apache virtual host configuration, so it’s important to make sure you have the correct ServerName and ServerAlias settings configured in your virtual host. If you’d like to enable HTTPS for all listed domain names (recommended), you can leave the prompt blank and press ENTER to proceed. Otherwise, select the domains you want to enable HTTPS for by listing each appropriate number, separated by commas and/ or spaces, then press ENTER:

Which names would you like to activate HTTPS for?
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1: your_domain
2: www.your_domain
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Select the appropriate numbers separated by commas and/or spaces, or leave input
blank to select all options shown (Enter 'c' to cancel): 

After this step, Certbot’s configuration is finished, and you will be presented with the final remarks about your new certificate and where to locate the generated files:

Successfully received certificate.
Certificate is saved at: /etc/letsencrypt/live/your_domain/fullchain.pem
Key is saved at:         /etc/letsencrypt/live/your_domain/privkey.pem
This certificate expires on 2022-07-10.
These files will be updated when the certificate renews.
Certbot has set up a scheduled task to automatically renew this certificate in the background.

Deploying certificate
Successfully deployed certificate for your_domain to /etc/apache2/sites-available/your_domain-le-ssl.conf
Successfully deployed certificate for www.your_domain.com to /etc/apache2/sites-available/your_domain-le-ssl.conf
Congratulations! You have successfully enabled HTTPS on https:/your_domain and https://www.your_domain.com

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If you like Certbot, please consider supporting our work by:
 * Donating to ISRG / Let's Encrypt:   https://letsencrypt.org/donate
 * Donating to EFF:                    https://eff.org/donate-le
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Your certificate is now installed and loaded into Apache’s configuration. Try reloading your website using https:// and notice your browser’s security indicator. It should indicate that your site is properly secured, typically by a lock icon in the address bar.

You can use the SSL Labs Server Test to verify your certificate’s grade and obtain detailed information about it, from the perspective of an external service.

In the next and final step, you’ll test the auto-renewal feature of Certbot, which guarantees that your certificate will be renewed automatically before the expiration date.

Step 5 — Verifying Certbot Auto-Renewal

Let’s Encrypt’s certificates are only valid for ninety days. This is to encourage users to automate their certificate renewal process, as well as to ensure that misused certificates or stolen keys will expire sooner rather than later.

The certbot package you installed takes care of renewals by including a renew script to /etc/cron.d, which is managed by a systemctl service called certbot.timer. This script runs twice a day and will automatically renew any certificate that’s within thirty days of expiration.

To check the status of this service and make sure it’s active, run the following:

Your output will be similar to the following:

● certbot.timer - Run certbot twice daily
     Loaded: loaded (/lib/systemd/system/certbot.timer; enabled; vendor preset:>
     Active: active (waiting) since Mon 2022-04-11 20:52:46 UTC; 4min 3s ago
    Trigger: Tue 2022-04-12 00:56:55 UTC; 4h 0min left
   Triggers: ● certbot.service

Apr 11 20:52:46 jammy-encrypt systemd[1]: Started Run certbot twice daily.

To test the renewal process, you can do a dry run with certbot:

Saving debug log to /var/log/letsencrypt/letsencrypt.log

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Processing /etc/letsencrypt/renewal/your_domain.conf
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Account registered.
Simulating renewal of an existing certificate for your_domain and www.your_domain.com

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Congratulations, all simulated renewals succeeded:
  /etc/letsencrypt/live/your_domain/fullchain.pem (success)
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If you don’t receive any errors, you’re all set. When necessary, Certbot will renew your certificates and reload Apache to pick up the changes. If the automated renewal process ever fails, Let’s Encrypt will send a message to the email you specified, warning you when your certificate is about to expire.

Conclusion

In this tutorial, you installed the Let’s Encrypt client certbot, configured and installed an SSL certificate for your domain, and confirmed that Certbot’s automatic renewal service is active within systemctl. If you have further questions about using Certbot, their documentation is a good place to start.

High availability is crucial for critical systems that should remain accessible even in the face of hardware or software failures. Pacemaker and Corosync are open-source tools that allow you to create a high-availability cluster on your Ubuntu servers. In this tutorial, I will guide you through the process of setting up a high-availability cluster using Pacemaker and Corosync on Ubuntu, ensuring that your services remain available with minimal downtime.

Section 1: Understanding High Availability Clustering

Before diving into the configuration, let’s briefly understand what high availability clustering is:

High availability clustering involves grouping multiple servers (nodes) together to provide redundancy for critical services. If one node fails, another takes over seamlessly, ensuring continuous service availability.

Section 2: Setting Up Pacemaker and Corosync

Step 1: Install Pacemaker and Corosync On each node, install the Pacemaker and Corosync packages:

sudo apt update
sudo apt install pacemaker corosync

Step 2: Configure Corosync Edit the Corosync configuration file on each node:

sudo nano /etc/corosync/corosync.conf

Here’s a basic configuration example for a two-node cluster:

totem {
    version: 2
    secauth: off
    cluster_name: my_cluster
    transport: udpu
}

nodelist {
    node {
        ring0_addr: node1_IP
        nodeid: 1
    }
    node {
        ring0_addr: node2_IP
        nodeid: 2
    }
}
quorum {
    provider: corosync_votequorum
}

Replace node1_IP and node2_IP with the actual IP addresses of your nodes.

Step 3: Start Corosync Start the Corosync service on each node:

sudo systemctl start corosync

Step 4: Enable Corosync at Boot Ensure Corosync starts automatically at boot:

sudo systemctl enable corosync

Section 3: Configuring Pacemaker

Step 5: Start Pacemaker Start the Pacemaker service on each node:

sudo systemctl start pacemaker

Step 6: Enable Pacemaker at Boot Enable Pacemaker to start automatically at boot:

sudo systemctl enable pacemaker

Section 4: Creating a Resource

Step 7: Create a Resource Agent Pacemaker manages resources using resource agents. To create a simple resource agent for a virtual IP (VIP) address, create a file like vip.sh:

sudo nano /usr/local/bin/vip.sh

Add the following content and make the script executable:

#!/bin/bash
/sbin/ifconfig eth0:0 $1 netmask 255.255.255.0 up

sudo chmod +x /usr/local/bin/vip.sh

Step 8: Create a Resource Now, create a Pacemaker resource for the VIP. On one of the nodes, run:

sudo crm configure primitive vip ocf:heartbeat:IPaddr2 params ip="VIP_IP" nic="eth0" cidr_netmask="24" op monitor interval="10s"

Replace VIP_IP with the virtual IP address you want to use.

Step 9: Create a Resource Group Create a resource group that includes the VIP resource:

sudo crm configure group vip_group vip

Section 5: Testing Failover

Step 10: Simulate Node Failure To test the cluster, simulate a node failure by stopping the Corosync service on one of the nodes:

sudo systemctl stop corosync

Check the status of the cluster on the remaining node:

sudo crm status

You should see that the VIP has moved to the surviving node.

Section 6: Additional Configuration

To configure more resources, fencing, or complex constraints, refer to the Pacemaker documentation and tutorials. Pacemaker and Corosync offer a wide range of features for building highly available systems.

WooHoo! You’ve successfully set up a high-availability cluster on Ubuntu using Pacemaker and Corosync. Your services are now resilient to node failures, providing uninterrupted availability for critical applications.

I hope you have found this article useful. If so, please consider following me here and on social media. Also, if you need 24 x 7 linux help, check out my company: https://techguys2go.com

Cheers!

apt update -y
apt upgrade -y

reboot

apt install apache2 -y

systemctl start apache2
systemctl enable apache2

systemctl status apache2

nano /var/www/html/web1.html

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

    <title>Apache Web Server1</title>

<h2>This is Apache Web Server 1 Page!</h2>

</html>

nano /etc/apache2/sites-enabled/web1.conf

<VirtualHost *:80>
        ServerName web1.example.com
        ServerAdmin webmaster@localhost
        DocumentRoot /var/www/html
        DirectoryIndex web1.html
        ErrorLog ${APACHE_LOG_DIR}/error.log
        CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>

systemctl restart apache2

nano /var/www/html/web2.html

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

    <title>Apache Web Server2</title>

<h2>This is Apache Web Server 2 Page!</h2>

</html>

nano /etc/apache2/sites-enabled/web2.conf

<VirtualHost *:80>
        ServerName web2.example.com
        ServerAdmin webmaster@localhost
        DocumentRoot /var/www/html
        DirectoryIndex web2.html
        ErrorLog ${APACHE_LOG_DIR}/error.log
        CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>

systemctl restart apache2

a2enmod proxy
a2enmod proxy_http
a2enmod proxy_balancer
a2enmod lbmethod_byrequests

systemctl restart apache2

apachectl -M | grep proxy

nano /etc/apache2/sites-enabled/loadbalancer.conf

<VirtualHost *:80>
      ServerName balancer.example.com
     <Proxy balancer://webserver>
       BalancerMember http://web1.example.com
       BalancerMember http://web2.example.com
       ProxySet stickysession=ROUTEID

      </Proxy>
      ProxyPreserveHost On
      ProxyPass / balancer://webserver/
      ProxyPassReverse / balancer://webserver/
</VirtualHost>

systemctl restart apache2

When you have a load balancer, a common challenge comes in achieving availability, especially where continuous service availability is required. Even a load balancer can fail you if you have not incorporated a way to ensure its availability, and that’s where Keepalived comes into play.
It is an open-source framework that is designed for Linux systems to achieve reliability by managing the load balancing and IP failover. Keepalived is used with a load balancer such as HAProxy to ensure the continuity of service to achieve reliability. This post introduces Keepalived and goes through the steps to set it up with HAProxy.

What Is Keepalived?

A load balancer, such as HAProxy, is handy in handling the traffic to your site. However, you may get a case where availability is not guaranteed. Keepalived is an open-source software that ensures high availability by managing the IP failover with your load balancer and works seamlessly with HAProxy.

Some of the key features provided by Keepalived include the following:

1. Virtual IP Management

All servers are assigned with a virtual IP by Keepalived which allows them to operate as one virtual entity. Keepalived transfers the virtual IP to a backup server in case of a failover, avoiding downtime.

2. Health Checking

Keepalived is designed in a way that it can check the health of all services it manages. For instance, if a server is unresponsive, it immediately starts a failover and finds a backup server. With this health checking and failover feature, availability is guaranteed.

3. Load Balancing

Although its primary purpose is not being a load balancer, it’s possible to configure it to distribute the incoming traffic to different servers. This functionality is combined with a load balancer to enhance the system performance.

How to Set Up HAProxy with Keepalived

We already mentioned that Keepalived works with a load balancer. For this case, we set up HAProxy with Keepalived for high availability. Therefore, we must first install HAProxy and then set it up. Follow the given steps:

Step 1: Install HAProxy

Installing HAProxy is a straightforward process, especially since HAProxy is available from the default Linux repository. We are working with Ubuntu for this tutorial, but the steps are similar to those of the other distros.

Before installing HAProxy, quickly update the repository.

$ sudo apt update

You can now use APT to install HAProxy.

$ sudo apt-get install haproxy

Step 2: Configure HAProxy

On your HAProxy, we must access the configuration file, define how you want to receive the incoming traffic from your client devices, and then define which servers to distribute the traffic.

Start by accessing the HAProxy config file.

$ sudo nano /etc/haproxy/haproxy.cfg

For this case, we specify that we will listen for all incoming connections via port 80. For the backend, we specify two servers using round robin to distribute the traffic. Ensure that you replace the server IPs to match your actual servers.

After you make the required edits to the config file, save it and exit. Lastly, restart HAProxy.

Step 3: Install Keepalived

Keepalived doesn’t come preinstalled in Linux. As such, we must install it from the default repository using APT. Run the following command:

$ sudo apt-get install keepalived

Confirm the installation by pressing “y” when prompted. Once the installation is complete, verify that Keepalived has been installed by checking its version.

Step 4: Configure Keepalived

To configure Keepalived, we must access its configuration file which is located at “/etc/keepalived/keepalived.conf”. Here, we must define how we want Keepalived to offer high availability to HAProxy.

We must define the virtual IP address, the priority for the available servers, and the script to check the health and status of HAProxy. In the following configuration file, we create the “chk_haproxy” script to asses HAProxy’s status every two seconds. We specify it using “enp0s3” as our network interface and create a VRRP instance named “VI_1”. Change the network interface to match your case.

Still, set a router ID that works for your interface and set what virtual IP address to use. You should also change the authentication password.

Step 5: Restart Keepalived

Once your Keepalived configuration is all set, save the file and close the text editor. You can then check the validity of the configuration file and restart the Keepalived service.

Lastly, ensure that HAProxy and Keepalived are started.

That’s it. You set up HAProxy with Keepalived for high availability. You can use the defined virtual IP to verify that the setup works as expected.

Conclusion

The setup that is defined in this post ensures that your load balancer is highly available to handle the incoming traffic by distributing it to the available servers. Moreover, Keepalived ensures that it handles failover and you won’t have cases of downtime with your load balancer. Follow through the steps and edit the configuration file to suit your preference.