Alright, guys, let's dive straight into getting HAProxy 2.7 up and running on your CentOS 7 server. This guide is designed to be super straightforward, so even if you're not a Linux guru, you should be able to follow along without any hiccups. HAProxy is an amazing load balancer, and version 2.7 brings some cool improvements, making it well worth the upgrade or fresh install. We'll walk through each step, ensuring you have a robust and reliable setup. So, buckle up, and let's get started!

Prerequisites

Before we get our hands dirty with the installation, let's make sure we've got all our ducks in a row. These prerequisites are crucial for a smooth and successful setup. Ignoring these might lead to some frustrating errors down the line, so pay close attention, alright?

1. A CentOS 7 Server

Obviously, you'll need a CentOS 7 server. It can be a physical machine, a virtual machine, or even a cloud instance. Ensure you have SSH access to it with a user that has sudo privileges. If you're setting up a cloud instance, most providers offer CentOS 7 as a standard image. Just spin one up, and you're good to go. For local VMs, tools like VirtualBox or VMware work perfectly. Make sure your server is reachable and has internet access to download packages. This is the most important and first step. Don't forget!

2. Basic System Updates

It's always a good idea to start with a clean slate. Update your system to the latest packages to avoid any compatibility issues. Open your terminal and run these commands:

sudo yum update -y
sudo yum upgrade -y

These commands will update all installed packages to their newest versions. The -y flag automatically answers "yes" to any prompts, so you don't have to sit there and click through each update. Keeping your system updated ensures you have the latest security patches and bug fixes, which is super important for the overall health of your server. After the update, a reboot might be a good idea to ensure all changes are applied.

3. Install Required Packages

We'll need a few extra packages to build HAProxy from source. These include development tools and libraries. Install them using the following command:

sudo yum install -y gcc pcre-devel zlib-devel openssl-devel tar wget

Let's break this down:

• gcc: The GNU Compiler Collection, essential for compiling C source code.
• pcre-devel: Perl Compatible Regular Expressions development files, needed for HAProxy's advanced pattern matching.
• zlib-devel: Compression library development files, used for compressing HTTP traffic.
• openssl-devel: OpenSSL development files, required for SSL/TLS encryption.
• tar: Used for extracting the HAProxy source code from the tarball.
• wget: Used for downloading the HAProxy source code.

Installing these packages ensures that you have all the necessary tools and libraries to compile HAProxy without any missing dependencies. This step is crucial, so double-check that all packages are installed correctly.

Downloading HAProxy 2.7

Now that we've got our server prepped and ready, let's snag the HAProxy 2.7 source code. We'll download it directly from the HAProxy website using wget. This ensures we get the latest and greatest version. Make sure to check the HAProxy website for the most up-to-date download link, as versions change frequently. We want to download the latest and stable version for production.

1. Download the Source Code

First, navigate to your home directory or a directory where you want to store the downloaded file. Then, use wget to download the source code. As an example, let's assume the latest version is 2.7.4. You can find the correct link on the official HAProxy website. Here's how you'd download it:

cd /usr/local/src
sudo wget [https://www.haproxy.org/download/2.7/src/haproxy-2.7.4.tar.gz](https://www.haproxy.org/download/2.7/src/haproxy-2.7.4.tar.gz)

Note: Always replace the link with the actual link to the latest version from the HAProxy website.

2. Extract the Source Code

Once the download is complete, extract the source code using the tar command:

sudo tar -xzf haproxy-2.7.4.tar.gz
cd haproxy-2.7.4

This command will extract the contents of the tarball into a new directory named haproxy-2.7.4. The -x flag tells tar to extract, -z tells it to decompress gzip, and -f specifies the file to extract. After extraction, we change our directory into the newly created HAProxy directory.

Compiling and Installing HAProxy

With the source code downloaded and extracted, the next step is to compile and install HAProxy. This involves configuring the build, compiling the code, and installing the binaries. It sounds complex, but we'll break it down into simple steps.

1. Configure the Build

Before compiling, we need to configure the build environment. This tells the compiler how to build HAProxy for our specific system. Use the make command with the appropriate options. For CentOS 7, this usually works well:

sudo make TARGET=linux-glibc USE_PCRE=1 USE_OPENSSL=1 USE_ZLIB=1

Let's break down these options:

• TARGET=linux-glibc: Specifies the target operating system. linux-glibc is the standard for most Linux distributions.
• USE_PCRE=1: Enables support for Perl Compatible Regular Expressions. This is essential for advanced pattern matching in HAProxy.
• USE_OPENSSL=1: Enables support for SSL/TLS encryption. This is crucial for securing your traffic.
• USE_ZLIB=1: Enables support for compression. This can improve performance by reducing the amount of data transferred.

This command configures the build process with the necessary options for a CentOS 7 system with SSL, PCRE, and Zlib support.

2. Compile HAProxy

Now that we've configured the build, let's compile the source code. This is where the magic happens. Simply run the make command:

sudo make

This command will compile the HAProxy source code into executable binaries. It might take a few minutes, depending on your server's resources. Watch the output for any errors. If you encounter any, double-check that you have all the required packages installed and that the build configuration is correct.

3. Install HAProxy

After successful compilation, install HAProxy using the make install command:

sudo make install

This command installs the HAProxy binaries to the appropriate system directories. By default, it installs the haproxy executable to /usr/local/sbin/. It also installs the documentation and configuration files. After this step, HAProxy should be installed on your system.

Configuring HAProxy

Now that HAProxy is installed, we need to configure it to do what we want. This involves creating a configuration file that defines how HAProxy should handle traffic. The configuration file is usually located at /usr/local/etc/haproxy/haproxy.cfg, but since it doesn't exist by default, we'll need to create it.

1. Create the Configuration File

Create the directory for HAProxy's configuration files:

sudo mkdir -p /usr/local/etc/haproxy

Now, create the haproxy.cfg file using your favorite text editor. For example, using nano:

sudo nano /usr/local/etc/haproxy/haproxy.cfg

2. Basic Configuration

Here's a basic configuration file to get you started. This configuration sets up a simple HTTP load balancer that forwards traffic to two backend servers:

global
    log /dev/log    local0
    log /dev/log    local1 notice
    chroot /var/lib/haproxy
    stats socket /run/haproxy/admin.sock mode 660 level admin
    stats timeout 30s
    user haproxy
    group haproxy
    daemon

defaults
    log     global
    mode    http
    option  httplog
    option  dontlognull
        timeout connect 5000
        timeout client  50000
        timeout server  50000
    errorfile 400 /etc/haproxy/errors/400.http
    errorfile 403 /etc/haproxy/errors/403.http
    errorfile 408 /etc/haproxy/errors/408.http
    errorfile 500 /etc/haproxy/errors/500.http
    errorfile 502 /etc/haproxy/errors/502.http
    errorfile 503 /etc/haproxy/errors/503.http
    errorfile 504 /etc/haproxy/errors/504.http

frontend main
    bind *:80
    default_backend webservers

backend webservers
    balance roundrobin
    server web1 192.168.1.101:80 check
    server web2 192.168.1.102:80 check

Let's break this down:

• global: Global settings for HAProxy, such as logging and user/group.
• defaults: Default settings for the frontend and backend.
• frontend main: Defines the frontend, which listens on port 80 and forwards traffic to the webservers backend.
• backend webservers: Defines the backend servers, which are two web servers with IP addresses 192.168.1.101 and 192.168.1.102. The balance roundrobin setting means that HAProxy will distribute traffic evenly between the servers.

3. Create HAProxy User

Create the haproxy user and group that we specified in the configuration file:

sudo groupadd haproxy
sudo useradd -g haproxy haproxy

4. Create the HAProxy Service

To manage HAProxy as a service, we need to create a systemd unit file. Create a file named haproxy.service in /etc/systemd/system/:

sudo nano /etc/systemd/system/haproxy.service

Add the following content to the file:

[Unit]
Description=HAProxy Load Balancer
After=network.target

[Service]
ExecStart=/usr/local/sbin/haproxy -f /usr/local/etc/haproxy/haproxy.cfg
ExecReload=/usr/local/sbin/haproxy -f /usr/local/etc/haproxy/haproxy.cfg -p /run/haproxy.pid -sf $(cat /run/haproxy.pid)
KillMode=mixed
PIDFile=/run/haproxy.pid
User=haproxy
Group=haproxy

[Install]
WantedBy=multi-user.target

This unit file tells systemd how to start, stop, and restart HAProxy. It also specifies the user and group that HAProxy should run as.

Starting and Managing HAProxy

With the configuration file and service unit in place, we can now start and manage HAProxy using systemctl.

1. Start HAProxy

Enable and start the HAProxy service:

sudo systemctl enable haproxy
sudo systemctl start haproxy

The enable command ensures that HAProxy starts automatically on boot. The start command starts the service immediately.

2. Check the Status

Check the status of the HAProxy service to ensure it's running correctly:

sudo systemctl status haproxy

This command will show you the status of the HAProxy service, including whether it's active, any recent logs, and any errors. If the service is running correctly, you should see a message indicating that it's active and running.

3. Restart and Reload

To restart HAProxy:

sudo systemctl restart haproxy

To reload HAProxy (which applies configuration changes without dropping connections):

sudo systemctl reload haproxy

4. Verify HAProxy

To verify that HAProxy is working correctly, you can check the logs or access your website through the HAProxy load balancer. If everything is configured correctly, HAProxy should forward traffic to your backend servers.

You can also use curl to check the response from the load balancer:

curl http://your_server_ip

This should return the content from one of your backend servers, indicating that HAProxy is successfully load balancing traffic.

Conclusion

And there you have it! You've successfully installed and configured HAProxy 2.7 on CentOS 7. This setup provides a basic HTTP load balancer that distributes traffic between two backend servers. From here, you can customize the configuration to suit your specific needs, such as adding more backend servers, configuring SSL/TLS encryption, and setting up advanced routing rules. Remember to always test your configuration changes thoroughly before deploying them to a production environment.

HAProxy is a powerful and flexible load balancer, and with this guide, you're well on your way to mastering it. Happy load balancing, folks!