What Is HAProxy? How HAProxy Powers High-Performance Websites

Let me tell you, running a website, especially the back end, isn’t as easy as it may seem. One mistake could leave you counting losses or even hiring a reputation management agency to save your brand.

If you don’t believe me, go read the story of Lowe’s Black Friday crash in 2018. It’s the perfect example of how high-performance websites can crash at a time when you need them up and running the most. I can’t help but think about how things would’ve been different had they used a load balancer like HAProxy. If they did, they probably didn’t configure it correctly.

HAProxy is short for High Availability Proxy, a software that manages incoming traffic so no server gets overwhelmed.

Think of it as the friend at a party who calmly assigns tasks when you’re having anxiety attacks. “You handle snacks, I’ll take the drinks, and Sarah will greet people at the door. Let’s go!”

Without HAProxy, your website can get overwhelmed the moment too many users show up. And people get frustrated when that happens. Like, what do you mean you’re a coffee shop without lattes on a Monday morning? How’s that even possible? Mondays? Of all days of the week? Unbelievable.

HAProxy’s main job is to distribute traffic across a network of servers. But why shouldn’t servers take in the traffic all at once?

Here’s what you probably don’t know: servers are like humans. Sometimes, their plates get full. And when they do, they just can’t pile it on anymore.

HAProxy looks at the incoming traffic and says, “Server A looks pretty idle to me, I’ll let it handle X amount of traffic.” It then realizes there’s still more traffic coming in and goes, “Server B looks busy, but not that busy. I’m sure it can handle this batch.”

Another wave of traffic comes in, and the proxy faces another decision to make. So it takes a look around and identifies another server. Let’s call that Server C. It says, “Server C is probably the best for this role, but it’s been looking sickly lately, so I’ll not assign it any traffic until it fully recovers. I’ll let Server D take care of things.”

My main point here is that HAProxy really understands the servers it manages and decides how much traffic they can handle at any given time. The benefit? You won’t even notice when a server is down.

Importance of Load Balancing

Load balancing is one of the primary reasons websites stay up and running when there’s heavy traffic blowing in their direction.

Take Amazon.com, for example. On any given day, the eCommerce giant receives more than 300 million visits. Now, you can imagine the amount of traffic it receives on Black Friday or Cyber Monday.

Without load balancing, Amazon.com wouldn’t be able to handle such traffic. Servers wouldn’t even get a chance to react to what hit them. They’d be buried under an avalanche of traffic and never get a chance to breathe fresh air again. That brings me to my next point.

Role of HAProxy in Efficient Server Management

To the outside world, servers might look like they’ve got their lives together, but that’s too far from the truth. They still need someone to micromanage them. That’s where HAProxy steps in.

It knows that servers are not built the same. Nine times out of ten, server resources are not distributed evenly, either.

HAProxy steps in to make sure there’s a sense of balance. The last thing it wants is a server struggling to sustain high traffic when another server sits idly, snoozing from a distance.

And it’s not just about distributing traffic aimlessly. Rather, it’s about going down to the specifics. For example, “This amount of memory will handle this amount of traffic. This amount of storage space will handle this amount of data.”

Let’s now step outside the umbrella of traffic management and give HAProxy its flowers where it rightfully deserves.

• Open Source and Free: You don’t need a license to use this software. And because it’s free, it boasts quite a huge community of users.
• Flexibility and Customizability: Since servers are not designed the same, it makes sense that HAProxy is able to adapt to different environments. It can live on-premise, in the cloud, or even in a hybrid environment. The multiple HAProxy configurations also give it freedom and flexibility to exist wherever it wants.
• Scalability: Ever heard of the word scalability in web hosting? That wouldn’t even be a thing without a load balancer like HAProxy. In other words, servers wouldn’t be able to scale. And as a result, they’d quickly bow to the pressure of high traffic.
• Stability and Reliability: This is what you get when you meticulously distribute traffic across different servers. Because of this trait, HAProxy is commonly used in production environments (the live version of a website or application).

Note that these are just the primary benefits, not everything this software has to offer.

HAProxy isn’t just for load balancing. You’ll learn this by looking at its key features.

Load-balancing Algorithms

Load balancing is what HAProxy is best known for. But have you ever paused for a moment to think of what this process actually involves? If you didn’t know, algorithms play a massive role here.

These are the most popular algorithms:

• Round-robin: Round-robin algorithms, for example, distribute traffic across servers in turns. It’s like dishing out cards to players at a round table.
• Weighted round-robin: Then there’s the Weighted Round-robin. It assigns traffic based on strength but prefers to call it “weight.” The strongest server carries the heaviest load. Sounds fair, doesn’t it?
• Least connection: The Least Connection algorithm assigns traffic to the server with the fewest connections.
• Source-based algorithm: Finally, the Source-based algorithm keeps users on the same server throughout their visit. For example, when you’re watching a movie on Netflix, this algorithm makes sure that you stay connected to the same server. That way, your Netflix and Chill sessions remain uninterrupted.

Load-balancing algorithms can be classified as either static or dynamic. For example, round-robin is static, and least connection is dynamic.

SSL Termination

You can think of encrypted traffic (SSL/TLS) as something like carrying a heavy backpack. That heaviness comes from the added layer of security. Since it’s heavy, it can slow down servers.

HAProxy stands at the door and conducts an exercise called SSL termination. This is basically its way of decrypting traffic so that the servers in the backend won’t have to bear the heavy load.

The conversation at the entry point goes on like this:

“Hey, you can get in, but you’ll leave your backpack here with me.”

So what happens when the server responds to the decrypted data? In that case, it still has to go through our guy at the door (HAProxy) on its way out.

And before the response data leaves the server, HAProxy re-encrypts it. That way, the server gets to handle a lighter load while the user benefits from a secure data transfer process.

Health Checks

HAProxy also knows a thing or two about health and wellness, but for servers. If it finds that one has gone down or become too slow, it reroutes traffic to a healthier one. Interestingly, HAProxy conducts health checks in an organized manner.

The active health check is the first option. Here, it sends signals to test if servers are responsive. It’s like doing a wellness check on your neighbor after not hearing from them for quite a while.

The second option is the passive health check. It involves watching ongoing traffic for signs of trouble. Both of these strategies help prevent downtime.

High Availability (HA)

In tech lingo, high availability means staying online no matter what. But this doesn’t necessarily mean that servers can’t fail. They actually do fail more times than you can imagine.

Rather, it’s about having a rapid response to such failures. That’s where HAProxy walks in with a backup server ready to jump into action if something goes wrong. We call this rapid response a failover system because it makes sure there’s not even a single point of failure.

HTTP/2 and TCP Support

HTTP traffic is the data exchanged when you browse websites. I’m talking about simple stuff like loading web pages, watching videos, or even clicking links. It follows the Hypertext Transfer Protocol (HTTP), a method of communication between your browser and web servers.

On the other hand, TCP means Transmission Control Protocol.

TCP is the low-level data exchange used by various applications, like email, streaming, or databases.

TCP’s job is to make sure that data packets are sent, received, and reassembled correctly. It’s also responsible for making sure that nothing gets lost along the way during the process.

Then there’s HTTP/2, a type of protocol that speeds up web traffic by allowing the transmission of multiple requests in parallel. This improves performance, especially for modern, media-heavy websites.

ACLs (Access Control Lists) and Traffic Filtering

ACLs are the rules HAProxy uses to determine what traffic goes where. In real life, it’s like sorting through emails. Junk mail goes to the trash can or shredder, and your bills go to a specific folder in your drawer.

At the server’s level, you can set conditions to route traffic based on user location, type of request, or even time of day. HAProxy will then help enforce these conditions.

You can even configure the ACLs to block unwanted traffic, such as requests from known malicious sources, or restrict access to certain parts of your service based on IP addresses.

Logging and Monitoring

You certainly don’t expect HAProxy to do all it does without keeping a record of what happened during the shift.

By documenting all traffic and server activity, HAProxy helps you understand how things are running. You can then use this information to track performance, troubleshoot issues, and spot trends early.

It also integrates with monitoring tools like Prometheus and Grafana. These tools help you visualize data and set up alerts so you’re always one step ahead of any potential problems.

Let’s talk about scenarios or environments where HAProxy really shines.

• Web Server Load Balancing: Distributes web traffic across multiple servers. It’s especially suitable for eCommerce platforms and SaaS services that handle huge amounts of traffic. For such websites, even a single minute of downtime can be terrible for business. For perspective, Amazon makes close to a million dollars per minute. For such a business, you can imagine the kind of damage just five minutes of downtime would cause.
• API Gateway: Manages and routes API requests and acts as a reverse proxy for APIs. It receives client requests, forwards them to the appropriate API server, and then returns the server’s response to the client.
• Microservices: Routes traffic between services in a microservices architecture. It’s like a web design agency where different web designers specialize in specific technologies. I’m pretty good at WordPress web design, for example. Someone else at the agency might be a Shopify wizard. HAProxy’s role as the program manager is to make sure that the agency’s designers (microservices) only work on the kind of projects they’re familiar with.
• SSL Offloading: Takes care of SSL encryption. We saw that the backend performs even better when it doesn’t have to worry about carrying the weight of SSL encryption. That’s because HAProxy offloads the encryption at the door. It then reloads it before the response leaves the server to the client.
• DDoS Mitigation: HAProxy controls incoming traffic to protect servers from being overwhelmed by Distributed Denial of Service (DDoS) attacks. These attacks flood a website or service with fake requests, causing them to load annoyingly slowly or even crash. HAProxy implements something called rate limiting to cap the number of requests from a single source. It also conducts traffic filtering to block suspicious or unwanted traffic.

These aren’t the only uses of HAProxy. It also has applications in bot management and web application firewalls.

What if I told you that there are certain things you can do to make this software perform even better?

Implementing Best Practices for HAProxy Configuration

Keep these tips in mind when configuring this software:

• Choose the load-balancing method that fits your needs.
• Keep an eye on performance logs to spot any potential issues.
• Make sure you conduct regular health checks to confirm whether your servers are ready for action when called upon.
• Set reasonable timeouts for connections to avoid keeping servers occupied unnecessarily.
• Enable HTTP/2 if your website handles large amounts of content.
• Use monitoring tools like Prometheus and Grafana to set up alerts and track performance.

Importantly, learn to plan proactively, not reactively. And while you’re at it, remember to monitor continuously.

Using SSL Termination for Secure Connections

SSL termination is a proven way of making sure your data stays safe while lightening the load on your servers. I’ve just started an eCommerce business that I’m pretty excited about.

Let’s say everything goes to plan and the store receives massive amounts of traffic in the near future. Without HAProxy, the servers may not be able to bear the load.

That’s because they have to deal with encrypted connections (SSL/TLS) to protect sensitive data like credit card info and, at the same time, process orders and manage inventory.

The bottom line here is that having HAProxy is a win-win for security and performance. And if you’re running an online business, it could also mean increasing your profits since your store is always available when needed.

Monitoring HAProxy Logs for Insights

Your site visitors shouldn’t know when something’s wrong. This is especially true if it’s something you could have prevented in the first place.

That’s why monitoring is essential. You want to catch these issues and solve them before they become serious. And it’s not just about identifying problems; you also want to learn how to predict potential issues further down the road and stop them and stop them on their tracks.

I can’t think of any other better way of staying ahead of the game than minoring your HAProxy logs. It’s like a treasure map full of valuable information, that is if you know how to use it to your advantage.

Fine-Tuning HTTP Response Handling in HAProxy

Imagine you’re running a Shopify jewelry store on Black Friday. Shoppers flood your site, excited to grab limited-edition gemstone necklaces and earrings. Every click counts. Any slowdown at checkout risks abandoned carts. You don’t want that to be your reputation, especially on a day as big as this for customers and businesses.

Here’s where HAProxy fine-tunes HTTP response handling to keep things smooth. When a customer adds a sapphire necklace to their cart, for example, the response from your backend servers must be quick. HAProxy steps in by setting `keep-alive` headers to maintain persistent connections. This strategy reduces the time it takes for each interaction.

HAProxy improves the efficiency of HTTP response handling through connection keep-alive, reducing the overhead of repeated connections and speeding up response times.

To make things even faster, HAProxy compresses responses. For example, your product images and descriptions for a collection might total 2MB uncompressed. Throw in GZIP compression, and the size shrinks to around 400KB.

What happens is that pages will begin to load quickly, even for mobile users with slower connections. That way, you’ll have a lower rate of abandoned carts. What if shoppers accidentally land on a broken old product URL? Yeah, that’s a big problem, but not when you have HAProxy set up.

HAProxy can automatically issue a 301 redirect to guide visitors to the latest collection. This way, they’ll easily browse your current inventory instead of hitting a “Page Not Found” error.

Most conversations about servers are usually centered around memory and storage. It’s not every day that we hear about heroes like HAProxy.

So next time you see web hosting banners screaming “99.9999% uptime guarantee,” just know that they have some form of load balancing software installed in their servers. If it’s not HAProxy, then it’s probably Nginx.