NGINX vs. HAProxy: Comparing Features and Use Cases

NGINX and HAProxy share much in common at a high level: Both are open source technologies used to manage web traffic. However, the more specific the use case and volume of data, the more the minor differences become significant. This is when weighing the benefits and drawbacks of NGINX vs. HAProxy can be beneficial.

In this blog, our expert highlights the key differences between NGINX vs. HAProxy and explains how to determine which is more suitable for your website or application. 

Note: While both NGINX and HAProxy have commercial versions (NGINX Plus and HAProxy Enterprise), this blog is focused on the FOSS versions. 

NGINX vs. HAProxy: Overview

The main difference between NGINX vs. HAProxy is that while both are effective as load balancers and reverse proxies, NGINX is a web server with broader range of capabilities, making it more versatile. HAProxy is ideal for complex load balancing scenarios where high throughput and low latency are needed to manage a high volume of web traffic. 

The key technical differences between NGINX and HAProxy come into play in two areas: the efficiency of the worker processes and load balancing health checks of the next endpoint. The latter is particularly limited in NGINX (less so in NGINX Plus, which has a number of premium features left out of the free OSS version). 

What Is NGINX?

NGINX is an HTTP web server, reverse proxy for TCP/UDP and web traffic, and mail proxy server. It's characterized by its lightweight footprint, and efficient and modular design.

What Is HAProxy?

HAProxy is a layer 4 TCP proxy and an HTTP gateway/reverse proxy that can handle HTTP 1.1, HTTP2, and HTTP3 requests/responses on either end and a combination of protocols. Due to its queue design and features, HAProxy can terminate TLS and normalize HTTP and TCP traffic. 

While there are many use cases where HAProxy shines, it is not capable of per-packet load balancing or serving static web content, nor is it a good fit as a dedicated, large-scale caching proxy.

NGINX vs. HAProxy: Key Similarities and Differences

When it comes to reverse proxying and load balancing, there are more similarities than differences between NGINX and HAProxy. However, we’ll explore a few areas where the two technologies differ and when/why it matters.

Architecture

NGINX and HAProxy both utilize event-driven architecture, though HAPRoxy has a multi-threaded single process design and NGINX uses dedicated worker processes.

Configuration 

NGINX uses a hierarchical block structure for configuration. The main NGINX configuration file is typically nginx.conf with additional configuration loaded in a separate file (for example, the TLS configuration). The directives in the configuration blocks are structured in key-value pairs and encapsulated in curly brace blocks. 

The main contexts are http, server, and location. The context is inherited from parent context and directives have priorities. When building more complex ‘location’ and ‘match’ logic, the directive order and priority is often overlooked.

Here are some best practices for location blocks in NGINX:

• Use exact matches for static pages that you know won’t change.
• Utilize regular expressions for dynamic URI matching but be aware of the order of precedence.
• Prefix matches (^~) can be used for performance benefits if you do not need regular expression matches.
• Root-level (/) location should be your fallback option.

The most common issues when configuring location blocks in NGINX include:

• Regular expressions evaluated out of order can lead to unexpected results.
• Overusing regular expressions can degrade performance.
• Prefix directives without the ^~ modifier may be overridden by regular expressions.

Get more NGINX setup and configuration tips >>

Now let's compare to HAProxy, which uses a flat section-based configuration. The configuration file for HAProxy is commonly haproxy.cfg. The main sections are global, defaults, frontend, backend, and listen.

Some common issues to be aware of regarding HAProxy configuration:

• Not using graceful reload to avoid connection interruptions.
• Lack of observability implementation for the golden signals of the HAProxy Frontend and Backend systems (Latency, Service Saturation, Errors, and Traffic Volume).

Key difference: HAProxy configuration tends to be more specific to load balancing and proxying, while NGINX configuration can cover a broad range of web server functionalities that HAProxy lacks.

Performance

When evaluating the performance of NGINX vs HAProxy, the differences are pretty nuanced, and comparable only on a use case by use case basis. Generally speaking, they are both considered high-performance in terms of delivering content to clients and users. 

There are some features of HAProxy that can be useful in scenarios where NGINX does not have an equivalent function. For example, HAProxy's design with multiple threads on the same process allows it to share resources among the processes. This is advantageous when many different clients access similar endpoints that share resources or web services.

Scalability

Again, both NGINX and HAProxy are highly scalable. One drawback of NGINX is that each request can only be served by a single worker. This is not optimal use of CPU and network resources. Because of this request-process pinning effect, requests that do CPU-heavy or blocking IO tasks can slow down other requests.

Security 

HAProxy offers fine-grained Access Control List (ACL) configurations via a flexible ACL language. NGINX, on the other hand, uses IF statements for routing.

For observability, NGINX relies on logging, and an OpenTelemetry module can be added during build time, whereas HAProxy offers a native API and statistics on demand.

Learn more about web server security >>

Support

Both NGINX and HAProxy have a very large user bases and communities, and are being actively developed with new features (e.g. QUIC, HTTP/3) and updated regularly with security patches. Additionally, both also have active Github projects with discussion forums where users can submit questions and share feedback on features.

For teams that need immediate, expert-level remediation beyond what OSS communities provide, OpenLogic offers SLA-backed technical support up to 24/7/365 for both NGINX and HAProxy. 

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Use Cases: NGINX vs. HAProxy

On a qualitative basis, NGINX is the go-to option for fast and simple builds. This is also why NGINX is so popular as an ingress controller in Kubernetes and edge deployments.

While HAProxy will cover all the same use cases as NGINX, it is more feature-rich as a reverse proxy. For example, you could use HAProxy for a layer 4 database frontend for a MySQL cluster/replication architecture, multiple monolithic web applications or services, DNS cache, and initial Denial of Service protection via queueing. SRE Engineers will appreciate the detailed real-time metrics and monitoring capabilities in HAProxy as well. 

Using NGINX and HAProxy Together

In large, data-intensive distributed architectures, there are some use cases where the upsides of combining the strengths of NGINX and HAProxy are appealing. However, there are also some drawbacks worth considering. 

Use cases

• High-traffic websites and microservices requiring both content delivery and load balancing
• Applications with mixed static and dynamic content, especially beyond web type content

Upsides

• Complementary strengths: NGINX excels at content caching and serving static content, while HAProxy is optimized for load balancing.
• Enhanced security: NGINX can act as a reverse proxy, adding an extra layer of security before requests reach HAProxy.
• Flexibility: This setup allows for more complex architectures and fine-tuned control over traffic flow.

Drawbacks

• Increased complexity: Managing two separate systems can be more challenging.
• Potential bottlenecks: If not configured properly, the additional layer can introduce latency.
• Higher resource usage: Running both services requires more server resources.
• Configuration challenges: Ensuring both systems work harmoniously together can be tricky.

Final Thoughts

Hopefully it is now clear that comparing NGINX vs. HAProxy is a worthwhile exercise. There are use cases that favor each, as well as situations when deploying them together can be an effective strategy. Most agree that the learning curve for NGINX is less steep, with easier setup and configuration, so for simpler applications delivering static content where speed is prioritized over complexity, NGINX works. However, for applications that require real-time responsiveness and high availability, and teams that want more advanced customization for traffic routing and better observability, HAProxy is probably a better fit. 

Additional Resources

• Webinar - Open Source Web Infrastructure: Current Ecosystem and Trends
• Guide - Overview of Open Source Web Infrastructure
• Blog - Top Open Source Infrastructure Technologies 
• Blog - NGINX Performance Tuning: Top 5 Tips
• Course - NGINX Training 
• Blog - Apache vs. NGINX