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The Reliable, High Performance TCP/HTTP Load Balancer
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What is HAProxy?

HAProxy (High Availability Proxy) is a free, very fast and reliable solution offering high availability, load balancing, and proxying for TCP and HTTP-based applications.
HAProxy is a tool in the Load Balancer / Reverse Proxy category of a tech stack.

Who uses HAProxy?

638 companies reportedly use HAProxy in their tech stacks, including Instagram, Twitter, and reddit.

1418 developers on StackShare have stated that they use HAProxy.

HAProxy Integrations

Datadog, Netdata, Tutum, Honeycomb, and Server Density are some of the popular tools that integrate with HAProxy. Here's a list of all 8 tools that integrate with HAProxy.
Public Decisions about HAProxy

Here are some stack decisions, common use cases and reviews by companies and developers who chose HAProxy in their tech stack.

James Cunningham
Operations Engineer at Sentry · | 17 upvotes · 28.8K views
Shared insights

When accepting events, we would be crazy to just expose the Python web process to the public Internet and say, “Alright, give me all you got!” Instead, we use two different proxying services that sit in front of our web machines:

1) NGINX, our product-aware proxy, handles many of the upper bounds that we have deemed reasonable. It is responsible for a variety of bounds, but its most popular one is protecting Sentry from exceedingly large event volumes. Ever so often, a user will run into a problem where they’ve deployed their code out into the abyss, and their event volume clocks in at a few zeroes higher than what they signed up for.

2) In front of NGINX, we use another proxying service called HAProxy, which acts as a delta of connections without any of that product awareness logic and has a lot higher throughput. All it does is accept connections and send them off to different NGINX servers, allowing us to gracefully add or remove NGINX servers as we see fit.

#WebServers #LoadBalancerReverseProxy

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Tom Klein

We're using Git through GitHub for public repositories and GitLab for our private repositories due to its easy to use features. Docker and Kubernetes are a must have for our highly scalable infrastructure complimented by HAProxy with Varnish in front of it. We are using a lot of npm and Visual Studio Code in our development sessions.

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Around the time of their Series A, Pinterest’s stack included Python and Django, with Tornado and Node.js as web servers. Memcached / Membase and Redis handled caching, with RabbitMQ handling queueing. Nginx, HAproxy and Varnish managed static-delivery and load-balancing, with persistent data storage handled by MySQL.

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John Kodumal

Over the past year, we've shifted our philosophy on managed services and have moved several critical parts of our infrastructure away from self-managed options. The most prominent was our shift away from HAProxy to AWS's managed application load balancers (ALBs).

As we scaled, managing our HAProxy fleet became a larger and larger burden. We spent a significant amount of time tuning our configuration files and benchmarking different Amazon EC2 instance types to maximize throughput.

Emerging needs like #DDoS protection and auto scaling turned into large projects that we needed to schedule urgently. Instead of continuing this investment, we chose to shift to managed ALB instances. This was a large project, but it quickly paid for itself as we've nearly eliminated the time spent managing load balancers. We also gained DDoS protection and auto scaling "for free".

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The frontline API is proxied through a HAProxy load balancer with NGINX as the fronted, which also handles SSL termination. This frontline API consist of 600 stateless endpoints that join together multiple services.

As part of the Marketplace stack, engineers in this area integrate with various other internal services, including logtron to log to disk and Kafka and uber-statsd-client, the Node.js client for statsd.

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Shared insights

Early 2013

In early 2013, Airbnb tackled the problem of service discovery and load balancing in the context of a service oriented architecture (SOA) by building and releasing an open source tool called SmartStack. SmartStack is built on two other open source tools created by Airbnb called Nerve and Synapse.

Nerve is a service registration daemon that performs health checks that “creates ephemeral nodes in Zookeeper which contain information about the address/port combos for a backend available to serve requests for a particular service.”

Synapse is a transparent service discovery framework for connecting an SOA that reads the information in Zookeeper for available backends, and then uses that information to configure a local HAProxy process, which then routes requests between clients and services.

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HAProxy Alternatives & Comparisons

What are some alternatives to HAProxy?
nginx [engine x] is an HTTP and reverse proxy server, as well as a mail proxy server, written by Igor Sysoev. According to Netcraft nginx served or proxied 30.46% of the top million busiest sites in Jan 2018.
A modern HTTP reverse proxy and load balancer that makes deploying microservices easy. Traefik integrates with your existing infrastructure components and configures itself automatically and dynamically.
Originally built at Lyft, Envoy is a high performance C++ distributed proxy designed for single services and applications, as well as a communication bus and “universal data plane” designed for large microservice “service mesh” architectures.
Squid reduces bandwidth and improves response times by caching and reusing frequently-requested web pages. Squid has extensive access controls and makes a great server accelerator. It runs on most available operating systems, including Windows and is licensed under the GNU GPL.
Varnish Cache is a web application accelerator also known as a caching HTTP reverse proxy. You install it in front of any server that speaks HTTP and configure it to cache the contents. Varnish Cache is really, really fast. It typically speeds up delivery with a factor of 300 - 1000x, depending on your architecture.
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HAProxy's Followers
1626 developers follow HAProxy to keep up with related blogs and decisions.