Design a load balancer that acts as a Reverse Proxy and balances the load across multiple configured backend servers.
The problem statement is something to start with, be creative and dive into the product details and add constraints and features you think would be important.
- ability to accept incoming TCP connection and forward it to one of the configured backend server
- ability to add and remove backend servers at will
- ability to monitor healthy backend servers
- ability to have a configurable load balancing strategy
- ability to measure and monitor load balancer metrics
- should scale to millions of concurrent TCP connections
- make your high-level components operate with high availability
- ensure that the data in your system is durable, not matter what happens
- define how your system would behave while scaling-up and scaling-down
- make your system cost-effective and provide a justification for the same
- describe how capacity planning helped you made a good design decision
- think about how other services will interact with your service
- ensure the data in your system is never going in an inconsistent state
- ensure your system is free of deadlocks (if applicable)
- ensure that the throughput of your system is not affected by locking, if it does, state how it would affect
Create a design document of this system/feature stating all critical design decisions, tradeoffs, components, services, and communications. Also specify how your system handles at scale, and what will eventually become a chokepoint.
Do not create unnecessary components, just to make design look complicated. A good design is always simple and elegant. A good way to think about it is if you were to create a spearate process/machine/infra for each component and you will have to code it yourself, would you still do it?
To understand the nuances and internals of this system, build a prototype that
- is a working load balancer
- has an interface to
- add and remove backend servers
- see which of the configured backend servers are healthy
- visualize load balancer metrics
- change load balancing strategy on the fly
- changes should not require a reboot to take effect
This is a recommended tech-stack that will help you building your Load Balancer effetively
| Which | Options |
|---|---|
| Language | Multi-threaded language like Golang, Java, C++ |
These are the common pitfalls that you should keep in mind while you are building this Load Balancer
- System calls are blocking
- System Calls
- Internals of Load Balancer
- Concurrent Execution using Multi-threading
If you find this assignment helpful, please
- share this assignment with your friends and peers
- star this repository and help it reach a wider audience
- give me a shoutout on Twitter @arpit_bhayani, or on LinkedIn at @arpitbhayani.
This assignment is part of Arpit's System Design Masterclass - A masterclass that helps you become great at designing scalable, fault-tolerant, and highly available systems.