How the project works ?

• You have 3 "Express" servers and a "load balancer" sitting infront of them.
  

• This command "curl http://localhost:80" calls the load balancer, then the load balancer will forward that request to servers according to RR (Round Robin) algorithm:
  

• 1st request => 1st server
  

• 2nd request => 2nd server
  

• 3rd request => 3rd server
  
  
  

How to run the project on your machine ?

Follow these tips:

• clone the repo
• npm install
• Generate ".env" file and allocate these variables to unused ports on your local machine:
  
  • SERVER_PORT=
  • LOAD_BALANCER_PORT=
  • SECOND_SERVER_PORT=
  • THIRD_SERVER_PORT=
• npm run dev

How to use the project works?

• Once you run the command "npm run dev".

• When you send an HTTP request to the load balancer by:
  

  • curl http://localhost:LOAD_BALANCER_PORT/
    

• It will forward the request to the active servers and you will get hello from server...
  according to RR algorithm.

• This command is responsible for checking the health of server:
  

  • curl http://localhost:PORT_NUMBER/health-check
    

• when you run the previous command you will get a response contains details abt you server.

• Try to kill one of the servers(by uncommenting "throw new Error()" in "healthChecker.ts") and run this cmd:

• curl http://localhost:PORT_NUMBER/health-check
  and the broken server will be out.

Steps to use Dockerfile for the application

docker build -t image-name:tag .

docker run -itd -p host_port:container_port --env-file .env image-name:tag

Steps to use docker compose

docker-compose up -d