flo_lb

README

Example of toy load balancer for educational purposes.

The current version round robins between hardcoded backends, without checking for their health.

Testing setup

Open 4 terminal windows and then run in each respectively:

Terminal #1

Run the first test server backend on localhost:8081

florinbalin@DESKTOP:flo_lb$ go run ./example/server/main.go --name=Server1 --port=8081

Terminal #2

Run the second test server backend on localhost:8082

florinbalin@DESKTOP:flo_lb$ go run ./example/server/main.go --name=Server2 --port=8082

Terminal #3

Run the load balancer and make it point to the two servers:

florinbalin@DESKTOP:flo_lb$ make build && make build

The load balancer will listen by default on port :8080 and round robin requests to the two backends. You can change the behaviour in the configs/prod.textproto config file.

Terminal #4

Start doing http requests to the load balancer using curl:

florinbalin@DESKTOP:~$ for i in {1..5}
do
curl http://localhost:8080/hello
done

Watch the logs of the servers, load balancers and the responses to know what is happening.

Note for running the load balancer within a container

Listening to http://localhost would resolve to the container localhost. Therefore, https://hub.docker.com/r/florinbalint/flo-lb tries to connect to host.docker.internal by default instead. If that does not resolve to your localhost you can add it manually with -d --add-host host.docker.internal: host-gateway when running locally.