load-testing.md

Load Simulation Guide

This project includes a Docker Compose setup with three backend echo servers and the Go load balancer in front of them. Use the commands below to simulate traffic against the balancer and observe how requests are distributed.

Start the stack

Run the full setup from the project root:

docker compose up --build

The balancer is published on http://127.0.0.1:8080/.

Send a single request

Use curl to confirm the balancer is up and forwarding to a backend:

curl -v http://127.0.0.1:8080/

Simulate many connections

The simplest way to create many separate TCP connections is to run multiple curl requests in parallel.

Moderate load

seq 1 50 | xargs -n1 -P10 curl -s http://127.0.0.1:8080/ > /dev/null

Heavier load

seq 1 500 | xargs -n1 -P50 curl -s http://127.0.0.1:8080/ > /dev/null

Background burst

for i in $(seq 1 200); do curl -s http://127.0.0.1:8080/ >/dev/null & done
wait

Keep connections open longer

If you want to stress the L4 relay for longer, make the backend responses slower. In docker-compose.yml, set RESPONSE_DELAY for each backend to something like 2s or 5s, then restart Compose.

What to watch

The balancer logs should show L4 activity such as:

• backend selection
• relay start and finish
• backend dial failures
• connection resets or copy errors

The backend containers will only show request logs if the backend service itself logs them.

Optional load tool

For repeatable load testing, you can use a dedicated tool such as hey:

hey -n 1000 -c 50 http://127.0.0.1:8080/

If hey is not installed, the curl commands above are enough to generate concurrent connections.