02 · The application, in containersLab 12 / 59
Challengenetworking
Reverse Proxy & Load Balancing with Nginx — Challenge
Put a proxy in front of two backends, then break one and watch what the health check does about it.
- Time
- 25 min
- Level
- Intermediate
- Objectives
- 4 objectives
- Cost
- Free
Where this fits in the platform
This lab adds
- Traffic spread across replicas, and a failing one taken out
Which lets you
Before you start
You will need
- Docker
- Docker Compose
You do not need these already — the lab environment below provides them.
You will be able to
- Configure an upstream with more than one backend
- Forward the headers an application needs to see the real client
- Explain 502 versus 504 from the proxy's point of view
The goal#
Achieve the same outcome as Reverse Proxy & Load Balancing with Nginx, from an empty starting point, without the steps.
One application server is a single point of failure, and it also has to terminate TLS, serve static files and survive a restart.
A reverse proxy in front solves all three — and introduces its own failure modes, which are the ones you will actually debug in Kubernetes later.
Hands-on environment
Run this lab in a real terminal, free and in your browser. The environment is temporary and yours alone — break it as much as you like.
Start the challengeOpens in Killercoda, in a new tab — keep this page open for the steps.
This is the guided lab's environment — the same machine, with its walkthrough on the left. Work from the task above and leave those steps alone until you are done, or you are reading the answers.
Run it on your own machine
Run this lab on your own machine. One command starts the environment, with everything the lab needs already installed:
You will need:
- bash
- curl
git clone https://github.com/EgyKode/EgyKode-lab.git
cd EgyKode-lab
./egykode start
./egykode shellYou need Docker and Git installed. Everything else runs inside the environment. The first start downloads it and takes a few minutes; later starts are seconds.
Not sure what you already have? Run: npm run doctor — it checks and changes nothing.
Anything you tick here is your own record. EgyKode cannot see inside that terminal, so the success criteria stay self-assessed even when the environment checks your work for you.
What must be true when you are done
Step 1 of 3
What must be true when you are done#
- Requests through the proxy reach both backends, demonstrated by repeated calls.
- Stopping one backend does not produce errors for the client.
- The backend can see the original client IP, not the proxy's.
- You can produce a 502 and a 504 deliberately and explain the difference.
Rules#
- Do not open the guided lab until you are finished, or until the same problem has held you up for 20 minutes.
- Documentation is allowed and encouraged.
- Verify every criterion with a command whose output you can read.
If you get stuck#
- What did you expect, exactly?
- What happened instead — the error text, not a paraphrase?
- Which layer is that error from?
- What is the smallest command that proves the layer below is fine?
You are done when
0 of 4
The concept behind it
Next up
Lab 12 of 59 on the project path