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Production is down. Can you fix it?

A guided 502 incident you can solve in about 60 seconds - no signup. Follow the green “do this next” button at each step (it runs the command for you), or type the commands yourself. Four steps: reproduce it, find the cause, fix the port, reload.

1

Reproduce the outage

First, confirm the problem. Send a request and watch it fail with 502.

click to run, or type it yourself
demo-lab: 502 bad gateway
INVESTIGATING
ProdDown preview - a guided 502 incident (no signup).
Scenario: 502 Bad Gateway Difficulty: Easy Severity: SEV-2
 
Users get a 502 Bad Gateway on every request. Nginx is up; the app was
redeployed 30 min ago. Find the root cause and restore the service.
 
Not sure where to start? Just click the highlighted button below the
terminal - it runs the right command for you. Or type it yourself.
 
root@proddown-lab:~#
Quick run:
Press Enter to run · Tab to autocomplete · type hint anytime

Your objective

Make curl http://localhost return 200 OK.

  • Reproduce the 502 (curl)
  • Inspect the nginx config
  • Fix the wrong upstream port
  • Reload nginx & verify 200
Progress0/4

Real terminal skills

The same commands you'd run on a live box: curl, cat, ss, nginx.

Root-cause driven

No multiple choice. You diagnose and fix, we verify the outcome.

Under pressure

Real labs add a countdown timer, grading, hints, and a shareable report.

Preview mode - a guided walkthrough. Sign up free for a live container with real root access.

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