Interactive Debugging Simulator
User Request
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Frontend
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API Gateway
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Database
[10:00:01] SYSTEM Simulator initialized. Click a component to inspect its logs.
Investigation Console
A user reported that they are seeing a "Login Failed" message on the website. Your job is to trace the request through the system to find where it's breaking.
How to Debug this System
In professional software development, you rarely have just one file to look at. You have to trace a request through multiple “layers”.
The Strategy: Tracing the Flow
- Start at the UI: What did the user see? What request did the browser send?
- Check the API Gateway: Did the request reach the server? If so, what did the server try to do?
- Inspect the Backend Logic: Did the code crash? Did it fail to talk to a dependency?
- Verify the Infrastructure: Are the databases, caches, and third-party services running?
Common Red Herrings
Sometimes the error message you see isn’t the real problem.
- A 500 error in the browser just means “something went wrong on the server”.
- A Connection Refused error in the API logs usually means the next service in line (the database) is down.
Real-World Tip
When you find an error like No space left on device, the solution isn’t just to restart the database. It’s to find out what filled up the disk (usually logs) and clean it up!