Fetch anything

  • Fix
  • Lock 16

Difficulty 4 of 5

Users paste an image URL and the fetcher downloads it, 300 fetches/s. Some URLs point at internal addresses, and the fetcher reads them too. No request may reach an internal service, and fetches must keep under 0.1 percent errors and p99 under 300 ms. 5 edits.

02:14. Cloud keys used from an unknown address. Logs show the image fetcher read the metadata service. Graph: requests to metadata.

Play level

HTTP/2HTTP/2HTTP/2HTTP/2Users304 req/sAPI server2 vCPU · 2 GBNAT gateway1 vCPU · 1 GBAPI server8 vCPU · 8 GBAPI server1 vCPU · 1 GBAPI server1 vCPU · 1 GB
HTTP/2HTTP/2HTTP/2HTTP/1.1HTTP/2Users304 req/sAPI serverNAT gatewayAPI serverAPI serverAPI server
The board at the start of the level
A reader with no tools stops page ordersTap or press Space to add or remove the reader

Separate reader · 0 of 100 attacks reach a tool

Goals and limits

Forbidden reach (Attack)
none
Forbidden reach (Probe)
none
Error rate (Fetch)
under 0.1%
p99 latency (Fetch)
under 300 ms
Monthly cost
under 100 USD/mo
Parts you can add
API gateway, Load balancer (L7)
Part limit
10
Edit limit
5
Traffic
300 req/s

Concepts

How players did

Player results load from the server.

All levels