Health checks

  • Tune
  • Scale 04

Difficulty 2 of 5

Three API nodes serve 2,400 requests/s behind a balancer. Node B fails at 0:20 and stays down for 40 s. The balancer checks every 5 s and needs 3 failed checks. Tune the check to keep availability above 99 percent.

Play level

HTTP/2HTTP/2HTTP/2HTTP/2Users2,400 req/sLoad balanc…1 vCPU · 1 GBNode API2 vCPU · 2 GBNode API2 vCPU · 2 GBNode API2 vCPU · 2 GB
HTTP/2HTTP/2HTTP/2HTTP/2Users2,400 req/sLoad bala…1 vCPU · 1 GBNode API2 vCPU · 2 GBNode API2 vCPU · 2 GBNode API2 vCPU · 2 GB
The board at the start of the level
Three failure domainsTap to fail one replica. The fourth tap heals all.

3 of 3 up · availability 99.9999%

Goals and limits

Availability
at least 99%
p99 latency
under 80 ms
Monthly cost
under 60 USD/mo
Traffic
2,400 req/s

Concepts

How players did

Player results load from the server.

All levels