Problems / Kubernetes and containers, medium
The API scales on CPU from 4 pods, and new pods need a node that takes about a minute to start. At 30 s a flash sale brings 3× traffic all at once.
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Keep success at 99% or more through the flash sale.
Like a coding problem, a solution has to pass every case, not just the one it was built for. Submit in the lab runs all 3; 1 of them are hidden until then.
120 requests a second for 180 seconds: 100% api (reads).
What each component does in this design, and what calls it. The simulator mimics each one from these settings.
| Component | Its job here | Settings |
|---|---|---|
| Load balancerLoad balancer | Traffic enters here.Calls API (pods).Layer 4 balancers route by IP and port; layer 7 balancers read HTTP and can route by path or header. | – |
| API (pods)Container platform | Load balancer forwards to it.Calls Postgres.Kubernetes places pods on nodes by their CPU and memory requests, and only replaces a lost node's pods after about 5 minutes. | 20 slots |
| PostgresSQL database | API (pods) calls it.Postgres runs one process per connection, which is why poolers like PgBouncer sit in front of busy databases. | 32 vCPU · 300 connections |