Bank statement downloads: random 502s and ECS tasks that keep restarting

Banque Nakhil (a fictional online bank headquartered in Rabat) generates PDF account statements with the releves-pdf service: a Node.js API that drives a headless Chromium, on ECS Fargate (cluster prod-nakhil, 3 tasks, 1 vCPU / 2 GB each).

Yesterday at 17:30, a new revision of the task definition was deployed: “added logging parameters and cleaned up the definition based on the platform team's template”.

Since this morning, the customer service center has been reporting 502 errors when businesses download their annual statements. Individual customers, on the other hand, have no problem. The service dashboard shows “comfortable” memory.

You are on your workstation with the AWS CLI v2 (region eu-west-1).