Per the advice we got on T370739, we should explore what it would entail to set up a service-runner-based Node service to render charts.

• Prototype a service that:
  • uses service-runner
  • does request routing the way service-template-node does it
  • has a health check endpoint
  • has an endpoint that renders a chart from a JSON specification
  • is stateless
  • doesn't send requests to MediaWiki (or to anything else)
• Write down any questions that come up, so we can ask SRE