With a custom "graphite" datasource, Browser Access Mode spinning (but Server Access mode renders fine!)

Hi. I’m using Grafana v5.2.1 (commit: 2040f61), and have written a simple python TornadoServer/4.5.3 to emulate a graphite datasource, e.g. /render?format=json&....

When I set the datasource to Server access mode, Grafana fetches and renders the graph perfectly. But if I change it to Browser access mode, Grafana spins the icon in the upper left of the panel, in both Chrome and Firefox, and never renders the graph.

The Grafana Query Inspector is blank, but using Chrome’s Developer Tools to see the /render request and response on the network, it has completed, status 200, and appears identical to responses from a real graphite data source. I have tried with both small and large # datapoints.

Anyone out there with knowledge of the Grafana javascript concerning Browser Access Mode that might have any pointers to help debug this? Thanks in advance!

Sounds like a CORS issue.