Today @jeena hit a snag when updating a chart: the new version 0.0.2 didn't show up on ChartMuseum until I manually purged the URL from the CDN, despite it having been over half an hour since the patch was merged.
Using mwscript purgeList.php to manually purge the URL in question fixed things.
The CDN definitely caches the responses:
✔️ cdanis@localhost ~ 🕒☕ curl -sIXGET https://helm-charts.wikimedia.org/stable/api/charts/rdf-streaming-updater HTTP/2 200 age: 88 x-cache: cp1081 miss, cp1087 hit/2 [...]
From the CDN's POV, ChartMuseum doesn't send a Cache-Control header at all:
so I believe these all get cached for the default_ttl of 24h. That seems far too long.
I think ChartMuseum should be configured to send a Cache-Control response header that specifies s-maxage of approx 1 to 5 minutes.