cryexc-snap

HTTP service that captures screenshots of the cryexc footprint chart using a headless Chromium browser. A single GET /api/screenshot request returns a PNG of the configured chart, ready for use in dashboards, bots, or alerting pipelines.

How it works

• Launches a headless Chromium instance via go-rod
• Navigates to the cryexc footprint widget with chart settings embedded in URL params
• Waits for the public/footprint network response (confirming data has loaded) before capturing
• Returns the screenshot as image/png

Endpoints

Method	Path	Description
GET	/api/screenshot	Capture and return a PNG screenshot
GET	/status	Health check — returns {"ok": true}

The screenshot endpoint accepts an optional ?delay=N query param (seconds) to override the default 2s post-load render wait.

Flags

Flag	Default	Description
--port	19847	Port to listen on
--cryexc-url	(built-in)	Full cryexc URL; configurable params below override it
--tick-size	25	Footprint tick size in USD
--history	3h	History window as a duration (1h, 90m, 2h30m)
--viewport	2560x1440	Browser viewport as WxH
--prefetch-browser	—	Download the headless browser binary and exit

Running locally

go run . --tick-size 25 --history 3h

Then capture a screenshot:

curl -o screenshot.png http://localhost:19847/api/screenshot

Running tests

./run_test.sh          # unit tests
./run_test.sh live     # end-to-end tests against the real cryexc site
./run_test.sh all      # both

Live tests save the captured screenshot to testdata/screenshot.png.

Docker

docker build -t cryexc-snap .
docker run -p 19847:19847 cryexc-snap

The image prefetches the headless browser at build time so the container starts cleanly with no network dependency at runtime.

Deployment

A Kubernetes Deployment and Service manifest is provided in k8s/. The --cryexc-url flag can be overridden via the CRYEXC_URL environment variable defined in the manifest.