Adding a grafana-image-renderer to scylla-monitoring

[fruch]

grafana has a build-it plug that can help us capture panels or dashboards
https://grafana.com/docs/grafana/latest/administration/image_rendering/#run-in-docker

up until now, we are doing all kind of hacks, using selenium and such to capture the dashboards as images.

this seems to work much better, and I think it would be a nice addition to scylla-monitoring

[fruch]

example of using it:

LOCAL_HOST_IP=192.168.1.14

docker run -d -p 8081:8081 grafana/grafana-image-renderer

./start-all.sh -c GF_RENDERING_SERVER_URL=http://${LOCAL_HOST_IP}:8081/render -c GF_RENDERING_CALLBACK_URL=http://${LOCAL_HOST_IP}:3000/ -c GF_LOG_FILTERS=rendering:debug

curl http://localhost:3000/render/d/cql-3-3/scylla-cql?orgId=1&refresh=30s&from=1587680332029&to=1587680632029&width=1000&height=2500 > dashboard.png

[amnonh]

It is nice, but it means running an additional container just for snapshots.

You can still add this to the QA testing without adding it by default to the monitoring stack.

[amnonh]

Relates to #248
https://grafana.com/grafana/plugins/grafana-image-renderer

[amnonh]

One annoying part is the configuration. Both containers need to know each other IPs, this can be done either using the host IP (not always clear) or with a docker-compose