Telegraf upgrade-charm does not upgrade the dashboards in Grafana

[Xav Paice]

With the current master branch, when I make a dashboard update to the templates/dashboards/grafana/Telegraf.json.j2 template I expect to upgrade the Telegraf charm and have that update the dashboard in Grafana.

I did find one typo in the register_grafana_dashboard() @when conditions, and have a patch ready, but even though that's patched and register_grafana_dashboard() runs, it doesn't actually update the dashboard in Grafana.

Environment: master branch of Telegraf charm, bionic, and cs:~llama-charmers-next/grafana-14.

[Xav Paice (xavpaice)]

Change https://code.launchpad.net/~xavpaice/charm-telegraf/+git/charm-telegraf/+merge/400008 adds a digest to the data exported across the dashboards relation so that Grafana knows it's been updated. I've marked the Grafana charm invalid in this bug report since there's no change to make to Grafana in this respect, and put Telegraf back to in-progress while we work on the latest change.