[Uptime] Fix partial buckets in graphs

[andrewvc]

Our charts often have partially filled buckets for the most recent values. This looks weird. @makwarth originally reported this. AFAIK this is normal across much of Kibana. It seems to me that the only 'fix' would be chopping off the most recent bucket, however then we'd be showing less data.

Thoughts on approaches here @justinkambic and @makwarth ?

[elasticmachine]

Pinging @elastic/uptime

[makwarth]

In APM, the last bucket is chopped off. The user will miss some data, but having the graph look like your site is down is worse. The ideal solution is to not chop it off, but mark it as incomplete, like in Discover, but we haven't gotten to that yet. (Works best for bar charts)

[andrewvc]

@makwarth my worry with chopping things off is that in uptime people are pretty sensitive to what the state now is far more than what it was.

Maybe a compromise is showing the last bucket if some data is present, but not showing it if not. Also, we would show empty data if the two most recent buckets are empty, which could indicate a broken check. WDYT? The two bucket check wouldn't work totally right unless the bucket size was synced to the heartbeat check interval, but it'd work for longer timescales.

[makwarth]

@andrewvc I can see arguments for either way, but I would worry about showing partial data without flagging it. A user might be thinking "why do I only have half the amount of checks all of a sudden?" and be alarmed.

[andrewvc]

@makwarth I agree. Maybe we could indicate that the final segment is partial somehow? Perhaps we could make the last part of the chart semi-transparent or something?

This feels like it should be an EUI charts feature.

[makwarth]

Agree. We chopped the last bucket in APM, and decided to wait for EUI to solve this.