no option for zero-based graphs

[robey]

I thought there was consensus that graphs should start at 0 on the Y axis to avoid misinterpretation, but a quick google search shows that there's not total agreement on that.

So, I would like the option to make the graph zero-based, without forcing everyone else to agree. :)

For some stats (like "users online"), the graph may stay flat for hours at a time. Currently, prometheus will draw such a graph as blank, with a minimal Y range, and a single line at the baseline where it's effectively invisible.

[juliusv]

Agreed. I believe 0-based is the default in PromDash (vs. Prometheus itself), though it's possible to manually set a Y-axis range (but no option to simply dynamically clamp the Y-axis to the available values).

0-based Y-axes have the problem that very large counters will just look like flat lines even if they're increasing rapidly. But yeah, the reverse problems also exist.

So I think this might actually be worth another UI button, both in Prometheus and in PromDash.

[brian-brazil]

Note that http://prometheus.io/docs/visualization/consoles/#graph-library has a min option.

[juliusv]

Yeah, it's less about the graphing library support than about the question of what UI elements to add to get a balance between UI clutter and really needed features (for the server-side built-in graphing at least).

[brian-brazil]

I think for /graph we should do something a bit more reasonable when all the values are the same, such as say making the main and max 10% either side of the value.

[discordianfish]

I just realize how problematic this can be: "Peaks in the metrics are lower than they appear" :)
Do we have consensus how it should look like? Making it 10% will help with the invisible steady metric but won't change that it's sometime visually misleading. I guess a simply checkbox with whatever default would make most sense since I believe there are scenarios for both.

[matthiasr]

another case: stacked graphs should always include the zero line. Right now I'm looking at a stacking of 5 up == 1 and it's … weird.

[theophani]

@matthiasr A stacked graph was exactly what I was looking at when we discussed this yesterday in our company channel. Maybe that is a nice mini-change.

In this graph, I was trying to understand the contribution that the green area contributed to the whole. For a moment, I was convinced it contributed more than half.

I understand the desire to see “the interesting” part of the graph in detail, but I think that should be an active choice, not the other way around.

[discordianfish]

This seems easy to fix. Are we in agreement that it should be changed? And how is it suppose to look? Just another button beside [ ] Stacked? I'd also say we make it default for all graphs.

[matthiasr]

👍