Simple "Moving Average"?

[Dave Cadwallader]

Looking for some advice on smoothing out a spikey graph based on gauges.

Given these two metrics:

• instances_total{state="busy"}
  
• instances_total

We want to plot the ratio of "busy" instances over time.

This query produces the expected result, broken down by AWS region:

sum(instances_total{state="busy"}) by (region) / sum(instances_total) by (region)

But the graph is pretty spikey.  What would you recommend to apply a smoothing factor to make it more readable over a longer interval?  We looked at the holt_winters function, but it seemed to require a range vector and our query produces an instant vector.  Ideally we're looking for something simple like a "5 min moving average".

Thanks!
Dave

[Ben Kochie]

If you're using Grafana, there's a handy $__interval variable

It seems like your instances_total is a gauge. We recommend _total be reserved for counters to make them easy to identify.

If it is a gauge, you can do something like this:

sum(avg_over_time(instances_total{state="busy"}[$__interval])) by (region)

That should give you the rolling average of the gage, matched to the step in Grafana.

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[Dave Cadwallader]

I've been using Grafana for 4 years, and I never knew about $__interval!  This was a mind-blowing answer.  Your solution worked perfectly.  Thanks for being awesome, Ben!

[Tristan Colgate]

It's also helpful to make sure you set the min step when using $__interval. This usually results in less things breaking when you zoom in too close.

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