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Merged
merged 2 commits into from
Mar 20, 2024
Merged

Basic native histogram utilities #1164

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Basic native histogram utilities
krajorama Mar 14, 2024
4e837df
Merge branch 'master' into krajo/basic-native-histogram-utils
krajorama Mar 20, 2024
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36 changes: 36 additions & 0 deletions grafana-builder/grafana.libsonnet
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Original file line number Diff line number Diff line change
@@ -1,3 +1,5 @@
local utils = import 'mixin-utils/utils.libsonnet';

{
dashboard(title, uid='', datasource='default', datasource_regex=''):: {
// Stuff that isn't materialised.
Expand Down Expand Up @@ -70,6 +72,40 @@
},
},

addShowNativeLatencyVariable():: self {
templating+: {
list+: [{
current: {
selected: true,
text: 'classic',
value: '1',
},
description: 'Choose between showing latencies based on low precision classic or high precision native histogram metrics.',
hide: 0,
includeAll: false,
label: 'Latency metrics',
multi: false,
name: 'latency_metrics',
query: 'native : -1,classic : 1',
options: [
{
selected: false,
text: 'native',
value: '-1',
},
{
selected: true,
text: 'classic',
value: '1',
},
],
skipUrlSync: false,
type: 'custom',
useTags: false,
}],
},
},

dashboardLinkUrl(title, url):: self {
links+: [
{
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87 changes: 87 additions & 0 deletions mixin-utils/utils.libsonnet
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Original file line number Diff line number Diff line change
@@ -1,6 +1,93 @@
local g = import 'grafana-builder/grafana.libsonnet';

{
// The classicNativeHistogramQuantile function is used to calculate histogram quantiles from native histograms or classic histograms.
// Metric name should be provided without _bucket suffix.
nativeClassicHistogramQuantile(percentile, metric, selector, sum_by=[], rate_interval='$__rate_interval', multiplier='')::
local classicSumBy = if std.length(sum_by) > 0 then ' by (%(lbls)s) ' % { lbls: std.join(',', ['le'] + sum_by) } else ' by (le) ';
local nativeSumBy = if std.length(sum_by) > 0 then ' by (%(lbls)s) ' % { lbls: std.join(',', sum_by) } else ' ';
local multiplierStr = if multiplier == '' then '' else ' * %s' % multiplier;
{
classic: 'histogram_quantile(%(percentile)s, sum%(classicSumBy)s(rate(%(metric)s_bucket{%(selector)s}[%(rateInterval)s])))%(multiplierStr)s' % {
classicSumBy: classicSumBy,
metric: metric,
multiplierStr: multiplierStr,
percentile: percentile,
rateInterval: rate_interval,
selector: selector,
},
native: 'histogram_quantile(%(percentile)s, sum%(nativeSumBy)s(rate(%(metric)s{%(selector)s}[%(rateInterval)s])))%(multiplierStr)s' % {
metric: metric,
multiplierStr: multiplierStr,
nativeSumBy: nativeSumBy,
percentile: percentile,
rateInterval: rate_interval,
selector: selector,
},
},

// The classicNativeHistogramSumRate function is used to calculate the histogram sum of rate from native histograms or classic histograms.
// Metric name should be provided without _sum suffix.
nativeClassicHistogramSumRate(metric, selector, rate_interval='$__rate_interval')::
{
classic: 'rate(%(metric)s_sum{%(selector)s}[%(rateInterval)s])' % {
metric: metric,
rateInterval: rate_interval,
selector: selector,
},
native: 'histogram_sum(rate(%(metric)s{%(selector)s}[%(rateInterval)s]))' % {
metric: metric,
rateInterval: rate_interval,
selector: selector,
},
},


// The classicNativeHistogramCountRate function is used to calculate the histogram count of rate from native histograms or classic histograms.
// Metric name should be provided without _count suffix.
nativeClassicHistogramCountRate(metric, selector, rate_interval='$__rate_interval')::
{
classic: 'rate(%(metric)s_count{%(selector)s}[%(rateInterval)s])' % {
metric: metric,
rateInterval: rate_interval,
selector: selector,
},
native: 'histogram_count(rate(%(metric)s{%(selector)s}[%(rateInterval)s]))' % {
metric: metric,
rateInterval: rate_interval,
selector: selector,
},
},

// TODO(krajorama) Switch to histogram_avg function for native histograms later.
nativeClassicHistogramAverageRate(metric, selector, rate_interval='$__rate_interval', multiplier='')::
local multiplierStr = if multiplier == '' then '' else '%s * ' % multiplier;
{
classic: |||
%(multiplier)ssum(%(sumMetricQuery)s) /
sum(%(countMetricQuery)s)
||| % {
sumMetricQuery: $.nativeClassicHistogramSumRate(metric, selector, rate_interval).classic,
countMetricQuery: $.nativeClassicHistogramCountRate(metric, selector, rate_interval).classic,
multiplier: multiplierStr,
},
native: |||
%(multiplier)ssum(%(sumMetricQuery)s) /
sum(%(countMetricQuery)s)
||| % {
sumMetricQuery: $.nativeClassicHistogramSumRate(metric, selector, rate_interval).native,
countMetricQuery: $.nativeClassicHistogramCountRate(metric, selector, rate_interval).native,
multiplier: multiplierStr,
},
},

// showClassicHistogramQuery wraps a query defined as map {classic: q, native: q}, and compares the classic query
// to dashboard variable which should take -1 or +1 as values in order to hide or show the classic query.
showClassicHistogramQuery(query, dashboard_variable='latency_metrics'):: '%s < ($%s * +Inf)' % [query.classic, dashboard_variable],
// showNativeHistogramQuery wraps a query defined as map {classic: q, native: q}, and compares the native query
// to dashboard variable which should take -1 or +1 as values in order to show or hide the native query.
showNativeHistogramQuery(query, dashboard_variable='latency_metrics'):: '%s < ($%s * -Inf)' % [query.native, dashboard_variable],
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If I understand correctly, with this utility function, Grafana would always run all the (possibly very expensive) queries, only to get an empty result in one of the cases. (Remember, the PromQL engine doesn't do any smart moves to short-cut evaluations that can never ever return anything.)

Isn't there a Grafana nob we can turn here? Like switching off and on the query on the Grafana level?

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Unfortunately there's no Grafana nob at the moment. So the alternative is to optimize away the query or try to get Grafana to implement something. Both seems like a kind of optimization to be honest.

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Yes, sure, this is just about optimization. I was just hoping there is a simple way of accomplishing it.


histogramRules(metric, labels, interval='1m', record_native=false)::
local vars = {
metric: metric,
Expand Down