Added humanizePercentage formatting to templates (prometheus#5670)

Lots of alerts are based on ratios (eg. disk usage), and humans are used to values in percentage in textual descriptions. Signed-off-by: Jens Erat <email@jenserat.de>
kiranmeduri · Jun 15, 2019 · 375aeb9 · 375aeb9
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diff --git a/console_libraries/prom.lib b/console_libraries/prom.lib
@@ -36,6 +36,7 @@ var PATH_PREFIX = "{{ pathPrefix }}";
 {{ define "humanizeNoSmallPrefix" }}{{ if and (lt . 1.0) (gt . -1.0) }}{{ printf "%.3g" . }}{{ else }}{{ humanize . }}{{ end }}{{ end }}
 {{ define "humanize1024" }}{{ humanize1024 . }}{{ end }}
 {{ define "humanizeDuration" }}{{ humanizeDuration . }}{{ end }}
+{{ define "humanizePercentage" }}{{ humanizePercentage . }}{{ end }}
 {{ define "humanizeTimestamp" }}{{ humanizeTimestamp . }}{{ end }}
 {{ define "printf.1f" }}{{ printf "%.1f" . }}{{ end }}
 {{ define "printf.3g" }}{{ printf "%.3g" . }}{{ end }}

diff --git a/docs/configuration/template_reference.md b/docs/configuration/template_reference.md
@@ -56,6 +56,7 @@ If functions are used in a pipeline, the pipeline value is passed as the last ar
 | humanize      | number        | string  | Converts a number to a more readable format, using [metric prefixes](https://en.wikipedia.org/wiki/Metric_prefix).
 | humanize1024  | number        | string  | Like `humanize`, but uses 1024 as the base rather than 1000. |
 | humanizeDuration | number     | string  | Converts a duration in seconds to a more readable format. |
+| humanizePercentage | number   | string  | Converts a ratio value to a fraction of 100. |
 | humanizeTimestamp | number    | string  | Converts a Unix timestamp in seconds to a more readable format. |
 
 Humanizing functions are intended to produce reasonable output for consumption

diff --git a/template/template.go b/template/template.go
@@ -243,6 +243,9 @@ func NewTemplateExpander(
 				}
 				return fmt.Sprintf("%.4g%ss", v, prefix)
 			},
+			"humanizePercentage": func(v float64) string {
+				return fmt.Sprintf("%.4g%%", v*100)
+			},
 			"humanizeTimestamp": func(v float64) string {
 				if math.IsNaN(v) || math.IsInf(v, 0) {
 					return fmt.Sprintf("%.4g", v)

diff --git a/template/template_test.go b/template/template_test.go
@@ -197,6 +197,11 @@ func TestTemplateExpansion(t *testing.T) {
 			input:  []float64{math.Inf(1), math.Inf(-1), math.NaN()},
 			output: "+Inf:+Inf:+Inf:+Inf:-Inf:-Inf:-Inf:-Inf:NaN:NaN:NaN:NaN:",
 		},
+		{
+			// HumanizePercentage - model.SampleValue input.
+			text:   "{{ -0.22222 | humanizePercentage }}:{{ 0.0 | humanizePercentage }}:{{ 0.1234567 | humanizePercentage }}:{{ 1.23456 | humanizePercentage }}",
+			output: "-22.22%:0%:12.35%:123.5%",
+		},
 		{
 			// HumanizeTimestamp - model.SampleValue input.
 			text:   "{{ 1435065584.128 | humanizeTimestamp }}",