Update to return a float

Signed-off-by: David Leadbeater <dgl@dgl.cx>

docs/configuration/template_reference.md

@@ -74,7 +74,7 @@ versions.
 | reReplaceAll  | pattern, replacement, text | string | [Regexp.ReplaceAllString](https://golang.org/pkg/regexp/#Regexp.ReplaceAllString) Regexp substitution, unanchored. |
 | graphLink  | expr | string | Returns path to graph view in the [expression browser](https://prometheus.io/docs/visualization/browser/) for the expression. |
 | tableLink  | expr | string | Returns path to tabular ("Table") view in the [expression browser](https://prometheus.io/docs/visualization/browser/) for the expression. |
-| parseDuration | string | string | Parses a duration string such as "1h" into the integer number of seconds it represents. |
+| parseDuration | string | float | Parses a duration string such as "1h" into the number of seconds it represents. |
 
 ### Others
 

template/template.go

@@ -304,13 +304,12 @@ func NewTemplateExpander(
 			"externalURL": func() string {
 				return externalURL.String()
 			},
-			"parseDuration": func(d string) (string, error) {
+			"parseDuration": func(d string) (float64, error) {
 				v, err := model.ParseDuration(d)
 				if err != nil {
-					return "", err
+					return 0, err
 				}
-				dur := int64(time.Duration(v) / time.Second)
-				return fmt.Sprintf("%d", dur), nil
+				return float64(time.Duration(v)) / float64(time.Second), nil
 			},
 		},
 		options: options,

template/template_test.go

@@ -450,9 +450,9 @@ func TestTemplateExpansion(t *testing.T) {
 			output: "http://testhost:9090/path/prefix",
 		},
 		{
-			// parseDuration.
-			text:   "{{ parseDuration \"1h2m10ms\" }}",
-			output: "3720",
+			// parseDuration (using printf to ensure the return is a string).
+			text:   "{{ printf \"%0.2f\" (parseDuration \"1h2m10ms\") }}",
+			output: "3720.01",
 		},
 	}