Add parseDuration function to templates

Signed-off-by: Vadim Aleksandrov <valeksandrov@me.com>

docs/notifications.md

@@ -99,3 +99,4 @@ templating.
 | tz | string, time.Time | Returns the time in the timezone. For example, Europe/Paris. |
 | since | time.Time | [time.Duration](https://pkg.go.dev/time#Since), returns the duration of how much time passed from the provided time till the current system time. |
 | humanizeDuration | number or string | Returns a human-readable string representing the duration, and the error if it happened. |
+| parseDuration | string | Returns the time.Duration representation of a passed string. |

template/template.go

@@ -207,6 +207,10 @@ var DefaultFuncs = FuncMap{
 	},
 	"since":            time.Since,
 	"humanizeDuration": commonTemplates.HumanizeDuration,
+	// parseDuration returns the time.Duration representation of a passed string
+	"parseDuration": func(text string) (time.Duration, error) {
+		return time.ParseDuration(text)
+	},
 }
 
 // Pair is a key/value string pair.

template/template_test.go

@@ -561,6 +561,14 @@ func TestTemplateFuncs(t *testing.T) {
 		in:    "{{ . | since | humanizeDuration }}",
 		data:  time.Now().Add(-1 * time.Hour),
 		exp:   "1h 0m 0s",
+	}, {
+		title: "Template using duration",
+		in:    `{{ "60s" | parseDuration | printf "%d" }}`,
+		exp:   "60000000000",
+	}, {
+		title:  "Template using invalid duration",
+		in:     `{{ "60k" | parseDuration | printf "%d" }}`,
+		expErr: "template: :1:11: executing \"\" at <parseDuration>: error calling parseDuration: time: unknown unit \"k\" in duration \"60k\"",
 	}} {
 		tc := tc
 		t.Run(tc.title, func(t *testing.T) {