cmd/bosun: add pct template function

cmd/bosun/conf/conf.go

@@ -668,10 +668,13 @@ var defaultFuncs = ttemplate.FuncMap{
 		}
 		return ByteSize(0), fmt.Errorf("unexpected type: %T (%v)", v, v)
 	},
+	"pct": func(i interface{}) string {
+		return fmt.Sprintf("%.2f%%", i)
+	},
+	"replace": strings.Replace,
 	"short": func(v string) string {
 		return strings.SplitN(v, ".", 2)[0]
 	},
-	"replace": strings.Replace,
 }
 
 func (c *Conf) loadTemplate(s *parse.SectionNode) {

docs/configuration.md

@@ -144,6 +144,7 @@ Global template functions:
 
 * V: performs variable expansion on the argument and returns it. Needed since normal variable expansion is not done due to the `$` character being used by the Go template syntax.
 * bytes: converts the string input into a human-readable number of bytes with extension KB, MB, GB, etc.
+* pct: formats the float argument as a percentage. For example: `{{5.1 | pct}}` -> `5.10%`.
 * replace: [strings.Replace](http://golang.org/pkg/strings/#Replace)
 * short: Trims the string to everything before the first period. Useful for turning a FQDN into a shortname. For example: `{{short "foo.baz.com"}}` -> `foo`.