Allow wildcard filtering of varnish stats

closes #1275

internal/internal.go

@@ -16,6 +16,8 @@ import (
 	"strings"
 	"time"
 	"unicode"
+
+	"github.com/gobwas/glob"
 )
 
 const alphanum string = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
@@ -205,3 +207,24 @@ func WaitTimeout(c *exec.Cmd, timeout time.Duration) error {
 		return TimeoutErr
 	}
 }
+
+// CompileFilter takes a list of glob "filters", ie:
+//   ["MAIN.*", "CPU.*", "NET"]
+// and compiles them into a glob object. This glob object can
+// then be used to match keys to the filter.
+func CompileFilter(filters []string) (glob.Glob, error) {
+	var out glob.Glob
+
+	// return if there is nothing to compile
+	if len(filters) == 0 {
+		return out, nil
+	}
+
+	var err error
+	if len(filters) == 1 {
+		out, err = glob.Compile(filters[0])
+	} else {
+		out, err = glob.Compile("{" + strings.Join(filters, ",") + "}")
+	}
+	return out, err
+}