1 files changed, 51 insertions, 0 deletions
diff --git a/internal/config/multi_string_flag.go b/internal/config/multi_string_flag.go
new file mode 100644
index 00000000..fc63299b
--- /dev/null
+++ b/internal/config/multi_string_flag.go
@@ -0,0 +1,51 @@
+package config
+
+import (
+	"errors"
+	"strings"
+)
+
+var errMultiStringSetEmptyValue = errors.New("value cannot be empty")
+
+const defaultSeparator = ","
+
+// MultiStringFlag implements the flag.Value interface and allows a string flag
+// to be specified multiple times on the command line.
+//
+// e.g.: -listen-http 127.0.0.1:80 -listen-http [::1]:80
+type MultiStringFlag struct {
+	value     []string
+	separator string
+}
+
+// String returns the list of parameters joined with a commas (",")
+func (s *MultiStringFlag) String() string {
+	return strings.Join(s.value, s.sep())
+}
+
+// Set appends the value to the list of parameters
+func (s *MultiStringFlag) Set(value string) error {
+	if value == "" {
+		return errMultiStringSetEmptyValue
+	}
+
+	s.value = append(s.value, value)
+	return nil
+}
+
+// Split each flag
+func (s *MultiStringFlag) Split() (result []string) {
+	for _, str := range s.value {
+		result = append(result, strings.Split(str, s.sep())...)
+	}
+
+	return
+}
+
+func (s *MultiStringFlag) sep() string {
+	if s.separator == "" {
+		return defaultSeparator
+	}
+
+	return s.separator
+}