Make literal $ character work in set $location_path

internal/ingress/controller/template/template.go

@@ -120,6 +120,7 @@ var (
 			}
 			return true
 		},
+		"escapeLocationPathVar":      escapeLocationPathVar,
 		"shouldConfigureLuaRestyWAF": shouldConfigureLuaRestyWAF,
 		"buildLuaSharedDictionaries": buildLuaSharedDictionaries,
 		"buildLocation":              buildLocation,
@@ -161,6 +162,20 @@ var (
 	}
 )
 
+// escapeLocationPathVar will replace the $ character with ${literal_dollar}
+// which is made to work via the following configuration in the http section of
+// the template:
+// geo $literal_dollar {
+//     default "$";
+// }
+func escapeLocationPathVar(input interface{}) string {
+	inputStr, ok := input.(string)
+	if !ok {
+		return ""
+	}
+	return strings.Replace(inputStr, `$`, `${literal_dollar}`, -1)
+}
+
 // formatIP will wrap IPv6 addresses in [] and return IPv4 addresses
 // without modification. If the input cannot be parsed as an IP address
 // it is returned without modification.

internal/ingress/controller/template/template_test.go

@@ -834,3 +834,16 @@ func TestBuildUpstreamName(t *testing.T) {
 		}
 	}
 }
+
+func TestEscapeLocationPathVar(t *testing.T) {
+	escapedPath := escapeLocationPathVar("/$")
+	expected := "/${literal_dollar}"
+	if escapedPath != expected {
+		t.Errorf("Expected %s but got %s", expected, escapedPath)
+	}
+	escapedPath = escapeLocationPathVar(false)
+	expected = ""
+	if escapedPath != expected {
+		t.Errorf("Expected %s but got %s", expected, escapedPath)
+	}
+}