Better parsing of regex replacements

parser/parser.go

@@ -43,26 +43,34 @@ type ConfigurationFile struct {
 // Defines a single find/replace instance for a given server configuration file.
 type ConfigurationFileReplacement struct {
 	Match       string       `json:"match"`
-	IfValue     *string      `json:"if_value"`
+	IfValue     string       `json:"if_value"`
 	ReplaceWith ReplaceValue `json:"replace_with"`
 }
 
 // Handles unmarshaling the JSON representation into a struct that provides more useful
 // data to this functionality.
 func (cfr *ConfigurationFileReplacement) UnmarshalJSON(data []byte) error {
-	if m, err := jsonparser.GetString(data, "match"); err != nil {
-		return err
-	} else {
-		cfr.Match = m
+	m, err := jsonparser.GetString(data, "match")
+	if err != nil {
+		return errors.WithStack(err)
 	}
+	cfr.Match = m
 
-	if v, dt, _, err := jsonparser.Get(data, "replace_with"); err != nil {
-		return err
-	} else {
-		cfr.ReplaceWith = ReplaceValue{
-			value:     v,
-			valueType: dt,
-		}
+	iv, err := jsonparser.GetString(data, "if_value")
+	// We only check keypath here since match & replace_with should be present on all of
+	// them, however if_value is optional.
+	if err != nil && err != jsonparser.KeyPathNotFoundError {
+		return errors.WithStack(err)
+	}
+	cfr.IfValue = iv
+
+	rw, dt, _, err := jsonparser.Get(data, "replace_with")
+	if err != nil {
+		return errors.WithStack(err)
+	}
+	cfr.ReplaceWith = ReplaceValue{
+		value:     rw,
+		valueType: dt,
 	}
 
 	return nil
@@ -370,7 +378,7 @@ func (f *ConfigurationFile) parsePropertiesFile(path string) error {
 		// Don't attempt to replace the value if we're looking for a specific value and
 		// it does not match. If there was no match at all in the file for this key but
 		// we're doing an IfValue match, do nothing.
-		if replace.IfValue != nil && (!ok || (ok && v != *replace.IfValue)) {
+		if replace.IfValue != "" && (!ok || (ok && v != replace.IfValue)) {
 			continue
 		}