fix: purge LDAP deprecated keys

cmd/config/identity/ldap/config.go

@@ -103,6 +103,11 @@ const (
 	EnvLookupBindPassword = "MINIO_IDENTITY_LDAP_LOOKUP_BIND_PASSWORD"
 )
 
+var removedKeys = []string{
+	"username_search_filter",
+	"username_search_base_dn",
+}
+
 // DefaultKVS - default config for LDAP config
 var (
 	DefaultKVS = config.KVS{
@@ -366,6 +371,12 @@ func Enabled(kvs config.KVS) bool {
 // Lookup - initializes LDAP config, overrides config, if any ENV values are set.
 func Lookup(kvs config.KVS, rootCAs *x509.CertPool) (l Config, err error) {
 	l = Config{}
+
+	// Purge all removed keys first
+	for _, k := range removedKeys {
+		kvs.Delete(k)
+	}
+
 	if err = config.CheckValidKeys(config.IdentityLDAPSubSys, kvs, DefaultKVS); err != nil {
 		return l, err
 	}