Fix incorrect log warning when exporting monitoring via HTTP without authentication (#57279)

Author: danhermann

x-pack/plugin/monitoring/src/main/java/org/elasticsearch/xpack/monitoring/exporter/http/HttpExporter.java

@@ -763,9 +763,15 @@ public static List<String> loadSettings(Settings settings) {
      * @throws SettingsException if the username is missing, but a password is supplied
      */
     @Nullable
-    private static CredentialsProvider createCredentialsProvider(final Config config) {
+    // visible for testing
+    static CredentialsProvider createCredentialsProvider(final Config config) {
         final String username = AUTH_USERNAME_SETTING.getConcreteSettingForNamespace(config.name()).get(config.settings());
 
+        if (Strings.isNullOrEmpty(username)) {
+            // nothing to configure; default situation for most users
+            return null;
+        }
+
         final String deprecatedPassword = AUTH_PASSWORD_SETTING.getConcreteSettingForNamespace(config.name()).get(config.settings());
         final SecureString securePassword = SECURE_AUTH_PASSWORDS.get(config.name());
         final String password;

x-pack/plugin/monitoring/src/test/java/org/elasticsearch/xpack/monitoring/exporter/http/HttpExporterTests.java

@@ -5,6 +5,7 @@
  */
 package org.elasticsearch.xpack.monitoring.exporter.http;
 
+import org.apache.http.client.CredentialsProvider;
 import org.apache.http.entity.ContentType;
 import org.apache.http.entity.StringEntity;
 import org.apache.http.nio.conn.ssl.SSLIOSessionStrategy;
@@ -356,6 +357,17 @@ public void testCreateRestClient() throws IOException {
         }
     }
 
+    public void testCreateCredentialsProviderWithoutSecurity() {
+        final Settings.Builder builder = Settings.builder()
+            .put("xpack.monitoring.exporters._http.type", "http")
+            .put("xpack.monitoring.exporters._http.host", "http://localhost:9200");
+
+        final Config config = createConfig(builder.build());
+        CredentialsProvider provider = HttpExporter.createCredentialsProvider(config);
+
+        assertNull(provider);
+    }
+
     public void testCreateSnifferDisabledByDefault() {
         final Config config = createConfig(Settings.EMPTY);
         final RestClient client = mock(RestClient.class);