Adds deprecator (#7303)

* adds deprecator

* un-fit

* added changelog entry

* some fixes

* un-fit

* removed deprecation definition

* changed deprecation log syntax according to Nodejs

src/Deprecator/Deprecations.js

@@ -0,0 +1,14 @@
+/**
+ * The deprecations.
+ *
+ * Add deprecations to the array using the following keys:
+ * - `optionKey`: The option key incl. its path, e.g. `security.enableCheck`.
+ * - `envKey`: The environment key, e.g. `PARSE_SERVER_SECURITY`.
+ * - `changeNewKey`: Set the new key name if the current key will be replaced,
+ * or set to an empty string if the current key will be removed without replacement.
+ * - `changeNewDefault`: Set the new default value if the key's default value
+ * will change in a future version.
+ *
+ * If there are no deprecations this must return an empty array anyway.
+ */
+module.exports = [];

src/Deprecator/Deprecator.js

@@ -0,0 +1,71 @@
+import logger from '../logger';
+import Deprecations from './Deprecations';
+
+/**
+ * The deprecator class.
+ */
+class Deprecator {
+  /**
+   * Scans the Parse Server for deprecated options.
+   * This needs to be called before setting option defaults, otherwise it
+   * becomes indistinguishable whether an option has been set manually or
+   * by default.
+   * @param {any} options The Parse Server options.
+   */
+  static scanParseServerOptions(options) {
+    // Scan for deprecations
+    for (const deprecation of Deprecator._getDeprecations()) {
+      // Get deprecation properties
+      const optionKey = deprecation.optionKey;
+      const changeNewDefault = deprecation.changeNewDefault;
+
+      // If default will change, only throw a warning if option is not set
+      if (changeNewDefault != null && options[optionKey] == null) {
+        Deprecator._log({ optionKey, changeNewDefault });
+      }
+    }
+  }
+
+  /**
+   * Returns the deprecation definitions.
+   * @returns {Array<Object>} The deprecations.
+   */
+  static _getDeprecations() {
+    return Deprecations;
+  }
+
+  /**
+   * Logs a deprecation warning for a Parse Server option.
+   * @param {String} optionKey The option key incl. its path, e.g. `security.enableCheck`.
+   * @param {String} envKey The environment key, e.g. `PARSE_SERVER_SECURITY`.
+   * @param {String} changeNewKey Set the new key name if the current key will be replaced,
+   * or set to an empty string if the current key will be removed without replacement.
+   * @param {String} changeNewDefault Set the new default value if the key's default value
+   * will change in a future version.
+   * @param {String} [solution] The instruction to resolve this deprecation warning. This
+   * message must not include the warning that the parameter is deprecated, that is
+   * automatically added to the message. It should only contain the instruction on how
+   * to resolve this warning.
+   */
+  static _log({ optionKey, envKey, changeNewKey, changeNewDefault, solution }) {
+    const type = optionKey ? 'option' : 'environment key';
+    const key = optionKey ? optionKey : envKey;
+    const keyAction =
+      changeNewKey == null
+        ? undefined
+        : changeNewKey.length > 0
+          ? `renamed to '${changeNewKey}'`
+          : `removed`;
+
+    // Compose message
+    let output = `DeprecationWarning: The Parse Server ${type} '${key}' `;
+    output += changeNewKey ? `is deprecated and will be ${keyAction} in a future version.` : '';
+    output += changeNewDefault
+      ? `default will change to '${changeNewDefault}' in a future version.`
+      : '';
+    output += solution ? ` ${solution}` : '';
+    logger.warn(output);
+  }
+}
+
+module.exports = Deprecator;