Log the configs when app starts.

index.js

@@ -3,6 +3,8 @@
  */
 'use strict';
 
+const config = require('config');
+const _ = require('lodash');
 const kafka = require('./utils/kafka');
 const logger = require('./utils/logger');
 
@@ -19,5 +21,38 @@ process.on('unhandledRejection', (err) => {
   logger.logFullError(err, 'system');
 });
 
+// dump the configuration to logger
+const ignoreConfigLog = ['cert', 'key', 'AWS_ACCESS_KEY_ID', 'AWS_SECRET_ACCESS_KEY', 'AUTH0_CLIENT_ID', 'AUTH0_CLIENT_SECRET'];
+/**
+ * Print configs to logger
+ * @param {Object} params the config params
+ * @param {Number} level the level of param object
+ */
+function dumpConfigs(params, level) {
+  Object.keys(params).forEach((key) => {
+    if (_.includes(ignoreConfigLog, key)) {
+      return;
+    }
+    const item = params[key];
+    let str = '';
+    let n = 0;
+    while (n < level) { // eslint-disable-line no-restricted-syntax
+      n++;
+      str += '  ';
+    }
+    if (item && _.isObject(item)) {
+      str += `${key}=`;
+      logger.debug(str);
+      dumpConfigs(item, level + 1);
+    } else {
+      str += `${key}=${item}`;
+      logger.debug(str);
+    }
+  });
+}
+logger.debug('--- List of Configurations ---');
+dumpConfigs(config, 0);
+logger.debug('--- End of List of Configurations ---');
+
 // run the server
 kafka.run();