diff --git a/src/lib/config-utils.js b/src/lib/config-utils.js
index 409a5169c..0a9c38a22 100644
--- a/src/lib/config-utils.js
+++ b/src/lib/config-utils.js
@@ -5,6 +5,14 @@ import minimatch from 'minimatch';
 import assert from 'assert';
 import {ErrorCode} from './utils';
 
+const BLACKLIST = {
+  all: true,
+  anonymous: true,
+  undefined: true,
+  owner: true,
+  none: true,
+};
+
 /**
  * Normalise user list.
  * @return {Array}
@@ -41,6 +49,45 @@ export function getMatchedPackagesSpec(packages: any, pkg: any) {
   return {};
 }
 
+export function uplinkSanityCheck(uplinks: any, users: any = BLACKLIST) {
+  const newUplinks = _.clone(uplinks);
+  let newUsers = _.clone(users);
+
+  for (let uplink in newUplinks) {
+    if (Object.prototype.hasOwnProperty.call(newUplinks, uplink)) {
+      if (_.isNil(newUplinks[uplink].cache)) {
+        newUplinks[uplink].cache = true;
+      }
+      newUsers = sanityCheckNames(uplink, newUsers);
+    }
+  }
+
+  return newUplinks;
+}
+
+export function sanityCheckNames(item: string, users: any) {
+  assert(item !== 'all' && item !== 'owner' && item !== 'anonymous' && item !== 'undefined' && item !== 'none', 'CONFIG: reserved user/uplink name: ' + item);
+  assert(!item.match(/\s/), 'CONFIG: invalid user name: ' + item);
+  assert(users[item] == null, 'CONFIG: duplicate user/uplink name: ' + item);
+  users[item] = true;
+
+  return users;
+}
+
+export function sanityCheckUplinksProps(configUpLinks: any) {
+  const uplinks = _.clone(configUpLinks);
+
+  for (let uplink in uplinks) {
+    if (Object.prototype.hasOwnProperty.call(uplinks, uplink)) {
+      assert(uplinks[uplink].url, 'CONFIG: no url for uplink: ' + uplink);
+      assert( _.isString(uplinks[uplink].url), 'CONFIG: wrong url format for uplink: ' + uplink);
+      uplinks[uplink].url = uplinks[uplink].url.replace(/\/$/, '');
+    }
+  }
+
+  return uplinks;
+}
+
 export function normalisePackageAccess(packages: any): any {
   const normalizedPkgs: any = {...packages};
   // add a default rule for all packages to make writing plugins easier
diff --git a/src/lib/config.js b/src/lib/config.js
index 43027eb50..0501a61cc 100644
--- a/src/lib/config.js
+++ b/src/lib/config.js
@@ -1,42 +1,23 @@
+import _ from 'lodash';
+import assert from 'assert';
+import minimatch from 'minimatch';
+
 import {generateRandomHexString} from './crypto-utils';
-import {normalisePackageAccess} from './config-utils';
-import {getUserAgent} from './utils';
+import {normalisePackageAccess, sanityCheckUplinksProps, uplinkSanityCheck} from './config-utils';
+import {getUserAgent, isObject} from './utils';
 import {APP_ERROR} from './constants';
 
-const assert = require('assert');
-const _ = require('lodash');
-const minimatch = require('minimatch');
-
-const Utils = require('./utils');
 const LoggerApi = require('./logger');
-const strategicConfigProps = ['users', 'uplinks', 'packages'];
+const strategicConfigProps = ['uplinks', 'packages'];
 const allowedEnvConfig = ['http_proxy', 'https_proxy', 'no_proxy'];
 
-function checkUserOrUplink(item, users) {
-  assert(item !== 'all' && item !== 'owner'
-    && item !== 'anonymous' && item !== 'undefined' && item !== 'none', 'CONFIG: reserved user/uplink name: ' + item);
-  assert(!item.match(/\s/), 'CONFIG: invalid user name: ' + item);
-  assert(users[item] == null, 'CONFIG: duplicate user/uplink name: ' + item);
-  users[item] = true;
-}
-
 /**
  * Coordinates the application configuration
  */
 class Config {
-  /**
-   * @param {*} config config the content
-   */
   constructor(config) {
     const self = this;
     this.logger = LoggerApi.logger;
-    const users = {
-      all: true,
-      anonymous: true,
-      undefined: true,
-      owner: true,
-      none: true,
-    };
 
     for (let configProp in config) {
       if (self[configProp] == null) {
@@ -56,41 +37,18 @@ class Config {
       if (self[x] == null) {
         self[x] = {};
       }
-      assert(Utils.isObject(self[x]), `CONFIG: bad "${x}" value (object expected)`);
+
+      assert(isObject(self[x]), `CONFIG: bad "${x}" value (object expected)`);
     });
 
-    // sanity check for users
-    for (let i in self.users) {
-      if (Object.prototype.hasOwnProperty.call(self.users, i)) {
-        checkUserOrUplink(i, users);
-      }
-    }
-    // sanity check for uplinks
-    /* eslint guard-for-in: 0 */
-    for (let i in self.uplinks) {
-      if (self.uplinks[i].cache == null) {
-        self.uplinks[i].cache = true;
-      }
-      if (Object.prototype.hasOwnProperty.call(self.uplinks, i)) {
-        checkUserOrUplink(i, users);
-      }
-    }
+    this.uplinks = sanityCheckUplinksProps(uplinkSanityCheck(this.uplinks));
 
     if (_.isNil(this.users) === false) {
       this.logger.warn(`[users]: property on configuration file 
       is not longer supported, property being ignored`);
     }
 
-    for (let uplink in self.uplinks) {
-      if (Object.prototype.hasOwnProperty.call(self.uplinks, uplink)) {
-        assert(self.uplinks[uplink].url, 'CONFIG: no url for uplink: ' + uplink);
-        assert( typeof(self.uplinks[uplink].url) === 'string'
-          , 'CONFIG: wrong url format for uplink: ' + uplink);
-        self.uplinks[uplink].url = self.uplinks[uplink].url.replace(/\/$/, '');
-      }
-    }
-
-    self.packages = normalisePackageAccess(self.packages);
+    this.packages = normalisePackageAccess(self.packages);
 
     // loading these from ENV if aren't in config
     allowedEnvConfig.forEach((function(v) {
@@ -100,8 +58,8 @@ class Config {
     }));
 
     // unique identifier of self server (or a cluster), used to avoid loops
-    if (!self.server_id) {
-      self.server_id = generateRandomHexString(6);
+    if (!this.server_id) {
+      this.server_id = generateRandomHexString(6);
     }
   }