diff --git a/ee/cli/plugins/stack.py b/ee/cli/plugins/stack.py
index ba6de30e..04e2567f 100644
--- a/ee/cli/plugins/stack.py
+++ b/ee/cli/plugins/stack.py
@@ -7,6 +7,7 @@ from ee.core.aptget import EEAptGet
 from ee.core.download import EEDownload
 from ee.core.shellexec import EEShellExec
 from ee.core.fileutils import EEFileUtils
+from ee.core.apt_repo import EERepo
 from pynginxconfig import NginxConfig
 import random
 import string
@@ -49,16 +50,17 @@ class EEStackController(CementBaseController):
 
     @expose(hide=True)
     def pre_pref(self, apt_packages):
-        if "postfix" in apt_packages:
+        if set(EEVariables.ee_postfix).issubset(set(apt_packages)):
             EEShellExec.cmd_exec("echo \"postfix postfix/main_mailer_type "
                                  "string 'Internet Site'\" | "
                                  "debconf-set-selections")
             EEShellExec.cmd_exec("echo \"postfix postfix/mailname string "
                                  "$(hostname -f)\" | debconf-set-selections")
-        if "mysql" in apt_packages:
-            EERepo.add(repo_url="deb http://repo.percona.com/apt "
+        if set(EEVariables.ee_mysql).issubset(set(apt_packages)):
+            EERepo.add(ppa='deb http://repo.percona.com/apt '
                        + EEVariables.ee_platform_codename + " main")
             EERepo.add_key('hkp://keys.gnupg.net', '1C4CBDCDCD2EFD2A ')
+            
             chars = ''.join(random.sample(string.letters, 8))
             EEShellExec.cmd_exec("echo \"percona-server-server-5.6 "
                                  "percona-server-server/root_password "
@@ -72,11 +74,9 @@ class EEStackController(CementBaseController):
     @expose(hide=True)
     def post_pref(self, apt_packages, packages):
         if len(apt_packages):
-            print("In post")
-            print(apt_packages)
-            if "postfix" in apt_packages:
+            if set(EEVariables.ee_postfix).issubset(set(apt_packages)):
                 pass
-            if 'nginx-custom' in apt_packages:
+            if set(EEVariables.ee_nginx).issubset(set(apt_packages)):
                 # Nginx core configuration change using configparser
                 nc = NginxConfig()
                 print('in nginx')
diff --git a/ee/core/apt_repo.py b/ee/core/apt_repo.py
index 0449a0fc..70b1ef49 100644
--- a/ee/core/apt_repo.py
+++ b/ee/core/apt_repo.py
@@ -1,6 +1,4 @@
-
 import os.path
-import gnupg
 from ee.core.shellexec import EEShellExec
 from ee.core.variables import EEVariables
 
@@ -33,20 +31,20 @@ class EERepo():
                 print("Cannot add repo for {distro}"
                       .format(distro=EEVariables.ee_platform_distro))
             else:
-                EEShellExec.cmd_exec("add-apt-repository -y {ppa_name}"
+                EEShellExec.cmd_exec("add-apt-repository -y '{ppa_name}'"
                                      .format(ppa_name=ppa))
 
     def remove(repo_url=None):
         # TODO remove repository
-        EEShellExec.cmd_exec("add-apt-repository -y"
+        EEShellExec.cmd_exec("add-apt-repository -y "
                              "--remove '{ppa_name}'".format(ppa_name=repo_url))
         pass
 
     def add_key(keyserver, keyids):
-        EEShellExec.cmd_exec("gpg --keyserver  {0}".format(keyserver)
-                             "--recv-keys {0}".format(keyids))
+        EEShellExec.cmd_exec("gpg --keyserver {serv}".format(serv=keyserver)
+                             + " --recv-keys {key}".format(key=keyids))
         EEShellExec.cmd_exec("gpg -a --export --armor {0}".format(keyids)
-                             "| apt-key add - ")
+                             + " | apt-key add - ")
 
 # if __name__ == '__main__':
 #   EERepo().add(repo_url="http://ds.asf", codename="trusty", repo_type="main")