diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index fa7c98178b88a18a39abb9faedf53784a182abad..08a80e10958c2a65fc036db6c119f08bf49efd58 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -94,8 +94,14 @@ deploy-webserver:
     - yum install -y gcc
     - yum install -y https://repo.ius.io/ius-release-el7.rpm
     - yum update -y
-    - yum install -y python35u python35u-libs python35u-devel python35u-pip openssl-devel  libffi-devel
-    - pip3.5 install ansible
+    - yum install -y python36u python36u-libs python36u-devel python36u-pip openssl-devel  libffi-devel
+    - python3.6 -m pip install --upgrade pip
+    - export PYTHONIOENCODING=utf8
+    - export LANG=en_US.UTF-8
+    - export LANGUAGE=en_US:en
+    - export LC_ALL=en_US.UTF-8
+    - python3.6 -m pip install ansible
+    - python3.6 -m pip install virtualenv
     - cd ansible
     - whoami
     - ansible-playbook -vvv -i ./hosts_deploy deploy.yaml --extra-vars "@params-server.json"
diff --git a/ansible/deploy.yaml b/ansible/deploy.yaml
index bcc68ffda797942050ae022d4886fcbf2445a97f..42ecdfc3df963aa2f562c4beb7509f1f385e573d 100644
--- a/ansible/deploy.yaml
+++ b/ansible/deploy.yaml
@@ -61,6 +61,12 @@
     - name: nginx
       become: true
       yum: name=nginx state=latest
+    - name: zlib-devel # required by Pillow
+      become: true
+      yum: name=zlib-devel state=latest
+    - name: libjpeg-turbo-devel # required by Pillow
+      become: true
+      yum: name=libjpeg-turbo-devel state=latest
     - pip: 
         name: wheel
         executable: pip3.6
diff --git a/doc/source/install.rst b/doc/source/install.rst
index 765e11699af4e3c6c114824de7998f67f4507e9d..cf21ea83a1c02ac11c06471f52e9494946206d43 100644
--- a/doc/source/install.rst
+++ b/doc/source/install.rst
@@ -19,6 +19,20 @@ We advise users to install jass in a virtual environment
 Installation with conda
 -----------------------
 
+Installation with pip (recommended)
+-----------------------------------
+We advise users to install jass in a virtual environment
+
+.. code-block:: shell
+
+	python3 -m venv $PATH_NEW_ENVIRONMENT
+	source $PATH_NEW_ENVIRONMENT/bin/activate
+	pip3 install git+https://gitlab.pasteur.fr/statistical-genetics/jass.git
+	pip3 install -r https://gitlab.pasteur.fr/statistical-genetics/jass/-/raw/master/requirements.txt
+
+Installation with conda
+-----------------------
+
 A procedure for the correct installation of JASS in Anaconda environment for development purpose is developed in detail below.
 
 **1. Create a specific directory and load the code on your laptop (only the first time)**
diff --git a/jass/__main__.py b/jass/__main__.py
index 5797104832415ab808d54886eef27731b456cf87..ba864f26cf09900c5d7d446fb468aee4e09df22f 100644
--- a/jass/__main__.py
+++ b/jass/__main__.py
@@ -180,17 +180,15 @@ def w_clean_project_data(args):
 
 def w_create_inittable(args):
     input_data_path = absolute_path_of_the_file(args.input_data_path)
+    init_covariance_path = args.init_covariance_path
+    init_genetic_covariance_path = args.init_genetic_covariance_path
 
     #if genetic and H0 covariance provided search its absolute path
-    if args.init_covariance_path:
-        init_covariance_path = absolute_path_of_the_file(args.init_covariance_path)
-    else:
-        init_covariance_path = args.init_covariance_path
+    if init_covariance_path is not None:
+        init_covariance_path = absolute_path_of_the_file(init_covariance_path)
 
-    if args.init_genetic_covariance_path:
-        init_genetic_covariance_path = absolute_path_of_the_file(args.init_genetic_covariance_path)
-    else:
-        init_genetic_covariance_path = args.init_genetic_covariance_path
+    if init_genetic_covariance_path is not None:
+        init_genetic_covariance_path = absolute_path_of_the_file(init_genetic_covariance_path)
 
     regions_map_path = absolute_path_of_the_file(args.regions_map_path)
     description_file_path = absolute_path_of_the_file(args.description_file_path)
@@ -391,6 +389,7 @@ def get_parser():
     )
     parser_create_it.add_argument(
         "--init-genetic-covariance-path",
+        required=False,
         default=None,
         help="path to the genetic covariance file to import. Used only for display on Jass web application",
     )
diff --git a/setup.py b/setup.py
index f9df3d2ac7745c198d1d2c83ba02f4c93b9babd8..72f3b8f574e21084b65691e90f80448e2a259de8 100644
--- a/setup.py
+++ b/setup.py
@@ -7,7 +7,7 @@ import pkg_resources
 from setuptools import setup, find_packages
 
 NAME = "jass"
-VERSION = "2.1"
+VERSION = "2.2"
 
 SETUP_DIR = os.path.dirname(__file__)
 README = os.path.join(SETUP_DIR, 'README.md')