python virtual environment setup in ubuntu

Python is a open source software. It has thousands of third-party packages developed by developers all over the world. All these packages were maintained by PiPy.

For developing complex application we need to install many third-party libraries based on the requirement. All these packages were installed in system level.
If we are working on two projects in parallel  one project is dependent on python2.7 and other is dependent on python3.5.

After completion of development the installed packages are no more required.
And they may slowdown the working speed of the system. To avoid such conditions we use python virtual environment.

We use system package "python-pip" for virtualenv.

sudo apt-get install python-pip

"virtualenv" is a third-party python package, it provides python virtual environment.

1. Setup virtualenv python

pip install virtualenv
virtualenv project_env
# for python3
virtualenv -p python3 project_env 

2. activate env to use virtualenv

source project_env/bin/activate

3. Install required packages

pip install requests

4. Un-Install packages from env

pip remove requests

5. Get list of all installed packages

pip freeze

6. Save list of required packages with version

pip freeze > requirements.txt

7. Install saved requirements

pip install -r requirements.txt

8. Deactivate the virtualenv when you finish work

deactivate

Advantages using python virtual environment

• We can experiment with new packages
• We can have list of required packages for future reference.
• We can maintain clean technical requirements for project.

Architecture

Virtual environment architecture

 

 pip Python virtualenv