for Beginners
Python virtual environment for Beginners
A virtual environment is a tool that helps to keep dependencies required by different projects separate by creating isolated python virtual environments for them. This is one of the most important tools that most of the Python developers use.
When embarking on a DevOps journey, getting a consistent development environment is key. In this post, I show how to setup a virtual environment and install the correct libraries necessary for a project.
Virtual Environments: VirtualEnv
A Virtual Environment is a tool to keep the dependencies required by different projects in separate places, by creating virtual Python environments for them.
The tool in python is called virtualenv
.
To work with isolated environments, you need to follow these steps:
Initial Setup
Install the
virtualenv
tool.Initialize your environment.
Install dependencies.
Create the requirements.txt to remember the dependencies.
Check-in code and the requirements.txt file to code repository.
Developer Installs
Get the latest code.
Install virtual environment.
Install dependencies.
Start working on code.
Let’s look into the steps in detail.
Initial Setup
Before commencing the project, one of the developers can follow these steps to help get the team going. The first step is to install the virtualenv
tool.
The next step is to initialize virtual environment on the project folder.
This step will install python, pip and basic libraries within the project folder, myproject. After version 1.7 of virtualenv, it will use the option –no-site-packages by default. It means that virtualenv will NOT install the libraries available globally. This will help ensure that the project package will contain the bare minimum libraries and the libraries installed for the specific project.
After this, you will need to activate the virtual environment to start working on the project.
Once you do this, your prompt will change to show that you are now working in a virtual environment. It should look something like this:
Now, go ahead and install the libraries that may be required for the project. If all the dependencies can be named at this stage, it will simply make it easier to replicate the environment. The dependency list can always be updated, as I’ll show later.
Once done with the installations, create a list of the libraries and their versions.
This file requirements.txt will hold the necessary dependencies for your project. In one of my projects, it looks like this:
This file will need to be checked in to your project code. At any time, if any other developer installs a new library, it will have to be added to this requirements.txt file. That way, once other developers pull the update from the source code repository, they will be made aware of the new dependencies.
Developer Install
For each developer, the project setup is now straight-forward. They will need to install virtualenv
.
Then, create a folder and activate virtual environment.
After this, they’ll need to check-out the code from the code repository. Assuming it is a Git repo, this will just be a git clone
command.
Now navigate to this sub-folder:
Install the dependencies:
That’s it! Your developer machine is now all set for coding.
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