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This video will walk you through the creation of a virtual environment using venv and explore specific commands used in the process. You’ll also learn how to activate and deactivate a virtual environment in both macOS and Windows.
Resources
Commands
To create a Python virtual environment
-
python3 -m venv myapp-env(macOS) -
python -m venv myapp-env(Windows)
To activate a virtual environment
-
source myapp-env/bin/activate(macOS) -
myapp-env\Scripts\activate(Windows)
To deactivate a virtual environment
deactivate
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Virtual environments are maintained using
tools like virtualenv, venv and conda.
0:00
For this workshop,
we'll be learning and using venv,
0:07
the virtual environment manager that comes
built in with your Python installation.
0:11
Start by downloading the project files and
unzipping the contents.
0:16
You should have one folder named
myapp that contains one file, app.py.
0:22
This file will try to import Flask and
SQLAlchemy and
0:28
then print a message to say
if it was successful or not.
0:32
Don't worry if you're unfamiliar
with these libraries or this code,
0:36
we'll only be using them to test
if the libraries are installed.
0:40
For this workshop, I'll be placing
the myapp folder onto my desktop.
0:44
So I suggest doing the same if
you'd like to follow along.
0:50
Let's open Terminal on macOS or
command prompt on Windows.
0:54
We'll be using the command line for
this workshop.
0:59
But I'll provide the commands as we go, so
1:02
you'll be able to follow along even with
limited knowledge of the command line.
1:05
I'll be using commands for macOS but
if it's different on Windows,
1:10
I'll put the equivalent on the screen and
in the teacher's notes below.
1:14
By default,
terminal will open your user folder.
1:19
So type cd Desktop to
get to the desktop and
1:22
then cd myapp to enter our project folder.
1:27
Let's check out the contents
of this folder by typing ls.
1:31
We can see that we only have
the app.py file provided.
1:36
Before we do anything else let's try
running the app with python3 app.py.
1:41
We can see our app's message saying that
Flask and SQLAlchemy are not installed.
1:49
Let's fix that.
1:55
First, we'll create a virtual environment.
1:57
Type the command python3 -m venv
2:01
myapp-env and press Enter.
2:06
Let's break down
the command we just typed.
2:11
python3 is what activates Python.
2:14
Just like we would type
python3 app.py to run app.py.
2:18
-m is a flag that tells Python to
2:24
run the default file of whatever
library gets called next.
2:27
We don't need to fully understand this
in our current level of learning.
2:32
But just know that this is required
to create a virtual environment.
2:36
venv is the built-in virtual
environment library that
2:41
we're calling to create
a new virtual environment.
2:45
myapp-env is the name I've given
this virtual environment and
2:49
you can name this however you want.
2:54
This comes down to personal preference but
2:56
I suggest picking a naming
convention to stick to.
2:59
If you are following
a course like you are now,
3:03
I suggest using the same name as
the teacher so you don't get confused.
3:06
It may not look like much has happened but
3:12
let's have a look at the contents
of our myapp folder now with ls.
3:15
We can see that myapp-env
folder has been created and
3:21
it's sitting in the same folder as app.py.
3:26
This folder contains everything
needed to run a virtual environment.
3:30
So let's see it in action.
3:35
Type source myapp-env/bin/activate and
press Enter.
3:38
Let's break down the command,
starting with the macOS command.
3:49
source is a command that executes
the contents of the file passed in next.
3:54
myapp-env/bin/activate is
the file that we are executing.
4:01
This is a script that activates
the myapp-env virtual environment.
4:07
Now, for the Windows command,
4:13
myapp-env\Scripts\activate is
an executable file
4:16
that activates the myapp-env
virtual environment.
4:22
Both of these commands execute a script
that will activate our virtual
4:27
environment.
4:31
Remember, myapp-env is just the name that
we've given our virtual environment.
4:32
If you've given your virtual
environment another name,
4:39
it should be used here instead.
4:43
You can now see that your command
line is prefixed by a myapp-env.
4:45
This means that we are now running
inside that virtual environment or
4:52
that little computer,
we talked about in the first video.
4:56
To exit your virtual environment,
simply use the command deactivate.
5:00
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