# Install AWS ParallelCluster in a virtual environment (recommended)
<a name="install-virtualenv"></a>

We recommend that you install AWS ParallelCluster in a virtual environment to avoid requirement version conflicts with other `pip` packages.

**Prerequisites**
+ Verify that `pip` and Python are installed. We recommend `pip3`, and Python 3 version 3.8. If you are using Python 2, use `pip` instead of `pip3` and `virtualenv` instead of `venv`.

**To install AWS ParallelCluster in a virtual environment**

1. If `virtualenv` is not installed, install `virtualenv` using `pip3`. If `python3 -m virtualenv help` displays help information, go to step 2.

------
#### [ Linux, macOS, or Unix ]

   ```
   $ python3 -m pip install --upgrade pip
   $ python3 -m pip install --user --upgrade virtualenv
   ```

   Run `exit` to leave the current terminal window and open a new terminal window to pick up changes to the environment.

------
#### [ Windows ]

   ```
   C:\>pip3 install --user --upgrade virtualenv
   ```

   Run `exit` to leave the current command prompt and open a new command prompt to pick up changes to the environment.

------

1. Create a virtual environment and name it.

------
#### [ Linux, macOS, or Unix ]

   ```
   $ python3 -m virtualenv ~/apc-ve
   ```

   Alternatively, you can use the `-p` option to specify a specific version of Python.

   ```
   $ python3  -m virtualenv -p $(which python3) ~/apc-ve
   ```

------
#### [ Windows ]

   ```
   C:\>virtualenv %USERPROFILE%\apc-ve
   ```

------

1. <a name="activate-virtual-environment"></a>Activate your new virtual environment.

------
#### [ Linux, macOS, or Unix ]

   ```
   $ source ~/apc-ve/bin/activate
   ```

------
#### [ Windows ]

   ```
   C:\>%USERPROFILE%\apc-ve\Scripts\activate
   ```

------

1. Install AWS ParallelCluster into your virtual environment.

------
#### [ Linux, macOS, or Unix ]

   ```
   (apc-ve)~$ python3 -m pip install --upgrade "aws-parallelcluster<3.0"
   ```

------
#### [ Windows ]

   ```
   (apc-ve) C:\>pip3 install --upgrade "aws-parallelcluster<3.0"
   ```

------

1. Verify that AWS ParallelCluster is installed correctly.

------
#### [ Linux, macOS, or Unix ]

   ```
   $ pcluster version
   2.11.9
   ```

------
#### [ Windows ]

   ```
   (apc-ve) C:\>pcluster version
   2.11.9
   ```

------

You can use the `deactivate` command to exit the virtual environment. Each time you start a session, you must [reactivate the environment](#activate-virtual-environment).

To upgrade to the latest version of AWS ParallelCluster, run the installation command again.

------
#### [ Linux, macOS, or Unix ]

```
(apc-ve)~$ python3 -m pip install --upgrade "aws-parallelcluster<3.0"
```

------
#### [ Windows ]

```
(apc-ve) C:\>pip3 install --upgrade "aws-parallelcluster<3.0"
```

------