How to Create Virtual Environments in Spack: Isolating Software Environments Made Easy

As of my last update in September 2021, Spack does not natively provide a built-in virtual environment functionality similar to Python's virtualenv or Anaconda environments. However, you can achieve similar isolation and environment management using Spack's environments feature. Spack environments allow you to create isolated environments for specific sets of packages, similar to how virtual environments work.

Here's how you can create a virtual environment-like environment using Spack:

1. Initialize a New Environment:

To start using Spack environments, you need to initialize a new environment:

spack env create <environment_name>

Replace <environment_name> with the desired name for your environment.

2. Activate the Environment:

After creating the environment, activate it to work within the isolated environment:

spack env activate <environment_name>

3. Install Packages in the Environment:

Once your environment is activated, you can use Spack to install packages inside the environment. For example:

spack install <package_name>

This will install the specified package inside the currently activated environment.

4. Deactivate the Environment:

To exit the environment and return to your system's default environment, you can deactivate the Spack environment:

spack env deactivate

5. List Environments:

You can list all available environments and see which one is currently activated using:

spack env list

6. Use a Specific Environment:

To use a specific environment for building, installing, or uninstalling packages, activate it using:

spack env activate <environment_name>

7. Remove an Environment:

To remove an environment and all its installed packages, use:

spack env remove <environment_name>

Remember that Spack environments primarily isolate the build and install operations of packages within each environment, but they do not provide full isolation like virtual environments in Python. If you want complete isolation, consider using a container solution like Docker or Singularity in combination with Spack to achieve similar effects.

As Spack is under active development, please check the official documentation or release notes for any updates on Spack's environment management capabilities beyond my last update.