Environments

Environments#

Environments in Spack feel a whole lot like environments in Conda; they allow you to bundle up a number of different pieces of software into a single entity, making a single coherent collection.

This is a very simple introduction, and really doesn’t cover all the things you can do with environments, so if you’re interested in these, please read the main documentation links in the References section.

Creating an environment#

Here’s a minimal workflow for creating an environment:

  • Create a blank environment

    spack env create myenv

  • Activate it

    spack env activate myenv

  • Add a list of software to it

    spack add bash@5 python py-numpy py-scipy py-matplotlib openssl@3.0.7

  • Tweak the config if required

    spack config edit

    Please review the references for more information on options here, but nothing needs changing this time.

  • Validate the installation

    spack concretize

    Concretizing the spec resolves all the dependecies and shows you what Spack believes is required to satisfy you requirements.

  • Build and install the software

    spack install

Note this follows the normal behaviour of Spack, reusing previously built software, and external software you’ve told it to use.

Using an environment#

Again, this feels very familiar to people used to Conda; you have to activate an environment before using it (although we did actually do this earlier when we created it):

spack env activate myenv

Once activated, you can confirm that it’s really live:

$ which bash
~/spack/var/spack/environments/myenv/.spack-env/view/bin/bash
$ bash --version
GNU bash, version 5.3.3(1)-release (x86_64-pc-linux-gnu)
Copyright (C) 2025 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Deactivating an environment#

You can leave an environment using:

spack env deactivate

References#

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