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diff --git a/posts/2014-11-08-reproducible-development-environments.md b/posts/2014-11-08-reproducible-development-environments.md new file mode 100644 index 0000000..1672c78 --- /dev/null +++ b/posts/2014-11-08-reproducible-development-environments.md @@ -0,0 +1,120 @@ +title: Reproducible Development Environments with GNU Guix +date: 2014-11-08 22:00 +tags: gnu, guix, scheme, guile, wsu +summary: Easily acquire the dependencies needed to hack on a project +--- + +If you’re a software developer, then you probably know very well that +setting up a project’s development environment for the first time can +be a real pain. Installing all of the necessary dependencies using +your system’s package manager can be very tedious. To "solve" this +problem, we have resorted to inventing new package managers and +dependency bundlers for pretty much every programming language. Ruby +has rubygems and bundler, Python has pip and virtualenv, PHP has +composer, node.js has npm, and so on. Wouldn’t it be nice to instead +have a single package manager that can handle it all? Enter +[GNU Guix](https://gnu.org/s/guix), a purely functional package +manager and GNU/Linux distribution. Using Guix, you can easily create +a development environment for any software project using the `guix +environment` tool. + +`guix environment` is a new utility added in Guix 0.8, which should be +released in a few weeks. It accepts one or more packages as input and +produces a new shell environment in which all of the dependencies for +those packages are made available. For example, `guix environment +emacs` will get you everything you need to build GNU Emacs from a +source release tarball. By default, your `$SHELL` is spawned, but +you may opt to use any arbitrary shell command instead. If you’ve +used Nix before, you may notice that this sounds exactly like +`nix-shell`, and that’s because it was what inspired me to write +`guix environment`. + +Now, let’s take a look at an example. One of my hobby projects is +[Sly](https://gitorious.org/sly/sly), a game engine written in Guile +Scheme. Here’s the relevant Guix code that will produce a complete +development environment: + +```scheme + + ;;; Copyright (C) 2014 David Thompson <davet@gnu.org> + ;;; + ;;; Sly is free software: you can redistribute it and/or modify it + ;;; under the terms of the GNU General Public License as published by + ;;; the Free Software Foundation, either version 3 of the License, or + ;;; (at your option) any later version. + + (use-modules (guix packages) + (guix licenses) + (guix build-system gnu) + (gnu packages) + (gnu packages autotools) + (gnu packages guile) + (gnu packages gl) + (gnu packages pkg-config) + (gnu packages sdl) + (gnu packages maths) + (gnu packages image)) + + ;; The development environment needs a tweaked LTDL_LIBRARY_PATH + ;; for finding libfreeimage. + (define freeimage + (package (inherit freeimage) + (native-search-paths + (list (search-path-specification + (variable "LTDL_LIBRARY_PATH") + (directories '("lib"))))))) + + (package + (name "sly") + (version "0.0") + (source #f) + (build-system gnu-build-system) + (inputs + `(("pkg-config" ,pkg-config) + ("autoconf" ,autoconf) + ("automake" ,automake) + ("guile" ,guile-2.0) + ("guile-sdl" ,guile-sdl) + ("guile-opengl" ,guile-opengl) + ("gsl" ,gsl) + ("freeimage" ,freeimage) + ("mesa" ,mesa))) + (synopsis "2D/3D game engine for GNU Guile") + (description "Sly is a 2D/3D game engine written in Guile Scheme. + Sly differs from most game engines in that it emphasizes functional + reactive programming and live coding.") + (home-page "https://gitorious.org/sly/sly") + (license gpl3+)) +``` + +You may have noticed that the source field has been set to false. +This is because the package is not for building and installing. It’s +sole purpose is to provide the necessary software needed to build Sly +from a fresh git checkout. + +Assuming this code is in a file called `package.scm`, you can simply +run `guix environment -l package.scm` to spawn a shell for hacking +on Sly. By default, the environment created is an augmented version +of your pre-existing shell’s environment. This is convenient when you +want to use your installed software in the new environment, such as +git. However, it’s important to make sure that the environment really +does have everything needed for development without relying on any +impurities introduced by your existing environment. Without verifying +this, new developers might be frustrated to find out that the +environment provided to them is incomplete. To verify, pass the +`--pure` flag and build from scratch. + +So, `guix environment` is a pretty nice way to acquire all the +dependencies you need to work on a project, but there is still a lot +of room for improvement. What if you were working on a web +application that required a running PostgreSQL database, Redis server, +and XMPP server? It would be really great if Guix could handle +setting this up for you, too, a la Vagrant. To do so, `guix +environment` could use the existing features of `guix system` to spawn +a new virtual machine that shares the host system’s package store and +the project’s source tree, and then spawn a shell with your +development environment. I hope to implement this in the +not-too-distant future. Until next time, happy hacking! + +Read the discussion about this post on +[Hacker News](https://news.ycombinator.com/item?id=8616918). |