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diff --git a/doc/builders/special/fhs-environments.section.md b/doc/builders/special/fhs-environments.section.md new file mode 100644 index 00000000000..cacad261e28 --- /dev/null +++ b/doc/builders/special/fhs-environments.section.md @@ -0,0 +1,49 @@ +# buildFHSUserEnv {#sec-fhs-environments} + +`buildFHSUserEnv` provides a way to build and run FHS-compatible lightweight sandboxes. It creates an isolated root with bound `/nix/store`, so its footprint in terms of disk space needed is quite small. This allows one to run software which is hard or unfeasible to patch for NixOS -- 3rd-party source trees with FHS assumptions, games distributed as tarballs, software with integrity checking and/or external self-updated binaries. It uses Linux namespaces feature to create temporary lightweight environments which are destroyed after all child processes exit, without root user rights requirement. Accepted arguments are: + +- `name` + Environment name. +- `targetPkgs` + Packages to be installed for the main host's architecture (i.e. x86_64 on x86_64 installations). Along with libraries binaries are also installed. +- `multiPkgs` + Packages to be installed for all architectures supported by a host (i.e. i686 and x86_64 on x86_64 installations). Only libraries are installed by default. +- `extraBuildCommands` + Additional commands to be executed for finalizing the directory structure. +- `extraBuildCommandsMulti` + Like `extraBuildCommands`, but executed only on multilib architectures. +- `extraOutputsToInstall` + Additional derivation outputs to be linked for both target and multi-architecture packages. +- `extraInstallCommands` + Additional commands to be executed for finalizing the derivation with runner script. +- `runScript` + A command that would be executed inside the sandbox and passed all the command line arguments. It defaults to `bash`. +- `profile` + Optional script for `/etc/profile` within the sandbox. + +One can create a simple environment using a `shell.nix` like that: + +```nix +{ pkgs ? import <nixpkgs> {} }: + +(pkgs.buildFHSUserEnv { + name = "simple-x11-env"; + targetPkgs = pkgs: (with pkgs; + [ udev + alsa-lib + ]) ++ (with pkgs.xorg; + [ libX11 + libXcursor + libXrandr + ]); + multiPkgs = pkgs: (with pkgs; + [ udev + alsa-lib + ]); + runScript = "bash"; +}).env +``` + +Running `nix-shell` would then drop you into a shell with these libraries and binaries available. You can use this to run closed-source applications which expect FHS structure without hassles: simply change `runScript` to the application path, e.g. `./bin/start.sh` -- relative paths are supported. + +Additionally, the FHS builder links all relocated gsettings-schemas (the glib setup-hook moves them to `share/gsettings-schemas/${name}/glib-2.0/schemas`) to their standard FHS location. This means you don't need to wrap binaries with `wrapGAppsHook`. |