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easily build most Haskell programs into fully static Linux executables
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README.md

static-haskell-nix

With this repository you can easily build most Haskell programs into fully static Linux executables.

  • results are fully static executables (ldd says not a dynamic executable)
  • to make that possible, each exe and all dependencies (including ghc) are built against musl instead of glibc

History

glibc encourages dynamic linking to the extent that correct functionality under static linking is somewhere between difficult and bug-ridden. For this reason, static linking, despite its many advantages (details here) has become less and less common.

Due to GHC's dependency on a libc, and many libraries depending on C libraries for which Linux distributions often do not include static library archive files, this situation has resulted in fully static Haskell programs being extremely hard to produce for the common Haskeller, even though the language is generally well-suited for static linking.

This project solves this.

It was inspired by a blog post by Vaibhav Sagar, and a comment by Will Dietz about musl.

Work on this so far was sponsored largely by my free time, FP Complete and their clients, and the contributors mentioned here.

By now we have a nixpkgs issue on Fully static Haskell executables (progress on which is currently this repo, with plans to later merge it into nixpkgs), and a merged nixpkgs overlay for static nixpkgs in general.

Building a minimal example (don't use this in practice)

default.nix builds an example executable (originally from https://github.com/vaibhavsagar/experiments). Run:

NIX_PATH=nixpkgs=nixpkgs nix-build --no-link

This prints a path that contains the fully linked static executable in the bin subdirectory.

This example is so that you get the general idea. In practice, you probably want to use one of the approaches from the "Building arbitrary packages" or "Building stack projects" sections below.

Binary caches for faster building (optional)

Install cachix and run cachix use static-haskell-nix before your nix-build.

If you get a warning during cachix use, read this.

If you don't want to install cachix for some reason or cachix use doesn't work, you should also be able to manually set up your nix.conf to have contents like this:

substituters = https://cache.nixos.org https://static-haskell-nix.cachix.org
trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= static-haskell-nix.cachix.org-1:Q17HawmAwaM1/BfIxaEDKAxwTOyRVhPG5Ji9K3+FvUU=

Note that you may not get cached results if you use a different nix version than I used to produce the cache (I used 2.0.4 as of writing, which you can get from here).

Building arbitrary packages

The survey directory maintains a select set of Haskell executables that are known and not known to work with this approach; contributions are welcome to grow the set of working executables. Run for example:

NIX_PATH=nixpkgs=nixpkgs nix-build --no-link survey/default.nix -A working

There are multiple package sets available in the survey (select via -A):

  • working -- build all exes known to be working
  • notWorking -- build all exes known to be not working (help welcome to make them work)
  • haskellPackages.somePackage -- build a specific package from our overridden package set

If you are a nix user, you can easily import this functionality and add an override to add your own packages.

Building stack projects

The static-stack2nix-builder-example directory shows how to build any stack-based project statically.

Another example of this is the the official static build of stack itself. See the static-stack directory for how that's done. stack is a big package with many dependencies, demonstrating that this works also for large projects.

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