# Building Isle

Building from source requires [nix][nix].

(*NOTE* The first time you run some of these builds a lot of things will be
built from scratch. If you have not otherwise configured it, nix might be using
a tmpfs as its build directory, and the capacity of this tmpfs will probably be
exceeded by this build. You can change your build directory to somewhere on-disk
by setting the TMPDIR environment variable for `nix-daemon` (see [this github
issue][tmpdir-gh].))

[nix]: https://nixos.wiki/wiki/Nix_package_manager
[tmpdir-gh]: https://github.com/NixOS/nix/issues/2098#issuecomment-383243838

## Current System

You can build an AppImage for your current system by running the following from
the project's root:

```
nix-build -A build.appImage
```

The resulting binary can be found under `result/bin`.

## Cross-Compile

An AppImage can be cross-compiled by passing the `hostSystem` argument:

```
nix-build --argstr hostSystem "x86_64-linux" -A build.appImage
```

Supported system strings are enumerated in `nix/pkgs.nix`.

## Alternative Build Targets

Besides AppImage, Isle supports building alternative package types which are
targetted at different specific operating systems. Each of these has its own
`build.*` target.

* AppImage (all OSs): `nix-build -A build.appImage`
* Arch Linux package: `nix-build -A build.archPkg`

All targets theoretically support passing in a `hostSystem` argument to
cross-compile to a different architecture or OS, but some targets may not make
sense with some `hostSystem` values.