# Nix Installer

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`nix-installer` is an opinionated, **experimental** Nix installer.


```bash
curl -L https://install.determinate.systems/nix | sh -s -- install
```

## Status

`nix-installer` is **pre-release and experimental**. It is not ready for high reliability use! *Please* don't use it on a business critical machine!

Current and planned support:

* [x] Multi-user Linux (aarch64 and x86_64) with systemd init, no SELinux
* [x] Multi-user MacOS (aarch64 and x86_64)
    + Note: User deletion is currently unimplemented, you need to use a user with a secure token and `dscl . -delete /Users/_nixbuild*` where `*` is each user number.
* [x] Valve Steam Deck
* [ ] Multi-user Linux (aarch64 and x86_64) with systemd init & SELinux
* [ ] Single-user Linux (aarch64 and x86_64)
* [ ] Others...

## Installation Differences

Differing from the current official [Nix](https://github.com/NixOS/nix) installer scripts:

* Nix is installed with the `nix-command` and `flakes` features enabled in the `nix.conf`
* `nix-installer` stores an installation receipt (for uninstalling) at `/nix/receipt.json` as well as a copy of the install binary at `/nix/nix-installer`

## Motivations

The current Nix installer scripts do an excellent job, however they are difficult to maintain. Subtle differences in the shell implementations, and certain characteristics of bash scripts make it difficult to make meaningful changes to the installer.

Our team wishes to experiment with the idea of an installer in a more structured language and see if this is a worthwhile alternative. Along the way, we are also exploring a few other ideas, such as:

* offering users a chance to review an accurate, calculated install plan
* having 'planners' which can create appropriate install plans
* keeping an installation receipt for uninstallation
* offering users with a failing install the chance to do a best-effort revert
* doing whatever tasks we can in parallel

So far, our explorations have been quite fruitful, so we wanted to share and keep exploring.

## Usage

Install Nix with the default planner and options:

```bash
curl -L https://install.determinate.systems/nix | sh -s -- install
```

Or, to download a platform specific Installer binary yourself:

```bash
$ curl -sL -o nix-installer https://install.determinate.systems/nix/nix-installer-x86_64-linux
$ chmod +x nix-installer
```

> `nix-installer` will elevate itself if needed using `sudo`. If you use `doas` or `please` you may need to elevate `nix-installer` yourself.

`nix-installer` installs Nix by following a *plan* made by a *planner*. Review the available planners:

```bash
$ ./nix-installer install --help
Execute an install (possibly using an existing plan)

To pass custom options, select a planner, for example `nix-installer install linux-multi --help`

Usage: nix-installer install [OPTIONS] [PLAN]
       nix-installer install <COMMAND>

Commands:
  linux-multi
          A standard Linux multi-user install
  darwin-multi
          A standard MacOS (Darwin) multi-user install
  steam-deck
          A specialized install suitable for the Valve Steam Deck console
  help
          Print this message or the help of the given subcommand(s)
# ...
```

Planners have their own options and defaults, sharing most of them in common:

```bash
$ ./nix-installer install linux-multi --help
A standard Linux multi-user install

Usage: nix-installer install linux-multi [OPTIONS]

Options:
# ...
      --nix-build-user-count <NIX_BUILD_USER_COUNT>
          Number of build users to create
          
          [env: NIX_INSTALLER_NIX_BUILD_USER_COUNT=]
          [default: 32]

      --nix-build-user-id-base <NIX_BUILD_USER_ID_BASE>
          The Nix build user base UID (ascending)
          
          [env: NIX_INSTALLER_NIX_BUILD_USER_ID_BASE=]
          [default: 3000]
# ...
```

Planners can be configured via environment variable or command arguments:

```bash
$ curl -L https://install.determinate.systems/nix | NIX_BUILD_USER_COUNT=4 sh -s -- install linux-multi --nix-build-user-id-base 4000
# Or...
$ NIX_BUILD_USER_COUNT=4 ./nix-installer install linux-multi --nix-build-user-id-base 4000
```


## Uninstalling

You can remove a `nix-installer`-installed Nix by running

```bash
/nix/nix-installer uninstall
```


## As a Github Action

You can use `nix-installer` as a Github action like so:

```yaml
on:
  pull_request:
  push:
    branches: [main]

jobs:
  lints:
    name: Build
    runs-on: ubuntu-22.04
    steps:
    - uses: actions/checkout@v3
    - name: Install Nix
      uses: DeterminateSystems/nix-installer@main
      with:
        # Allow the installed Nix to make authenticated Github requests.
        # If you skip this, you will likely get rate limited.
        github-token: ${{ secrets.GITHUB_TOKEN }}
    - name: Run `nix build`
      run: nix build .
```


## Building

Since you'll be using `nix-installer` to install Nix on systems without Nix, the default build is a static binary.

Build a portable binary on a system with Nix:

```bash
nix build -L github:determinatesystems/nix-installer#nix-installer-static
```

Then copy the `result/bin/nix-installer` to the machine you wish to run it on.

You can also add `nix-installer` to your system without having Nix:

```bash
RUSTFLAGS="--cfg tokio_unstable" cargo install nix-installer
nix-installer --help
```

To make this build portable, pass ` --target x86_64-unknown-linux-musl`.

> We currently require `--cfg tokio_unstable` as we utilize [Tokio's process groups](https://docs.rs/tokio/1.24.1/tokio/process/struct.Command.html#method.process_group), which wrap stable `std` APIs, but are unstable due to it requiring an MSRV bump.


## As a library

Add `nix-installer` to your dependencies:

```bash
cargo add nix-installer
```

> **Building a CLI?** Check out the `cli` feature flag for `clap` integration.

You'll also need to edit your `.cargo/config.toml` to use `tokio_unstable`:

```toml
# .cargo/config.toml
[build]
rustflags=["--cfg", "tokio_unstable"]
```

Then it's possible to review the [documentation](https://docs.rs/nix-installer/latest/nix_installer/):

```bash
cargo doc --open -p nix-installer
```

Documentation is also available via `nix` build:

```bash
nix build github:DeterminateSystems/nix-installer#nix-installer.doc
firefox result-doc/nix-installer/index.html
```