lix-installer/README.md

# The Determinate Nix Installer

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`nix-installer` is an opinionated alternative to the [official Nix install scripts](https://nixos.org/download.html).


```bash
curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | sh -s -- install
```

The `nix-installer` tool is ready to use in a number of environments:

| Platform                     | Multi User         | `root` only | Maturity          |
|------------------------------|:------------------:|:-----------:|:-----------------:|
| Linux (x86_64 & aarch64)     | ✓ (via [systemd])  | ✓           | Stable            |
| MacOS (x86_64 & aarch64)     | ✓                  |             | Stable (See note) |
| Valve Steam Deck (SteamOS)   | ✓                  |             | Stable            |
| WSL2 (x86_64 & aarch64)      | ✓ (via [systemd])  | ✓           | Stable            |
| Podman Linux Containers      | ✓ (via [systemd])  | ✓           | Stable            |
| Docker Containers            |                    | ✓           | Stable            |
| Linux (i686)                 | ✓ (via [systemd])  | ✓           | Unstable          |

> **Note**
> On **MacOS only**, removing users and/or groups may fail if there are no users who are logged in graphically.

## Installation Differences

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

* In `nix.conf`:
  + the `nix-command` and `flakes` features are enabled
  + `bash-prompt-prefix` is set
  + `auto-optimise-store` is set to `true`
  * `extra-nix-path` is set to `nixpkgs=flake:nixpkgs`
* an installation receipt (for uninstalling) is stored at `/nix/receipt.json` as well as a copy of the install binary at `/nix/nix-installer`
* `nix-channel --update` is not run, `~/.nix-channels` is not provisioned
* `NIX_SSL_CERT_FILE` is set in the various shell profiles if the `ssl-cert-file` argument is used.

## Motivations

The current Nix install 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 --proto '=https' --tlsv1.2 -sSf -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
```

> **Note**
> `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
          A planner for Linux installs
  steam-deck
          A planner suitable for the Valve Steam Deck running SteamOS
  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 --help
A planner for Linux installs

Usage: nix-installer install linux [OPTIONS]

Options:
# ...
      --nix-build-group-name <NIX_BUILD_GROUP_NAME>
          The Nix build group name
          
          [env: NIX_INSTALLER_NIX_BUILD_GROUP_NAME=]
          [default: nixbld]

      --nix-build-group-id <NIX_BUILD_GROUP_ID>
          The Nix build group GID
          
          [env: NIX_INSTALLER_NIX_BUILD_GROUP_ID=]
          [default: 3000]
# ...
```

Planners can be configured via environment variable or command arguments:

```bash
$ curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | NIX_BUILD_GROUP_NAME=nixbuilder sh -s -- install linux-multi --nix-build-group-id 4000
# Or...
$ NIX_BUILD_GROUP_NAME=nixbuilder ./nix-installer install linux-multi --nix-build-group-id 4000
```


## Uninstalling

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

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


## As a Github Action

You can use the [`nix-installer-action`](https://github.com/DeterminateSystems/nix-installer-action) 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-action@main
    - name: Run `nix build`
      run: nix build .
```

## Without systemd (Linux only)

> **Warning**
> When `--init none` is used, _only_ `root` or users who can elevate to `root` privileges can run Nix:
>
> ```bash
> sudo -i nix run nixpkgs#hello
> ```

If you don't use [systemd], you can still install Nix by explicitly specifying the `linux` plan and `--init none`:

```bash
curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | sh -s -- install linux --init none
```

## In a container

In Docker/Podman containers or WSL2 instances where an init (like `systemd`) is not present, pass `--init none`.

> **Warning**
> When `--init none` is used, _only_ `root` or users who can elevate to `root` privileges can run Nix:
>
> ```bash
> sudo -i nix run nixpkgs#hello
> ```

For Docker containers (without an init):

```dockerfile
# Dockerfile
FROM ubuntu:latest
RUN apt update -y
RUN apt install curl -y
COPY nix-installer /nix-installer
RUN /nix-installer install linux --init none --no-confirm
ENV PATH="${PATH}:/nix/var/nix/profiles/default/bin"
RUN nix run nixpkgs#hello
```

Podman containers require `sandbox = false` in your `Nix.conf`.

For podman containers without an init:

```dockerfile
# Dockerfile
FROM ubuntu:latest
RUN apt update -y
RUN apt install curl -y
COPY nix-installer /nix-installer
RUN /nix-installer install linux --extra-conf "sandbox = false" --init none --no-confirm
ENV PATH="${PATH}:/nix/var/nix/profiles/default/bin"
RUN nix run nixpkgs#hello
```

For Podman containers with a systemd init:

```dockerfile
# Dockerfile
FROM ubuntu:latest
RUN apt update -y
RUN apt install curl systemd -y
COPY nix-installer /nix-installer
RUN /nix-installer install linux --extra-conf "sandbox = false" --no-start-daemon --no-confirm
ENV PATH="${PATH}:/nix/var/nix/profiles/default/bin"
RUN nix run nixpkgs#hello
CMD [ "/usr/sbin/init" ]
```

## In WSL2

If [systemd is enabled](https://ubuntu.com/blog/ubuntu-wsl-enable-systemd) it's possible to install Nix as normal using the command at the top of this document:

```bash
curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | sh -s -- install
```

If systemd is not enabled, pass `--init none` at the end of the command:

> **Warning**
> When `--init none` is used, _only_ `root` or users who can elevate to `root` privileges can run Nix:
>
> ```bash
> sudo -i nix run nixpkgs#hello
> ```


```bash
curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | sh -s -- install linux --init none
```

## Skip confirmation

If you'd like to bypass the confirmation step, you can apply the `--no-confirm` flag:

```bash
curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | sh -s -- install --no-confirm
```

This is especially useful when using the installer in non-interactive scripts.

## Building a binary

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

Build a portable Linux binary on a system with Nix:

```bash
# to build a local copy
nix build -L ".#nix-installer-static"
# to build the remote main development branch
nix build -L "github:determinatesystems/nix-installer#nix-installer-static"
# for a specific version of the installer:
export NIX_INSTALLER_TAG="v0.6.0"
nix build -L "github:determinatesystems/nix-installer/$NIX_INSTALLER_TAG#nix-installer-static"
```

On Mac:

```bash
# to build a local copy
nix build -L ".#nix-installer"
# to build the remote main development branch
nix build -L "github:determinatesystems/nix-installer#nix-installer"
# for a specific version of the installer:
export NIX_INSTALLER_TAG="v0.6.0"
nix build -L "github:determinatesystems/nix-installer/$NIX_INSTALLER_TAG#nix-installer"
```

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

You can also add `nix-installer` to a system without Nix via `cargo`:

```bash
# to build and run a local copy
RUSTFLAGS="--cfg tokio_unstable" cargo run -- --help
# to build the remote main development branch
RUSTFLAGS="--cfg tokio_unstable" cargo install --git https://github.com/DeterminateSystems/nix-installer
nix-installer --help
# for a specific version of the installer:
export NIX_INSTALLER_TAG="v0.6.0"
RUSTFLAGS="--cfg tokio_unstable" cargo install --git https://github.com/DeterminateSystems/nix-installer --tag $NIX_INSTALLER_TAG
nix-installer --help
```

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

> **Note**
> 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

> **Warning**
> Use as a library is still experimental, if you're using this, please let us know and we can make a path to stablization.

Add `nix-installer` to your dependencies:

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

If you are **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` 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:

```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
```

## Quirks

While `nix-installer` tries to provide a comprehensive and unquirky experience, there are unfortunately some issues which may require manual intervention or operator choices.

### Using MacOS remote SSH builders, Nix binaries are not on `$PATH`

When connecting to a Mac remote SSH builder users may sometimes see this error:

```bash
$ nix store ping --store "ssh://$USER@$HOST"
Store URL: ssh://$USER@$HOST
zsh:1: command not found: nix-store
error: cannot connect to '$USER@$HOST'
```

The way MacOS populates the `PATH` environment differs from other environments. ([Some background](https://gist.github.com/Linerre/f11ad4a6a934dcf01ee8415c9457e7b2))

There are two possible workarounds for this:

* **(Preferred)** Update the remote builder URL to include the `remote-program` parameter pointing to `nix-store`. For example:
  ```bash
  nix store ping --store "ssh://$USER@$HOST?remote-program=/nix/var/nix/profiles/default/bin/nix-store"
  ```
  If you are unsure where the `nix-store` binary is located, run `which nix-store` on the remote.
* Update `/etc/zshenv` on the remote so that `zsh` populates the Nix path for every shell, even those that are neither *interactive* or *login*:
  ```bash
  # Nix
  if [ -e '/nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh' ]; then
      . '/nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh'
  fi
  # End Nix
  ```
  <details>
    <summary>This strategy has some behavioral caveats, namely, <code>$PATH</code> may have unexpected contents</summary>

    For example, if `$PATH` gets unset then a script invoked, `$PATH` may not be as empty as expected:
    ```bash
    $ cat example.sh     
    #! /bin/zsh
    echo $PATH
    $ PATH= ./example.sh 
    /Users/ephemeraladmin/.nix-profile/bin:/nix/var/nix/profiles/default/bin:
    ```
    This strategy results in Nix's paths being present on `$PATH` twice and may have a minor impact on performance.

  </details>

## Diagnostics

The goal of the Determinate Nix Installer is to successfully and correctly install Nix.
The `curl | sh` pipeline and the installer collects a little bit of diagnostic information to help us make that true.

Here is a table of the [diagnostic data we collect][diagnosticdata]:

| Field                 | Use                                                                                                   |
| --------------------- | ----------------------------------------------------------------------------------------------------- |
| `version`             | The version of the Determinate Nix Installer.                                                         |
| `planner`             | The method of installing Nix (`linux`, `macos`, `steam-deck`)                                         |
| `configured_settings` | The names of planner settings which were changed from their default. Does _not_ include the values.   |
| `os_name`             | The running operating system.                                                                         |
| `os_version`          | The version of the operating system.                                                                  |
| `triple`              | The architecture/operating system/binary format of your system.                                       |
| `is_ci`               | Whether the installer is being used in CI (e.g. GitHub Actions).                                      |
| `action`              | Either `Install` or `Uninstall`.                                                                      |
| `status`              | One of `Success`, `Failure`, `Pending`, or `Cancelled`.                                               |
| `failure_chain`     | A high level description of what the failure was, if any. For example: `Command("diskutil")` if the command `diskutil list` failed. |

To disable diagnostic reporting, set the diagnostics URL to an empty string by passing `--diagnostic-endpoint=""` or setting `NIX_INSTALLER_DIAGNOSTIC_ENDPOINT=""`.

You can read the full privacy policy for [Determinate Systems][detsys], the creators of the Determinate Nix Installer, [here][privacy].

[detsys]: https://determinate.systems/
[diagnosticdata]: https://github.com/DeterminateSystems/nix-installer/blob/f9f927840d532b71f41670382a30cfcbea2d8a35/src/diagnostics.rs#L29-L43
[privacy]: https://determinate.systems/privacy
[systemd]: https://systemd.io