* Clarify stability a bit

* Further stability clarification in CONTRIBUTING.md

* Improve some wording

2023-02-13 14:07:35 -08:00

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The Determinate Nix Installer

nix-installer is an opinionated alternative to the official Nix install scripts.

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
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

Installation Differences

Differing from the current official 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 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:

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

Or, to download a platform specific Installer binary yourself:

$ 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:

$ ./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:

$ ./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:

$ 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

/nix/nix-installer uninstall

As a Github Action

You can use the nix-installer-action Github Action like so:

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 .

In a container

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

When --init none is used, only root or sudoers can run Nix:
sudo -i nix run nixpkgs#hello

For Docker containers (without an init):

# 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
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 an init:

# 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 WSL

If systemd is enabled it's possible to install Nix as normal using the command at the top of this document:

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:

When --init none is used, only root or sudoers can run Nix:
sudo -i nix run nixpkgs#hello

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

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:

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

On Mac:

nix build -L github:determinatesystems/nix-installer#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:

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, which wrap stable std APIs, but are unstable due to it requiring an MSRV bump.

As a library

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:

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 as we utilize Tokio's process groups, which wrap stable std APIs, but are unstable due to it requiring an MSRV bump:

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

Then it's possible to review the documentation:

cargo doc --open -p nix-installer

Documentation is also available via nix build:

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

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