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https://github.com/lf-/flakey-profile
Declarative profiles with nix flakes
https://github.com/lf-/flakey-profile
Last synced: about 6 hours ago
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Declarative profiles with nix flakes
- Host: GitHub
- URL: https://github.com/lf-/flakey-profile
- Owner: lf-
- Created: 2023-11-05T02:47:06.000Z (11 months ago)
- Default Branch: main
- Last Pushed: 2024-04-12T05:09:52.000Z (6 months ago)
- Last Synced: 2024-04-13T15:22:37.759Z (6 months ago)
- Language: Nix
- Size: 19.5 KB
- Stars: 43
- Watchers: 4
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSES/CC0-1.0.txt
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README
# flakey-profile
This is a trivial tool to create declarative profiles with Nix flakes. This is
achieved with the same mechanisms as used by home-manager and NixOS: `nix-env
--set`, `nix-env --list-generations`, and `nix-env --rollback`.
The purpose of this tool is that people stop stubbing their toes on `nix
profile` and `nix-env` for non-declarative uses on non-NixOS systems by
providing a declarative alternative using flakes to pin versions of things.
## Non-goals
- Support `nix profile list` as [complained about
here](https://discourse.nixos.org/t/transitioning-from-imperative-to-declarative-package-management-with-nix-alone/28728#disadvantages-18).
We are in favour of the removal of `nix profile` from the Nix codebase in
lieu of stabilization.
- Compatibility with imperative package management: there is no clear way to
share a profile with an imperative setup.
We might write a migration script in the future that takes `nix profile list
--json` and converts it into a flake.
- Do similar things to home-manager for services or other things. This is just
a replacement for `nix-env` and `nix profile` and nothing more.
## Related work
- [home-mangler](https://github.com/home-mangler/home-mangler), which uses
a few hundred lines of Rust to wrangle `nix profile` into having exactly the
expected packages installed. Their approach makes `nix profile list` work. By
comparison, this project consists of two lines of shell script that bypass
`nix profile` altogether.
- [nixos-rebuild](https://github.com/nixos/nixpkgs/blob/cc625486c48890c37ced7759727c51dd17d20fd3/pkgs/os-specific/linux/nixos-rebuild/nixos-rebuild.sh#L608),
which uses the same methods to achieve its goals.
- [home-manager](https://github.com/nix-community/home-manager/blob/8765d4e38aa0be53cdeee26f7386173e6c65618d/modules/files.nix#L272)
which is implemented via inexplicable cursed crimes for `nix profile` or the
same method as this otherwise.
- [Flakes as a unified format for profiles](https://discourse.nixos.org/t/flakes-as-a-unified-format-for-profiles/29476)
- [Stop Using nix-env](https://stop-using-nix-env.privatevoid.net/)
## Usage
To use it, see the template in `templates/default`, or included below, or run:
```
nix flake init -t github:lf-/flakey-profile#templates.default
```
Flake example:
```nix
# SPDX-FileCopyrightText: 2023 Jade Lovelace
#
# SPDX-License-Identifier: CC0-1.0
{
description = "Basic usage of flakey-profile";
inputs = {
flakey-profile.url = "github:lf-/flakey-profile";
nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
flake-utils.url = "github:numtide/flake-utils";
};
outputs = { self, nixpkgs, flake-utils, flakey-profile }:
flake-utils.lib.eachDefaultSystem (system:
let
pkgs = import nixpkgs {
inherit system;
};
in
{
# Any extra arguments to mkProfile are forwarded directly to pkgs.buildEnv.
#
# Usage:
# Switch to this flake:
# nix run .#profile.switch
# Revert a profile change (note: does not revert pins):
# nix run .#profile.rollback
# Build, without switching:
# nix build .#profile
# Pin nixpkgs in the flake registry and in NIX_PATH, so that
# `nix run nixpkgs#hello` and `nix-shell -p hello --run hello` will
# resolve to the same hello as below [should probably be run as root, see README caveats]:
# sudo nix run .#profile.pin
packages.profile = flakey-profile.lib.mkProfile {
inherit pkgs;
# Specifies things to pin in the flake registry and in NIX_PATH.
pinned = { nixpkgs = toString nixpkgs; };
paths = with pkgs; [
hello
];
};
});
}
```
Then, use the following commands to do things with the new profile:
### Build the profile and switch to it
```
nix run .#profile.switch
```
### Revert a profile change
> **Warning**: This does not rollback the actions of `profile.pin`. To roll
> that back, revert to the previous version of the profile using a version
> control system and run `profile.pin` again.
```
nix run .#profile.rollback
```
### Build, without switching
```
nix build .#profile
```
### Update package versions
```
nix flake lock --update-input nixpkgs
```
or
```
nix flake update
```
then
```
nix run .#profile.switch
```
### Pin nixpkgs in the [flake registry] and in [`NIX_PATH`][nix_path_proc]
This makes `nix run nixpkgs#hello` and `nix-shell -p hello --run hello` give
you the same `hello` as if you listed it in your profile.
> [!IMPORTANT]
> We recommend only running this command as root, since by default the only
> channels used are on root's profile, and are used for `nix upgrade-nix` and
> other uses of nix as root.
> [!WARNING]
> This does not support revert internally; see below for more
> details. To revert pinning, use source control to get the previous version of
> the profile and run the pinning operation again.
```
nix run .#profile.pin
```
#### Context
The [flake registry] is used to resolve unqualified flake names such as
`nixpkgs` in `nix run nixpkgs#hello`, and can be overridden on a per-user or
system-wide basis. `NIX_PATH` is used to resolve `` and other
references in angle brackets, and if not present, [this
procedure][nix_path_proc] is used. By running `profile.pin`, both the flake
registry and the channel of the running user will be overridden to point to the
`nixpkgs` you used to build your profile.
[flake registry]: https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-registry.html#registry-format
[nix_path_proc]: https://nixos.org/manual/nix/stable/command-ref/env-common.html#env-NIX_PATH
> [!NOTE]
> We don't provide an easy way of rolling back a pin, since the Nix
> flake registry is not managed with profiles and the semantics of keeping
> everything in sync when reverting don't really work out. We suggest rolling
> back pins by reverting to the previous version in your preferred version
> control system, then rerunning `pin`.
>
> In a different implementation, we would just use an activation script to
> achieve this the same way as NixOS and home-manager, however, that conflicts
> with the goals of this project.
>
> If it is useful to fixing a system, the things changed are in `~/.config/nix/registry.json`
> (`/etc/nix/registry.json` if run as root), and linked to from
> `~/.nix-defexpr/`. Channels can be rolled back with
> `nix-env --profile $(readlink ~/.nix-defexpr/channels) --rollback`
> or for root, `sudo nix-env --profile $(readlink ~/.nix-defexpr/channels_root) --rollback`.
> The former, not much can be done about, and it's probably easiest to just
> delete the `registry.json` if it's broken.
## Common problems
It seems that often people run into an issue where
`/nix/var/nix/profiles/per-user/$USER` does not exist. If this is the case, you
can simply `sudo mkdir -p /nix/var/nix/profiles/per-user/$USER && sudo chown
$USER /nix/var/nix/profiles/per-user/$USER`. Or, alternatively, `nix-env -f
'' -iA hello` might fix it, but if it does not, try the other one.
This has so far been observed on macOS, however we are unsure if this is a Mac
only bug.