mirror of
https://github.com/NixOS/nix.dev.git
synced 2024-10-18 14:32:43 -04:00
update flake trade-offs, add more links for reference
This commit is contained in:
Valentin Gagarin
parent
90670dd241
commit
f1aded3a30
|
|
@ -11,7 +11,7 @@ The Nix logo is inspired by [an idea for the Haskell logo](https://wiki.haskell.
|
|||
|
||||
## What are flakes?
|
||||
|
||||
See [](flakes).
|
||||
See [](flakes-definition).
|
||||
|
||||
(channel-branches)=
|
||||
## Which channel branch should I use?
|
||||
|
|
|
|||
|
|
@ -1,4 +1,4 @@
|
|||
(flakes)=
|
||||
(flakes-definition)=
|
||||
# Flakes
|
||||
|
||||
What is usually referred to as "flakes" is:
|
||||
|
|
@ -7,14 +7,18 @@ What is usually referred to as "flakes" is:
|
|||
|
||||
[experimental feature]: https://nix.dev/manual/nix/2.18/contributing/experimental-features.html
|
||||
|
||||
## What are flakes?
|
||||
|
||||
Technically, a [flake](https://nix.dev/manual/nix/2.18/command-ref/new-cli/nix3-flake.html#description) is a file system tree that contains a file named `flake.nix` in its root directory.
|
||||
|
||||
Flakes add the following behavior to Nix:
|
||||
|
||||
1. A `flake.nix` file offers a uniform [schema](https://nix.dev/manual/nix/2.18/command-ref/new-cli/nix3-flake.html#flake-format), where:
|
||||
- Other flakes can be referenced as dependencies providing {term}`Nix language` code or other files.
|
||||
1. A `flake.nix` file enforces a [schema], where:
|
||||
- Other flakes are referenced as dependencies providing {term}`Nix language` code or other files.
|
||||
- The values produced by the {term}`Nix expression`s in `flake.nix` are structured according to pre-defined use cases.
|
||||
|
||||
[schema]: https://nix.dev/manual/nix/2.18/command-ref/new-cli/nix3-flake.html#flake-format
|
||||
|
||||
1. References to other flakes can be specified using a dedicated [URL-like syntax](https://nix.dev/manual/nix/2.18/command-ref/new-cli/nix3-flake.html#flake-references).
|
||||
A [flake registry] allows using symbolic identifiers for further brevity.
|
||||
References can be automatically locked to their current specific version and later updated programmatically.
|
||||
|
|
@ -25,7 +29,7 @@ Flakes add the following behavior to Nix:
|
|||
|
||||
[new command line interface]: https://nix.dev/manual/nix/2.18/command-ref/new-cli/nix.html
|
||||
|
||||
Nix handles flakes differently than regular {term}`Nix file`s in the following ways:
|
||||
Nix handles flakes differently than regular {term}`Nix files <Nix file>` in the following ways:
|
||||
|
||||
- The `flake.nix` file is checked for schema validity.
|
||||
|
||||
|
|
@ -40,53 +44,74 @@ Nix handles flakes differently than regular {term}`Nix file`s in the following w
|
|||
|
||||
It means full reproducibility of a Nix expression, and, by extension, the resulting build instructions by default, but also prohibits parameterisation of results by consumers.
|
||||
|
||||
(flakes-controversy)=
|
||||
## Why are flakes controversial?
|
||||
|
||||
{ref}`Flakes <flakes>` were originally proposed in [RFC 49](https://github.com/NixOS/rfcs/pull/49), and have been in development since 2019.
|
||||
[Flakes](flakes-definition) were inspired by [Shea Levy's NixCon 2018 talk](https://www.youtube.com/watch?v=DHOLjsyXPtM), formally proposed in [RFC 49](https://github.com/NixOS/rfcs/pull/49), and have been in development since 2019.
|
||||
Nix introduced the implementation as its first [experimental feature] in 2021.
|
||||
|
||||
[experimental feature]: https://nix.dev/manual/nix/2.18/contributing/experimental-features.html
|
||||
|
||||
The subject is considered controversial among Nix users and developers in terms of design, development processes, and community governance.
|
||||
The subject is considered controversial among Nix users and developers in terms of design, implementation quality, and decision making process.
|
||||
In particular:
|
||||
- The RFC was closed without conclusion, and some design and implementation issues are not yet resolved.
|
||||
Examples include the notion of a global [flake registry], the [impossibility of parameterising flakes](https://github.com/NixOS/nix/issues/2861), and the [new command line interface and flakes being closely tied to each other](https://discourse.nixos.org/t/2023-03-06-nix-team-meeting-minutes-38/26056#cli-stabilisation-announcement-draft-4).
|
||||
- The original implementation introduced [regressions](https://discourse.nixos.org/t/nix-2-4-and-what-s-next/16257) in the [Nix 2.4 release](https://nix.dev/manual/nix/2.18/release-notes/rl-2.4.html), breaking some stable functionality without a [major version](https://semver.org/) increment.
|
||||
- New Nix users were and still are encouraged by various individuals to adopt flakes despite there being no concrete plan or timeline for stabilisation.
|
||||
|
||||
[flake registry]: https://nix.dev/manual/nix/2.18/command-ref/new-cli/nix3-registry.html
|
||||
- The RFC was closed without conclusion, and some fundamental issues are not yet resolved.
|
||||
For example:
|
||||
- The notion of a [global flake registry](https://github.com/NixOS/flake-registry) saw [substantial criticism](https://github.com/NixOS/rfcs/pull/49#issuecomment-635635333) that was never addressed.
|
||||
Additionally, local registry names in Nix expressions [introduce mutable system state](https://github.com/NixOS/nix/issues/7422) and are thus no improvement over [channels](https://nix.dev/manual/nix/2.18/command-ref/nix-channel) in that regard.
|
||||
- It is [impossible to parameterise flakes](https://github.com/NixOS/nix/issues/2861).
|
||||
This means that [flakes downgrade ease of use of the `system` parameter](https://github.com/NixOS/nix/issues/3843) of derivations, for producers and consumers.
|
||||
- the flakes proposal was criticised for [trying to solve too many problems at once](https://github.com/nixos/rfcs/pull/49#issuecomment-521998933) and [at the wrong abstraction layer](https://discourse.nixos.org/t/nixpkgs-cli-working-group-member-search/30517).
|
||||
Part of this is that [the new command line interface and flakes are closely tied to each other](https://discourse.nixos.org/t/2023-03-06-nix-team-meeting-minutes-38/26056#cli-stabilisation-announcement-draft-4).
|
||||
- As [predicted by RFC reviewers](https://github.com/NixOS/rfcs/pull/49#issuecomment-588990425), the original implementation introduced [regressions](https://discourse.nixos.org/t/nix-2-4-and-what-s-next/16257) in the [Nix 2.4 release](https://nix.dev/manual/nix/2.18/release-notes/rl-2.4.html), breaking some stable functionality without a [major version](https://semver.org/) increment.
|
||||
- Copying sources to the Nix store prior to evaluation adds a [significant performance penalty](https://github.com/NixOS/nix/issues/3121), especially for large repositories such as {term}`Nixpkgs`.
|
||||
Work to address this has been [in progress since May 2022](https://github.com/NixOS/nix/pull/6530), but risks introducing [its own set of issues](https://github.com/NixOS/nix/pull/6530#issuecomment-1850565931).
|
||||
- New Nix users were and still are encouraged by various individuals to adopt flakes despite there being no stability guarantees and no timeline to conclude the experiment.
|
||||
|
||||
This led to a situation where the stable interface was only sparsely maintained for multiple years, and repeatedly suffered breakages due to ongoing development.
|
||||
Meanwhile, the new interface was adopted widely enough for evolving its design without negatively affecting users to become very challenging.
|
||||
|
||||
As of the [2022 community survey](https://discourse.nixos.org/t/2022-nix-survey-results/18983), more than half of the user base, a third of which were relative beginners, relied on experimental features.
|
||||
As of the [2022](https://discourse.nixos.org/t/2022-nix-survey-results/18983) and [2023](https://discourse.nixos.org/t/nix-community-survey-2023-results/33124) surveys, more than half of the respondents, a third of which are relative beginners, rely on experimental features.
|
||||
{term}`Nixpkgs` as a contrasting example, while featuring a `flake.nix` for compatibility, does not depend on Nix experimental features in its code base.
|
||||
|
||||
## Should I enable flakes?
|
||||
## Should I use flakes in my project?
|
||||
|
||||
You have to judge for yourself based on your needs.
|
||||
|
||||
[Flakes](https://nix.dev/concepts/flakes) and the `nix` command suite bring multiple improvements that are relevant for both software users and package authors:
|
||||
[Flakes](flakes-definition) emphasize reproducible artifacts and convenience for their consumers, while classic Nix tools center around composable building blocks and customisation options for developers.
|
||||
Both paradigms have their own set of unique concepts and support tooling that have to be learned, with varying ease of use, implementation quality, and support status.
|
||||
At the moment, neither the stable nor the experimental interface is clearly superior to the other in all aspects.
|
||||
|
||||
- The new command-line interface, together with flakes, makes dealing with existing packages significantly more convenient.
|
||||
- The constraints imposed on flakes strengthen reproducibility by default, and enable various performance improvements when interacting with a large Nix package repository like {term}`Nixpkgs`.
|
||||
Flakes and the `nix` command suite bring multiple improvements that are relevant for both software users and package authors:
|
||||
|
||||
- The new command-line interface, together with flakes, makes dealing with existing packages significantly more convenient in many cases.
|
||||
- The constraints imposed on flakes strengthen reproducibility by default, and enable some performance improvements when interacting with a large Nix package repository like {term}`Nixpkgs`.
|
||||
- Flake references allow for easier handling of version upgrades for existing packages or project dependencies.
|
||||
- The [flake schema](https://nixos.wiki/wiki/Flakes#Flake_schema) helps with composing Nix projects from multiple sources in an orderly fashion.
|
||||
- The [flake schema][schema] helps with composing Nix projects from multiple sources in an orderly fashion.
|
||||
|
||||
At the same time, flakes have [fundamental architectural issues](flakes-controversy) and a number of [problems with the implementation](https://github.com/NixOS/nix/issues?q=is%3Aissue+is%3Aopen+label%3Aflakes+sort%3Areactions-%2B1-desc), and there is no coordinated effort to resolve them systematically.
|
||||
There are also still many [open design questions around the `nix` command line interface](https://github.com/NixOS/nix/issues?q=is%3Aissue+is%3Aopen+label%3Anew-cli+sort%3Areactions-%2B1-desc), some of which are currently being worked on.
|
||||
|
||||
While flakes reduce complexity in some regards, they also introduce some with additional mechanisms.
|
||||
You will have to learn more about the system to fully understand how it works.
|
||||
|
||||
Other than that, and below the surface of the flake schema, Nix and the Nix language work exactly the same in both cases.
|
||||
In principle, the same level of reproducibility can be achieved with or without flakes.
|
||||
In particular, the process of adding software to {term}`Nixpkgs` or maintaining {term}`NixOS` modules and configurations is not affected by flakes at all.
|
||||
There is also no evidence that flakes could help solving the scalability challenges of either.
|
||||
|
||||
Both paradigms have their own set of unique concepts and support tooling that have to be learned, with varying ease of use, implementation quality, and support status.
|
||||
At the moment, neither the stable nor the experimental interface is clearly superior to the other in all aspects.
|
||||
While flakes reduce complexity in some regards, they also introduce additional mechanisms and you will have to learn more about the system to fully understand how it works.
|
||||
Finally, there are downsides to relying on [experimental features][experimental feature] in general:
|
||||
|
||||
There are downsides to relying on [experimental features](https://nix.dev/manual/nix/2.18/command-ref/conf-file.html#conf-experimental-features) in general:
|
||||
|
||||
- Interfaces and behaviour of experimental features could still be changed by Nix developers.
|
||||
- Interfaces and behavior of experimental features could still be changed by Nix developers.
|
||||
This may require you to adapt your code at some point in the future, which will be more effort when it has grown in complexity.
|
||||
Currently there is no agreed-upon plan or timeline for stabilising flakes.
|
||||
[Currently there is no concrete timeline for stabilising flakes.](https://discourse.nixos.org/t/stabilising-the-new-nix-command-line-interface/35531#how-does-this-relate-to-flakes-3)
|
||||
In contrast, stable features in Nix can be considered stable indefinitely.
|
||||
- The [Nix maintainer team](https://nixos.org/community/teams/nix.html) focuses on fixing bugs and regressions in stable interfaces, supporting well-understood use cases, as well as improving the internal design and overall contributor experience in order to ease future development.
|
||||
Improvements to experimental features have a low priority.
|
||||
Improvements to experimental features have low priority.
|
||||
- The [Nix documentation team](https://nixos.org/community/teams/documentation.html) focuses on improving documentation and learning materials for stable features and common principles.
|
||||
When using flakes, you will have to rely more heavily on user-to-user support, third-party documentation, and the source code.
|
||||
|
||||
## Further reading
|
||||
|
||||
- [Flakes aren't real and cannot hurt you: a guide to using Nix flakes the non-flake way](https://jade.fyi/blog/flakes-arent-real/) (Jade Lovelace, January 2024)
|
||||
- [Nix Flakes is an experiment that did too much at once...](https://samuel.dionne-riel.com/blog/2023/09/06/flakes-is-an-experiment-that-did-too-much-at-once.html) ([comments](https://discourse.nixos.org/t/nix-flakes-is-an-experiment-that-did-too-much-at-once/32707)) (Samuel Dionne-Riel, September 2023)
|
||||
- [Experimental does not mean unstable](https://determinate.systems/posts/experimental-does-not-mean-unstable) ([comments](https://discourse.nixos.org/t/experimental-does-not-mean-unstable-detsyss-perspective-on-nix-flakes/32703)) (Graham Christensen, September 2023)
|
||||
- [The Nix Hour: comparing flakes to traditional Nix](https://www.youtube.com/watch?v=atmoYyBAhF4) (Silvan Mosberger, November 2022)
|
||||
|
||||
|
|
|
|||
|
|
@ -36,13 +36,15 @@
|
|||
|
||||
A tutorial for getting started with Home Manager.
|
||||
|
||||
- [Manage your dot files with Home Manager](https://ghedam.at/24353/tutorial-getting-started-with-home-manager-for-nix) (Mattia Gheda, 2021)
|
||||
|
||||
- [Nix Shorts](https://github.com/justinwoo/nix-shorts)
|
||||
|
||||
A series of posts on basics of how packaging with Nix works.
|
||||
|
||||
- [NixOS and Flakes - An unofficial book for beginners](https://nixos-and-flakes.thiscute.world) (2023)
|
||||
|
||||
This tutorial is an introduction to {term}`NixOS` using the experimental Nix [Flakes](flakes) functionality.
|
||||
This tutorial is an introduction to {term}`NixOS` using the experimental Nix [Flakes](flakes-definition) functionality.
|
||||
|
||||
## Other videos
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue