host Nix reference manual on nix.dev

CONTRIBUTING.md

@@ -22,6 +22,39 @@ Adapted from the [Contributor Covenant] and [The Carpentries Code of Conduct]:
 [Contributor Covenant]: https://github.com/EthicalSource/contributor_covenant/blob/cd7fcf684249786b7f7d47ba49c23a6bcb3233eb/content/version/2/1/code_of_conduct.md
 [The Carpentries Code of Conduct]: https://github.com/carpentries/docs.carpentries.org/blob/4691971d9f49544054410334140a4fd391a738da/topic_folders/policies/code-of-conduct.md
 
+## Updating reference manuals
+
+With the current setup, the Nix manual hosted on nix.dev does not get updated automatically with new releases.
+The following manual steps are required:
+
+- Regularly update the inputs to use the latest versions of the Nix release branches with `nix shell --run "niv update"`
+
+  To avoid long build times, make sure Nix can be fetched from the cache.
+  If it doesn't, find the latest commit that is [built by Hydra](https://hydra.nixos.org/project/nix). For example, to pin Nix 2.18:
+
+  ```bash
+  niv update nix_2-18 -r f5f4de6a550327b4b1a06123c2e450f1b92c73b6
+  ```
+
+- On each new Nix release:
+
+  1. Add the latest version in [`default.nix`](./default.nix).
+     For example, to add Nix 2.19:
+
+     ```bash
+     niv add nixos/nix -n nix_2-19 -b 2.19-maintenance
+     ```
+
+  2. Reference the latest version in [`source/reference/nix-manual.md`](./source/reference/nix-manual.md).
+
+- If an unstable or stable release of Nixpkgs adopt a new version of Nix, update the corresponding references here.
+
+  Also update URLs to the the Nix manual to the version used by Nixpkgs unstable.
+  For example, if one wants to move from 2.18 to 2.19:
+  ```bash
+  sed -i 's#https://nix.dev/manual/nix/2.18/#https://nix.dev/manual/nix/2.19/#g' $(ls **/*.md)
+  ```
+
 ## What you can do
 
 ### You want to learn and use Nix?

default.nix

@@ -25,10 +25,28 @@ let
     buildPhase = ''
       make html
     '';
-    installPhase = ''
-      mkdir -p $out
-      cp -R build/html/* $out/
-    '';
+    installPhase =
+      let
+        # Various versions of the Nix manuals, grep for (nix-manual)=
+        # FIXME: This requires human interaction to update!
+        # See ./CONTRIBUTING.md for details.
+        releases = [
+          "2.19"
+          "2.18"
+          "2.13"
+        ];
+        inputName = version: pkgs.lib.strings.replaceStrings [ "." ] [ "-" ] version;
+        src = version: (import inputs."nix_${inputName version}").default.doc;
+        copy = version: ''
+          cp -R ${src version}/share/doc/nix/manual/* $out/manual/nix/${version}
+        '';
+      in
+      with pkgs.lib.strings;
+      ''
+        mkdir -p $out/manual/nix/{${concatStringsSep "," releases}}
+        ${concatStringsSep "\n" (map copy releases)}
+        cp -R build/html/* $out/
+      '';
   };
 
   devmode =
@@ -68,6 +86,7 @@ in
     inputsFrom = [ nix-dev ];
     packages = [
       devmode
+      pkgs.niv
       pkgs.python310.pkgs.black
       pkgs.vale
     ];

maintainers/documentation-survey.md

@@ -236,13 +236,13 @@ To better navigate the material and judge its relevance, every entry should prov
 
 ### Nix
 
-- https://nixos.org/manual/nix/stable/command-ref/command-ref.html
+- https://nix.dev/manual/nix/2.18/command-ref/command-ref.html
 - https://edolstra.github.io/pubs/phd-thesis.pdf
 
 ### Nix language
 
 - https://edolstra.github.io/pubs/phd-thesis.pdf
-- https://nixos.org/manual/nix/stable/expressions/writing-nix-expressions.html
+- https://nix.dev/manual/nix/2.18/expressions/writing-nix-expressions.html
 - https://github.com/tazjin/nix-1p
 
 ### Nixpkgs

nix/sources.json

@@ -1,4 +1,40 @@
 {
+    "nix_2-13": {
+        "branch": "2.13-maintenance",
+        "description": "Nix, the purely functional package manager",
+        "homepage": "https://nixos.org/",
+        "owner": "nixos",
+        "repo": "nix",
+        "rev": "56eb17906822f14bb348017315cb1ca643da900a",
+        "sha256": "1k0x63l9crkrhdgdclcx8mp6r9mcp4brs67l6hsii1ag8gy2gmj4",
+        "type": "tarball",
+        "url": "https://github.com/nixos/nix/archive/56eb17906822f14bb348017315cb1ca643da900a.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "nix_2-18": {
+        "branch": "2.18-maintenance",
+        "description": "Nix, the purely functional package manager",
+        "homepage": "https://nixos.org/",
+        "owner": "nixos",
+        "repo": "nix",
+        "rev": "f5f4de6a550327b4b1a06123c2e450f1b92c73b6",
+        "sha256": "1g23sxsh9aj7sard5d3ijqfjqbh4fvlvyr73sj3dcdzcqiys5naq",
+        "type": "tarball",
+        "url": "https://github.com/nixos/nix/archive/f5f4de6a550327b4b1a06123c2e450f1b92c73b6.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "nix_2-19": {
+        "branch": "2.19-maintenance",
+        "description": "Nix, the purely functional package manager",
+        "homepage": "https://nixos.org/",
+        "owner": "nixos",
+        "repo": "nix",
+        "rev": "33bacbe220b49ceaaeb817354592a0102fbae087",
+        "sha256": "17fjz3mxqcszxfzpj48f8rqzdqavnnpibpi0ssw7vxmyybrqsqly",
+        "type": "tarball",
+        "url": "https://github.com/nixos/nix/archive/33bacbe220b49ceaaeb817354592a0102fbae087.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
     "nixpkgs": {
         "branch": "nixos-23.05",
         "description": "Nix Packages collection & NixOS",

source/concepts/faq.md

@@ -14,16 +14,16 @@ The Nix logo is inspired by [an idea for the Haskell logo](https://wiki.haskell.
 {ref}`Flakes <flakes>` were originally 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://nixos.org/manual/nix/unstable/contributing/experimental-features.html
+[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.
 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://nixos.org/manual/nix/stable/release-notes/rl-2.4.html), breaking some stable functionality without a [major version](https://semver.org/) increment.
+- 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://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-registry.html
+[flake registry]: https://nix.dev/manual/nix/2.18/command-ref/new-cli/nix3-registry.html
 
 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.
@@ -50,7 +50,7 @@ Both paradigms have their own set of unique concepts and support tooling that ha
 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.
 
-There are downsides to relying on [experimental features](https://nixos.org/manual/nix/stable/command-ref/conf-file.html#conf-experimental-features) 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.
   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.
@@ -60,6 +60,7 @@ There are downsides to relying on [experimental features](https://nixos.org/manu
 - 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.
 
+(channel-branches)=
 ## Which channel branch should I use?
 
 Nixpkgs and NixOS have both stable and rolling releases.
@@ -102,7 +103,7 @@ Yes. There is:
 
 - CPU architecture—great effort being made to avoid compilation of native instructions in favour of hardcoded supported ones.
 - System's current time/date.
-- The filesystem used for building (see also [`TMPDIR`](https://nixos.org/manual/nix/stable/command-ref/env-common.html#env-TMPDIR)).
+- The filesystem used for building (see also [`TMPDIR`](https://nix.dev/manual/nix/2.18/command-ref/env-common.html#env-TMPDIR)).
 - Linux kernel parameters, such as:
   - [IPv6 capabilities](https://github.com/NixOS/nix/issues/5615).
   - binfmt interpreters, e.g., those configured with [`boot.binfmt.emulatedSystems`](https://search.nixos.org/options?show=boot.binfmt.emulatedSystems).

source/concepts/flakes.md

@@ -5,25 +5,25 @@ What is usually referred to as "flakes" is:
 - A policy for managing dependencies between {term}`Nix expressions<Nix expression>`.
 - An [experimental feature] in Nix, implementing that policy and supporting functionality.
 
-[experimental feature]: https://nixos.org/manual/nix/unstable/contributing/experimental-features.html
+[experimental feature]: https://nix.dev/manual/nix/2.18/contributing/experimental-features.html
 
-Technically, a [flake](https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-flake.html#description) is a file system tree that contains a file named `flake.nix` in its root directory.
+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://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-flake.html#flake-format) , where:
+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.
    - The values produced by the {term}`Nix expression`s in `flake.nix` are structured according to pre-defined use cases.
 
-1. References to other flakes can be specified using a dedicated [URL-like syntax](https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-flake.html#flake-references).
+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.
 
-   [flake registry]: https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-registry.html
+   [flake registry]: https://nix.dev/manual/nix/2.18/command-ref/new-cli/nix3-registry.html
 
 1. A [new command line interface], implemented as a separate experimental feature, leverages flakes by accepting flake references in order to build, run, or deploy software defined as a flake.
 
-   [new command line interface]: https://nixos.org/manual/nix/stable/command-ref/new-cli/nix.html
+   [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:
 

source/conf.py

@@ -423,6 +423,11 @@
     # Linkcheck fails on anchors in GH browser/file viewer, see https://github.com/sphinx-doc/sphinx/issues/11484
     r"https://github\.com/.+/.+/blob/.*#.*$",
     r"https://github\.com/.+/.+/tree/.*#.*$",
+    # XXX: we use the web URL to the manuals we host within the build output,
+    # because Sphinx does not have facilities to deploy arbitrary files.
+    # since linkchecking those URLs will fail before actually deploying them,
+    # we ignore them here.
+    r"https://nix.dev/manual/.*$",
 ]
 
 # Anchors are not present in HTML

source/contributing/documentation/index.md

@@ -11,7 +11,7 @@ If you cannot contribute time, consider [donating to the NixOS Foundation's docu
 
 ## Reference manuals
 
-The manuals for [Nix][nix manual] ([source][nix manual src]), [Nixpkgs][Nixpkgs manual] ([source][nixpkgs manual src]), and [NixOS][NixOS manual] ([source][nixos manual src]) are purely reference documentation, specifying interfaces and behavior.
+The manuals for [Nix](nix-manual) ([source][nix manual src]), [Nixpkgs][Nixpkgs manual] ([source][nixpkgs manual src]), and [NixOS][NixOS manual] ([source][nixos manual src]) are purely reference documentation, specifying interfaces and behavior.
 
 They also show example interactions which demonstrate how to use its components, and explain mechanisms where necessary.
 
@@ -31,7 +31,6 @@ You can help by
   - expanding on sections that appear incomplete
   - identifying sections that are not reference documentation and should be moved to nix.dev
 
-[Nix manual]: https://nixos.org/manual/nix
 [nix manual src]: https://github.com/NixOS/nix/tree/master/doc/manual
 [Nixpkgs manual]: https://nixos.org/manual/nixpkgs
 [nixpkgs manual src]: https://github.com/NixOS/nixpkgs/tree/master/doc

source/guides/best-practices.md

@@ -119,15 +119,15 @@ You will often encounter Nix language code samples that refer to `<nixpkgs>`.
 `<...>` is special syntax that was [introduced in 2011] to conveniently access values from the environment variable [`$NIX_PATH`].
 
 [introduced in 2011]: https://github.com/NixOS/nix/commit/1ecc97b6bdb27e56d832ca48cdafd3dbb5185a04
-[`$NIX_PATH`]: https://nixos.org/manual/nix/unstable/command-ref/env-common.html#env-NIX_PATH
+[`$NIX_PATH`]: https://nix.dev/manual/nix/2.18/command-ref/env-common.html#env-NIX_PATH
 
 This means, the value of a lookup path depends on external system state.
 When using lookup paths, the same Nix expression can produce different results.
 
 In most cases, `$NIX_PATH` is set to the latest channel when Nix is installed, and is therefore likely to differ from machine to machine.
 
 :::{note}
-[Channels](https://nixos.org/manual/nix/stable/command-ref/nix-channel.html) are a mechanism for referencing remote Nix expressions and retrieving their latest version.
+[Channels](https://nix.dev/manual/nix/2.18/command-ref/nix-channel.html) are a mechanism for referencing remote Nix expressions and retrieving their latest version.
 :::
 
 The state of a subscribed channel is external to the Nix expressions relying on it.
@@ -184,7 +184,7 @@ We skip it in minimal examples reduce distractions.
 
 ## Updating nested attribute sets
 
-The [attribute set update operator](https://nixos.org/manual/nix/stable/language/operators.html#update) merges two attribute sets.
+The [attribute set update operator](https://nix.dev/manual/nix/2.18/language/operators.html#update) merges two attribute sets.
 
 Example:
 
@@ -250,7 +250,7 @@ If someone builds the project in a directory with a different name, they will ge
 This can be the cause of needless rebuilds.
 
 :::{tip}
-Use [`builtins.path`](https://nixos.org/manual/nix/stable/language/builtins.html#builtins-path) with the `name` attribute set to something fixed.
+Use [`builtins.path`](https://nix.dev/manual/nix/2.18/language/builtins.html#builtins-path) with the `name` attribute set to something fixed.
 
 This will derive the symbolic name of the store path from `name` instead of the working directory:
 

source/guides/troubleshooting.md

@@ -2,7 +2,7 @@
 
 ## What to do if a binary cache is down or unreachable?
 
-Pass [`--option substitute false`](https://nixos.org/manual/nix/stable/command-ref/conf-file#conf-substitute) to Nix commands.
+Pass [`--option substitute false`](https://nix.dev/manual/nix/2.18/command-ref/conf-file#conf-substitute) to Nix commands.
 
 ### How to fix: `error: querying path in database: database disk image is malformed`
 
@@ -13,7 +13,7 @@ Try:
 $ sqlite3 /nix/var/nix/db/db.sqlite "pragma integrity_check"
 ```
 
-Which will print the errors in the [database](https://nixos.org/manual/nix/stable/glossary#gloss-nix-database).
+Which will print the errors in the [database](https://nix.dev/manual/nix/2.18/glossary#gloss-nix-database).
 If the errors are due to missing references, the following may work:
 
 ```shell-session
@@ -25,7 +25,7 @@ $ sqlite3 /nix/var/nix/db/db.sqlite-bkp ".dump" | sqlite3 /nix/var/nix/db/db.sql
 
 This is a [known issue](https://github.com/NixOS/nix/issues/1251).
 
-It means that using a new version of Nix upgraded the SQLite schema of the [database](https://nixos.org/manual/nix/stable/glossary#gloss-nix-database), and then you tried to use an older version Nix.
+It means that using a new version of Nix upgraded the SQLite schema of the [database](https://nix.dev/manual/nix/2.18/glossary#gloss-nix-database), and then you tried to use an older version Nix.
 
 The solution is to dump the database, use the old Nix version to initialize it, and then re-import the data:
 
@@ -39,6 +39,6 @@ $ nix-store --load-db < /tmp/db.dump
 
 ### How to fix: `writing to file: Connection reset by peer`
 
-This may mean you are trying to import a too large file or directory into the [Nix store](https://nixos.org/manual/nix/stable/glossary#gloss-store), or your machine is running out of resources, such as disk space or memory.
+This may mean you are trying to import a too large file or directory into the [Nix store](https://nix.dev/manual/nix/2.18/glossary#gloss-store), or your machine is running out of resources, such as disk space or memory.
 
-Try to reduce the size of the directory to import, or run [garbage collection](https://nixos.org/manual/nix/stable/command-ref/nix-collect-garbage).
+Try to reduce the size of the directory to import, or run [garbage collection](https://nix.dev/manual/nix/2.18/command-ref/nix-collect-garbage).

source/install-nix.md

@@ -81,5 +81,5 @@ $ nix --version
 nix (Nix) 2.11.0
 ```
 
-[multi-user installation]: https://nixos.org/manual/nix/stable/installation/multi-user.html
-[single-user installation]: https://nixos.org/manual/nix/stable/installation/single-user.html
+[multi-user installation]: https://nix.dev/manual/nix/2.18/installation/multi-user.html
+[single-user installation]: https://nix.dev/manual/nix/2.18/installation/single-user.html

source/reference/glossary.md

@@ -7,7 +7,7 @@ Nix
     Read /nɪks/ ("Niks").
 
     :::{seealso}
-    - [Nix Reference Manual](https://nixos.org/manual/nix)
+    - [Nix reference manual](./nix-manual.md)
     - [Nix source code](https://github.com/NixOS/nix)
     :::
 
@@ -16,7 +16,7 @@ Nix language
 
     :::{seealso}
     - [](reading-nix-language)
-    - [Nix language reference](https://nixos.org/manual/nix/stable/language)
+    - [Nix language reference](https://nix.dev/manual/nix/2.18/language)
     :::
 
 Nix expression
@@ -31,7 +31,7 @@ Nixpkgs
     Read /nɪks ˈpækɪʤɪz/ ("Nix packages").
 
     :::{seealso}
-    - [Nixpkgs Reference Manual](https://nixos.org/manual/nixpkgs)
+    - [Nixpkgs reference manual](https://nixos.org/manual/nixpkgs)
     - [Nixpkgs source code](https://github.com/NixOS/nixpkgs)
     :::
 
@@ -41,7 +41,7 @@ NixOS
     Read /nɪks oʊ ɛs/ ("Niks Oh Es").
 
     :::{seealso}
-    - [NixOS Reference Manual](https://nixos.org/manual/nixos)
+    - [NixOS reference manual](https://nixos.org/manual/nixos)
     - [NixOS source code](https://github.com/NixOS/nixpkgs/tree/master/nixos)
     :::
 ```