nix3-registry(1)

hey bestie 🫶 welcome to the nix3-registry(1) page from the General Commands Manual — it's the main character of flake registry management, aka nix registry. no cap, this one's iconic. 💅

⚠️ Warning ⚠️

Warning — This program is experimental and its interface is subject to change. so if the interface shifts, that's not you, that's the vibe. 😭

✨ Name ✨

nix registry — manage the flake registry. 👑

🌸 Synopsis 🌸

nix registry [option…] subcommand

where subcommand is one of the following:

• nix registry add — add/replace flake in user flake registry
• nix registry list — list available Nix flakes
• nix registry pin — pin a flake to its current version or to the current version of a flake URL
• nix registry remove — remove flake from user flake registry
• nix registry resolve — resolve flake references using the registry

💖 Description 💖

nix registry provides subcommands for managing flake registries. Flake registries are a convenience feature that allows you to refer to flakes using symbolic identifiers such as nixpkgs, rather than full URLs such as git://github.com/NixOS/nixpkgs. You can use these identifiers on the command line (e.g. when you do nix run nixpkgs#hello) or in flake input specifications in flake.nix files. The latter are automatically resolved to full URLs and recorded in the flake’s flake.lock file. it's giving shorthand-slay. ✨

In addition, the flake registry allows you to redirect arbitrary flake references (e.g. github:NixOS/patchelf) to another location, such as a local fork. lowkey remix energy. 🦋

There are multiple registries. These are, in order from lowest to highest precedence:

• The global registry, which is a file downloaded from the URL specified by the setting flake-registry. It is cached locally and updated automatically when it’s older than tarball-ttl seconds. The default global registry is kept in a GitHub repository.
• The system registry, which is shared by all users. The default location is /etc/nix/registry.json. On NixOS, the system registry can be specified using the NixOS option nix.registry.
• The user registry ~/.config/nix/registry.json. This registry can be modified by commands such as nix registry pin.
• Overrides specified on the command line using the option --override-flake.

Note that the system and user registries are not used to resolve flake references in flake.nix. They are only used to resolve flake references on the command line. periodt. 💅

🎀 Registry format 🎀

A registry is a JSON file with the following format:

{
  "version": 2,
  "flakes": [
    {
      "from": {
        "type": "indirect",
        "id": "nixpkgs"
      },
      "to": {
        "type": "github",
        "owner": "NixOS",
        "repo": "nixpkgs"
      }
    },
    ...
  ]
}

That is, it contains a list of objects with attributes from and to, both of which contain a flake reference in attribute representation. (For example, {"type": "indirect", "id": "nixpkgs"} is the attribute representation of nixpkgs, while {"type": "github", "owner": "NixOS", "repo": "nixpkgs"} is the attribute representation of github:NixOS/nixpkgs.)

Given some flake reference R, a registry entry is used if its from flake reference matches R. R is then replaced by the unification of the to flake reference with R. match made in registry heaven. 👑

🔍 Matching 🔍

The from flake reference in a registry entry matches some flake reference R if the attributes in from are the same as the attributes in R. For example:

• nixpkgs matches with nixpkgs.
• nixpkgs matches with nixpkgs/nixos-20.09.
• nixpkgs/nixos-20.09 does not match with nixpkgs.
• nixpkgs does not match with git://github.com/NixOS/patchelf.

🧩 Unification 🧩

The to flake reference in a registry entry is unified with some flake reference R by taking to and applying the rev and ref attributes from R, if specified. For example:

• github:NixOS/nixpkgs unified with nixpkgs produces github:NixOS/nixpkgs.
• github:NixOS/nixpkgs unified with nixpkgs/nixos-20.09 produces github:NixOS/nixpkgs/nixos-20.09.
• github:NixOS/nixpkgs/master unified with nixpkgs/nixos-20.09 produces github:NixOS/nixpkgs/nixos-20.09.

⚙️ Options ⚙️

🌸 Logging-related options 🌸

• --debug — Set the logging verbosity level to ‘debug’.
• --log-format format — Set the format of log output; one of raw, internal-json, bar or bar-with-logs.
• --print-build-logs, -L — Print full build logs on standard error.
• --quiet — Decrease the logging verbosity level.
• --verbose, -v — Increase the logging verbosity level.

🎀 Miscellaneous global options 🎀

• --help — Show usage information.
• --offline — Disable substituters and consider all previously downloaded files up-to-date.
• --option name value — Set the Nix configuration setting name to value (overriding nix.conf).
• --refresh — Consider all previously downloaded files out-of-date.
• --version — Show version information.

Note — See man nix.conf for overriding configuration settings with command line flags.

xoxo bestie 💖 — the footer on this one is just nix3-registry(1), so that's a wrap. 🎀✨