Warning
This program is experimental and its interface is subject to change.

Name

nix flake info - show flake metadata

Synopsis

nix flake info [option...] flake-url

Examples

  • Show what dwarffs resolves to:

    # nix flake metadata dwarffs
Resolved URL:  github:edolstra/dwarffs
Locked URL:    github:edolstra/dwarffs/f691e2c991e75edb22836f1dbe632c40324215c5
Description:   A filesystem that fetches DWARF debug info from the Internet on demand
Path:          /nix/store/769s05vjydmc2lcf6b02az28wsa9ixh1-source
Revision:      f691e2c991e75edb22836f1dbe632c40324215c5
Last modified: 2021-01-21 15:41:26
Inputs:
├───nix: github:NixOS/nix/6254b1f5d298ff73127d7b0f0da48f142bdc753c
│   ├───lowdown-src: github:kristapsdz/lowdown/1705b4a26fbf065d9574dce47a94e8c7c79e052f
│   └───nixpkgs: github:NixOS/nixpkgs/ad0d20345219790533ebe06571f82ed6b034db31
└───nixpkgs follows input 'nix/nixpkgs'

  • Show information about dwarffs in JSON format:

    # nix flake metadata dwarffs --json | jq .
{
  "description": "A filesystem that fetches DWARF debug info from the Internet on demand",
  "lastModified": 1597153508,
  "locked": {
    "lastModified": 1597153508,
    "narHash": "sha256-VHg3MYVgQ12LeRSU2PSoDeKlSPD8PYYEFxxwkVVDRd0=",
    "owner": "edolstra",
    "repo": "dwarffs",
    "rev": "d181d714fd36eb06f4992a1997cd5601e26db8f5",
    "type": "github"
  },
  "locks": { ... },
  "original": {
    "id": "dwarffs",
    "type": "indirect"
  },
  "originalUrl": "flake:dwarffs",
  "path": "/nix/store/hang3792qwdmm2n0d9nsrs5n6bsws6kv-source",
  "resolved": {
    "owner": "edolstra",
    "repo": "dwarffs",
    "type": "github"
  },
  "resolvedUrl": "github:edolstra/dwarffs",
  "revision": "d181d714fd36eb06f4992a1997cd5601e26db8f5",
  "url": "github:edolstra/dwarffs/d181d714fd36eb06f4992a1997cd5601e26db8f5"
}

Description

This command shows information about the flake specified by the flake reference flake-url. It resolves the flake reference using the flake registry, fetches it, and prints some meta data. This includes:

  • Resolved URL: If flake-url is a flake identifier, then this is the flake reference that specifies its actual location, looked up in the flake registry.

  • Locked URL: A flake reference that contains a commit or content hash and thus uniquely identifies a specific flake version.

  • Description: A one-line description of the flake, taken from the description field in flake.nix.

  • Path: The store path containing the source code of the flake.

  • Revision: The Git or Mercurial commit hash of the locked flake.

  • Revisions: The number of ancestors of the Git or Mercurial commit of the locked flake. Note that this is not available for github flakes.

  • Last modified: For Git or Mercurial flakes, this is the commit time of the commit of the locked flake; for tarball flakes, it's the most recent timestamp of any file inside the tarball.

  • Inputs: The flake inputs with their corresponding lock file entries.

With --json, the output is a JSON object with the following fields:

  • original and originalUrl: The flake reference specified by the user (flake-url) in attribute set and URL representation.

  • resolved and resolvedUrl: The resolved flake reference (see above) in attribute set and URL representation.

  • locked and lockedUrl: The locked flake reference (see above) in attribute set and URL representation.

  • description: See Description above.

  • path: See Path above.

  • revision: See Revision above.

  • revCount: See Revisions above.

  • lastModified: See Last modified above.

  • locks: The contents of flake.lock.

Options

  • --json

    Produce output in JSON format, suitable for consumption by another program.

Common evaluation options

  • --arg name expr

    Pass the value expr as the argument name to Nix functions.

  • --arg-from-file name path

    Pass the contents of file path as the argument name to Nix functions.

  • --arg-from-stdin name

    Pass the contents of stdin as the argument name to Nix functions.

  • --argstr name string

    Pass the string string as the argument name to Nix functions.

  • --debugger

    Start an interactive environment if evaluation fails.

  • --eval-store store-url

    The URL of the Nix store to use for evaluation, i.e. to store derivations (.drv files) and inputs referenced by them.

  • --impure

    Allow access to mutable paths and repositories.

  • --include / -I path

    Add path to search path entries used to resolve lookup paths

    This option may be given multiple times.

    Paths added through -I take precedence over the nix-path configuration setting and the NIX_PATH environment variable.

  • --override-flake original-ref resolved-ref

    Override the flake registries, redirecting original-ref to resolved-ref.

  • --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.

  • --repair

    During evaluation, rewrite missing or corrupted files in the Nix store. During building, rebuild missing or corrupted store paths.

  • --version

    Show version information.

Note

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