Name

       nix flake metadata - show flake metadata

Synopsis

       nix flake metadata [option…] flake-url

Examples

       • Show what nixpkgs resolves to:

       # nix flake metadata nixpkgs
       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 (./nix3-registry.md), 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.

       • --argstr name string
         Pass the string string as the argument name to Nix functions.

       • --eval-store store-url
         The Nix store to use for evaluations.

       • --impure
         Allow access to mutable paths and repositories.

       • --include / -I path
         Add path to the list of locations used to look up <...> file names.

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

       Common flake-related options:

       • --commit-lock-file
         Commit changes to the flake’s lock file.

       • --inputs-from flake-url
         Use the inputs of the specified flake as registry entries.

       • --no-registries
         Don’t allow lookups in the flake registries. This option is  deprecated;  use  --no-use-
         registries.

       • --no-update-lock-file
         Do not allow any updates to the flake’s lock file.

       • --no-write-lock-file
         Do not write the flake’s newly generated lock file.

       • --override-input input-path flake-url
         Override  a  specific  flake input (e.g. dwarffs/nixpkgs). This implies --no-write-lock-
         file.

       • --recreate-lock-file
         Recreate the flake’s lock file from scratch.

       • --update-input input-path
         Update a specific flake input (ignoring its previous entry in the lock file).

                                                                           nix3-flake-metadata(1)