nix3-flake-metadata

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

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:
âââânix: github:NixOS/nix/6254b1f5d298ff73127d7b0f0da48f142bdc753c
â ââââlowdown-src: github:kristapsdz/lowdown/1705b4a26fbf065d9574dce47a94e8c7c79e052f
â âââânixpkgs: github:NixOS/nixpkgs/ad0d20345219790533ebe06571f82ed6b034db31
âââânixpkgs 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).