Provenance

1. Property Build
2. Property Copied
3. Property Derivation
4. Property Flake
5. Property Subpath
6. Property Tree
- 6.1. Property type
- 6.2. Property attrs
  - 6.2.1. Property additionalProperties
7. Property Fetchurl
- 7.1. Property type
- 7.2. Property url
8. Property Unknown
- 8.1. Property type
  - 8.1.1. Must not be

Title: Provenance


Type	`combining`
Required	No
Additional properties	Any type allowed

Description: > Warning

This JSON format is currently experimental and subject to change.

Provenance describes where a store object came from, such as the derivation that built it, the flake output that produced that derivation, or the source tree that it was fetched from. It appears in the provenance field of store object info, as shown by e.g. nix path-info --json.

A provenance record is a JSON object with a type field that determines what other fields are present. Most types have a next field that contains the provenance of the thing from which this one was derived (or null if that isn’t known). Thus, provenance forms a chain, going from the store object itself back to its ultimate origin. For example, a store object substituted from a binary cache might have copied provenance, whose next is build provenance, whose next is derivation provenance, and so on.

Future versions of Nix may add new provenance types, and new fields to existing types. Consumers should therefore accept provenance records with a type that they don’t recognise, and ignore fields that they don’t recognise. Nix itself preserves records of unknown types unchanged.

One of(Option)
Build
Copied
Derivation
Flake
Subpath
Tree
Fetchurl
Unknown

1. Property `Build`

Title: Build


Type	`object`
Required	No
Additional properties	Any type allowed
Defined in	#/$defs/build

Description: The store object is an output of a derivation that was built locally or on a remote builder.

Property	Type	Pattern	Title/Description
+ type	enum (of string)	No	-
+ drv	string	No	Derivation
+ output	string	No	Output Name
- buildHost	Combination	No	Build Host
+ system	string	No	System
- tags	object	No	Tags
- next	object	No	Next

1.1. Property `type`


Type	`enum (of string)`
Required	Yes

Must be one of:

“build”

1.2. Property `drv`

Title: Derivation


Type	`string`
Required	Yes
Defined in	JSON format for `StorePath`

Description: The store derivation that was built.

Restrictions
Min length	34
Must match regular expression	`^[0123456789abcdfghijklmnpqrsvwxyz]{32}-.+$` Test

1.3. Property `output`

Title: Output Name


Type	`string`
Required	Yes

Description: The name of the derivation output that corresponds to this store object, e.g. out.

1.4. Property `buildHost`

Title: Build Host


Type	`combining`
Required	No
Additional properties	Any type allowed

Description: The hostname of the machine on which the derivation was built, or null if not known.

One of(Option)
item 0
item 1

1.4.1. Property `item 0`


Type	`string`
Required	No

1.4.2. Property `item 1`


Type	`null`
Required	No

1.5. Property `system`

Title: System


Type	`string`
Required	Yes

Description: The system type of the derivation, e.g. x86_64-linux.

1.6. Property `tags`

Title: Tags


Type	`object`
Required	No
Additional properties	Not allowed

Description: User-defined key/value pairs from the build-provenance-tags setting on the build host, e.g. a CI job URL.

Property	Type	Pattern	Title/Description
- ^[A-Za-z_][A-Za-z0-9_+-]*$	string	Yes	-

1.6.1. Pattern Property `^[A-Za-z_][A-Za-z0-9_+\-]*$`

All properties whose name matches the regular expression ^[A-Za-z_][A-Za-z0-9_+\-]*$ (Test) must respect the following conditions


Type	`string`
Required	No

1.7. Property `next`

Title: Next


Type	`combining`
Required	No
Additional properties	Any type allowed
Defined in	#/$defs/next

Description: The provenance of the derivation, typically of type derivation.

One of(Option)
item 0
Provenance

1.7.1. Property `item 0`


Type	`null`
Required	No

1.7.2. Property `Provenance`

Title: Provenance


Type	`combining`
Required	No
Additional properties	Any type allowed
Same definition as	Provenance

Description: > Warning

This JSON format is currently experimental and subject to change.

2. Property `Copied`

Title: Copied


Type	`object`
Required	No
Additional properties	Any type allowed
Defined in	#/$defs/copied

Description: The store object was copied from another store, typically substituted from a binary cache.

Property	Type	Pattern	Title/Description
+ type	enum (of string)	No	-
+ from	string	No	From
- next	object	No	Next

2.1. Property `type`


Type	`enum (of string)`
Required	Yes

Must be one of:

“copied”

2.2. Property `from`

Title: From


Type	`string`
Required	Yes

Description: The URL of the store from which the store object was copied.

2.3. Property `next`

Title: Next


Type	`combining`
Required	No
Additional properties	Any type allowed
Same definition as	next

Description: The provenance of the store object in the store from which it was copied.

3. Property `Derivation`

Title: Derivation


Type	`object`
Required	No
Additional properties	Any type allowed
Defined in	#/$defs/derivation

Description: The store object is a store derivation that was instantiated by builtins.derivationWithMeta.

Property	Type	Pattern	Title/Description
+ type	enum (of string)	No	-
+ meta	object	No	Metadata
- next	object	No	Next

3.1. Property `type`


Type	`enum (of string)`
Required	Yes

Must be one of:

“derivation”

3.2. Property `meta`

Title: Metadata


Type	`object`
Required	Yes
Additional properties	Any type allowed

Description: The value of the __meta attribute passed to derivationWithMeta, converted to JSON.

3.3. Property `next`

Title: Next


Type	`combining`
Required	No
Additional properties	Any type allowed
Same definition as	next

Description: The provenance of the Nix expression that instantiated the derivation, typically of type flake.

4. Property `Flake`

Title: Flake


Type	`object`
Required	No
Additional properties	Any type allowed
Defined in	#/$defs/flake

Description: The thing was produced by evaluating a flake output.

Property	Type	Pattern	Title/Description
+ type	enum (of string)	No	-
+ flakeOutput	string	No	Flake Output
- pure	boolean	No	Pure
- next	object	No	Next

4.1. Property `type`


Type	`enum (of string)`
Required	Yes

Must be one of:

“flake”

4.2. Property `flakeOutput`

Title: Flake Output


Type	`string`
Required	Yes

Description: The attribute path of the flake output that was evaluated, e.g. packages.x86_64-linux.default.

4.3. Property `pure`

Title: Pure


Type	`boolean`
Required	No

Description: Whether the flake output was evaluated in pure evaluation mode. Defaults to true if absent.

4.4. Property `next`

Title: Next


Type	`combining`
Required	No
Additional properties	Any type allowed
Same definition as	next

Description: The provenance of the flake’s flake.nix file, typically of type subpath.

5. Property `Subpath`

Title: Subpath


Type	`object`
Required	No
Additional properties	Any type allowed
Defined in	#/$defs/subpath

Description: The thing is a file or directory inside another source tree.

Property	Type	Pattern	Title/Description
+ type	enum (of string)	No	-
+ subpath	string	No	Subpath
- next	object	No	Next

5.1. Property `type`


Type	`enum (of string)`
Required	Yes

Must be one of:

“subpath”

5.2. Property `subpath`

Title: Subpath


Type	`string`
Required	Yes

Description: The absolute path of the file or directory within the source tree, e.g. /flake.nix.

5.3. Property `next`

Title: Next


Type	`combining`
Required	No
Additional properties	Any type allowed
Same definition as	next

Description: The provenance of the source tree, typically of type tree.

6. Property `Tree`

Title: Tree


Type	`object`
Required	No
Additional properties	Any type allowed
Defined in	#/$defs/tree

Description: The thing is a source tree fetched by a fetcher, e.g. a flake input.

Property	Type	Pattern	Title/Description
+ type	enum (of string)	No	-
+ attrs	object	No	Attributes

6.1. Property `type`


Type	`enum (of string)`
Required	Yes

Must be one of:

“tree”

6.2. Property `attrs`

Title: Attributes


Type	`object`
Required	Yes
Additional properties	Each additional property must conform to the schema

Description: The attributes of the locked input, as accepted by builtins.fetchTree, except narHash.

Property	Type	Pattern	Title/Description
-	string, integer or boolean	No	-

6.2.1. Property `additionalProperties`


Type	`string, integer or boolean`
Required	No

7. Property `Fetchurl`

Title: Fetchurl


Type	`object`
Required	No
Additional properties	Any type allowed
Defined in	#/$defs/fetchurl

Description: The store object was downloaded from a URL, e.g. by builtins.fetchurl.

Property	Type	Pattern	Title/Description
+ type	enum (of string)	No	-
+ url	string	No	URL

7.1. Property `type`


Type	`enum (of string)`
Required	Yes

Must be one of:

“fetchurl”

7.2. Property `url`

Title: URL


Type	`string`
Required	Yes

Description: The URL from which the store object was downloaded, with any credentials removed.

8. Property `Unknown`

Title: Unknown


Type	`object`
Required	No
Additional properties	Any type allowed
Defined in	#/$defs/unknown

Description: A provenance type not known to this version of Nix.

Property	Type	Pattern	Title/Description
+ type	Combination	No	-

8.1. Property `type`


Type	`combining`
Required	Yes

8.1.1. Must not be


Type	`enum (of string)`
Required	No

Must be one of:

“build”
“copied”
“derivation”
“flake”
“subpath”
“tree”
“fetchurl”

Examples

Build provenance

A store object built from a flake output, showing the full provenance chain back to the flake’s source tree:

{
    "buildHost": "builder-1",
    "drv": "lhj2ix9nrbw9wjab4ywsg9xvc86fm8in-hello-2.12.2.drv",
    "next": {
        "meta": {
            "description": "Program that produces a familiar, friendly greeting",
            "license": {
                "free": true,
                "spdxId": "GPL-3.0-or-later"
            }
        },
        "next": {
            "flakeOutput": "packages.x86_64-linux.default",
            "next": {
                "next": {
                    "attrs": {
                        "lastModified": 1760000000,
                        "owner": "NixOS",
                        "repo": "nixpkgs",
                        "rev": "0b4defa2584313f3b781240b29d61f6f9f7e0df3",
                        "type": "github"
                    },
                    "type": "tree"
                },
                "subpath": "/flake.nix",
                "type": "subpath"
            },
            "pure": true,
            "type": "flake"
        },
        "type": "derivation"
    },
    "output": "out",
    "system": "x86_64-linux",
    "tags": {
        "ci-job": "https://ci.example.org/jobs/1234"
    },
    "type": "build"
}

Copied provenance

A store object substituted from a binary cache:

{
    "from": "https://cache.example.org",
    "next": {
        "buildHost": null,
        "drv": "lhj2ix9nrbw9wjab4ywsg9xvc86fm8in-hello-2.12.2.drv",
        "next": null,
        "output": "out",
        "system": "x86_64-linux",
        "tags": {},
        "type": "build"
    },
    "type": "copied"
}

Source file

A file inside a Git repository:

{
    "next": {
        "attrs": {
            "lastModified": 1760000000,
            "ref": "refs/heads/main",
            "rev": "8f2b1c0d9e4a7b6c5d3e2f1a0b9c8d7e6f5a4b3c",
            "revCount": 42,
            "type": "git",
            "url": "https://example.org/repo.git"
        },
        "type": "tree"
    },
    "subpath": "/builder.sh",
    "type": "subpath"
}

Fetched URL

{
    "type": "fetchurl",
    "url": "https://ftp.gnu.org/gnu/hello/hello-2.12.2.tar.gz"
}

Keyboard shortcuts

Determinate Nix 3.24.0 Reference Manual

Provenance

1. Property Build

1.1. Property type

1.2. Property drv

1.3. Property output

1.4. Property buildHost

1.4.1. Property item 0

1.4.2. Property item 1

1.5. Property system

1.6. Property tags

1.6.1. Pattern Property ^[A-Za-z_][A-Za-z0-9_+\-]*$

1.7. Property next

1.7.1. Property item 0

1.7.2. Property Provenance

2. Property Copied

2.1. Property type

2.2. Property from

2.3. Property next

3. Property Derivation

3.1. Property type

3.2. Property meta

3.3. Property next

4. Property Flake

4.1. Property type

4.2. Property flakeOutput

4.3. Property pure

4.4. Property next

5. Property Subpath

5.1. Property type

5.2. Property subpath

5.3. Property next

6. Property Tree

6.1. Property type

6.2. Property attrs

6.2.1. Property additionalProperties

7. Property Fetchurl

7.1. Property type

7.2. Property url

8. Property Unknown

8.1. Property type

8.1.1. Must not be

Examples

Build provenance

Copied provenance

Source file

Fetched URL

1. Property `Build`

1.1. Property `type`

1.2. Property `drv`

1.3. Property `output`

1.4. Property `buildHost`

1.4.1. Property `item 0`

1.4.2. Property `item 1`

1.5. Property `system`

1.6. Property `tags`

1.6.1. Pattern Property `^[A-Za-z_][A-Za-z0-9_+\-]*$`

1.7. Property `next`

1.7.1. Property `item 0`

1.7.2. Property `Provenance`

2. Property `Copied`

2.1. Property `type`

2.2. Property `from`

2.3. Property `next`

3. Property `Derivation`

3.1. Property `type`

3.2. Property `meta`

3.3. Property `next`

4. Property `Flake`

4.1. Property `type`

4.2. Property `flakeOutput`

4.3. Property `pure`

4.4. Property `next`

5. Property `Subpath`

5.1. Property `type`

5.2. Property `subpath`

5.3. Property `next`

6. Property `Tree`

6.1. Property `type`

6.2. Property `attrs`

6.2.1. Property `additionalProperties`

7. Property `Fetchurl`

7.1. Property `type`

7.2. Property `url`

8. Property `Unknown`

8.1. Property `type`