Store Object Info v3

• 1. Property Store Object Info
  • 1.1. Property version
  • 1.2. Property path
  • 1.3. Property narHash
  • 1.4. Property narSize
  • 1.5. Property references
    • 1.5.1. Store Path
  • 1.6. Property ca
    • 1.6.1. Property item 0
    • 1.6.2. Property Content Address
      • 1.6.2.1. Property method
      • 1.6.2.2. Property hash
  • 1.7. Property storeDir
• 2. Property Store Object Info with Impure Fields
  • 2.1. Property version
  • 2.2. Property path
  • 2.3. Property narHash
  • 2.4. Property narSize
  • 2.5. Property references
    • 2.5.1. Store Path
  • 2.6. Property ca
    • 2.6.1. Property item 0
    • 2.6.2. Property Content Address
  • 2.7. Property storeDir
  • 2.8. Property deriver
    • 2.8.1. Property Store Path
    • 2.8.2. Property item 1
  • 2.9. Property registrationTime
  • 2.10. Property ultimate
  • 2.11. Property signatures
    • 2.11.1. Signature
      • 2.11.1.1. Property keyName
      • 2.11.1.2. Property sig
  • 2.12. Property closureSize
  • 2.13. Property provenance
    • 2.13.1. Property item 0
    • 2.13.2. Property Provenance
      • 2.13.2.1. Property Build
        • 2.13.2.1.1. Property type
        • 2.13.2.1.2. Property drv
        • 2.13.2.1.3. Property output
        • 2.13.2.1.4. Property buildHost
          • 2.13.2.1.4.1. Property item 0
          • 2.13.2.1.4.2. Property item 1
        • 2.13.2.1.5. Property system
        • 2.13.2.1.6. Property tags
          • 2.13.2.1.6.1. Pattern Property ^[A-Za-z_][A-Za-z0-9_+\-]*$
        • 2.13.2.1.7. Property next
          • 2.13.2.1.7.1. Property item 0
          • 2.13.2.1.7.2. Property Provenance
      • 2.13.2.2. Property Copied
        • 2.13.2.2.1. Property type
        • 2.13.2.2.2. Property from
        • 2.13.2.2.3. Property next
      • 2.13.2.3. Property Derivation
        • 2.13.2.3.1. Property type
        • 2.13.2.3.2. Property meta
        • 2.13.2.3.3. Property next
      • 2.13.2.4. Property Flake
        • 2.13.2.4.1. Property type
        • 2.13.2.4.2. Property flakeOutput
        • 2.13.2.4.3. Property pure
        • 2.13.2.4.4. Property next
      • 2.13.2.5. Property Subpath
        • 2.13.2.5.1. Property type
        • 2.13.2.5.2. Property subpath
        • 2.13.2.5.3. Property next
      • 2.13.2.6. Property Tree
        • 2.13.2.6.1. Property type
        • 2.13.2.6.2. Property attrs
          • 2.13.2.6.2.1. Property additionalProperties
      • 2.13.2.7. Property Fetchurl
        • 2.13.2.7.1. Property type
        • 2.13.2.7.2. Property url
      • 2.13.2.8. Property Unknown
        • 2.13.2.8.1. Property type
          • 2.13.2.8.1.1. Must not be
• 3. Property Store Object Info with Impure fields and NAR Info
  • 3.1. Property version
  • 3.2. Property path
  • 3.3. Property narHash
  • 3.4. Property narSize
  • 3.5. Property references
  • 3.6. Property ca
  • 3.7. Property storeDir
  • 3.8. Property deriver
    • 3.8.1. Property Store Path
    • 3.8.2. Property item 1
  • 3.9. Property registrationTime
  • 3.10. Property ultimate
  • 3.11. Property signatures
    • 3.11.1. Signature
  • 3.12. Property closureSize
  • 3.13. Property url
  • 3.14. Property compression
  • 3.15. Property downloadHash
  • 3.16. Property downloadSize
  • 3.17. Property closureDownloadSize
  • 3.18. Property provenance
    • 3.18.1. Property item 0
    • 3.18.2. Property Provenance

Title: Store Object Info v3

Description: Information about a store object.

This schema describes the JSON representation of store object metadata as returned by commands like nix path-info --json.

Field Categories

Store object information can come in a few different variations.

Firstly, “impure” fields, which contain non-intrinsic information about the store object, may or may not be included.

Second, binary cache stores have extra non-intrinsic infomation about the store objects they contain.

Thirdly, nix path-info --json --closure-size can compute some extra information about not just the single store object in question, but the store object and its closure.

The impure and NAR fields are grouped into separate variants below. See their descriptions for additional information. The closure fields however as just included as optional fields, to avoid a combinatorial explosion of variants.

1. Property Store Object Info

Title: Store Object Info

Description: Basic store object metadata containing only intrinsic properties. This is the minimal set of fields that describe what a store object contains.

1.1. Property version

Title: Format version (must be 3)

Description: Must be 3. This is a guard that allows us to continue evolving this format. Here is the rough version history:

• Version 0: .narinfo line-oriented format

• Version 1: Original JSON format, with ugly "r:sha256" inherited from .narinfo format.

• Version 2: Use structured JSON type for ca

• Version 3: Use structured JSON type for signatures

Specific value: 3

1.2. Property path

Title: Store Path

Description: Store path to the given store object.

Note: This field may not be present in all contexts, such as when the path is used as the key and the the store object info the value in map.

1.3. Property narHash

Title: NAR Hash

Description: Hash of the file system object part of the store object when serialized as a Nix Archive.

Examples:

"sha256-ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0="

"sha512-IEqPxt2oLwoM7XvrjgikFlfBbvRosiioJ5vjMacDwzWW/RXBOxsH+aodO+pXeJygMa2Fx6cd1wNU7GMSOMo0RQ=="

1.4. Property narSize

Title: NAR Size

Description: Size of the file system object part of the store object when serialized as a Nix Archive.

1.5. Property references

Title: References

Description: An array of store paths, possibly including this one.

1.5.1. Store Path

Title: Store Path

Description: A store path identifying a store object.

This schema describes the JSON representation of store paths as used in various Nix JSON APIs.

Format

Store paths in JSON are represented as strings containing just the hash and name portion, without the store directory prefix.

For example: "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo.drv"

(If the store dir is /nix/store, then this corresponds to the path /nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo.drv.)

Structure

The format follows this pattern: ${digest}-${name}

• hash: Digest rendered in Nix32 (20 hash bytes become 32 ASCII characters)
• name: The package name and optional version/suffix information

1.6. Property ca

Title: Content Address

Description: If the store object is content-addressed, this is the content address of this store object’s file system object, used to compute its store path. Otherwise (i.e. if it is input-addressed), this is null.

1.6.1. Property item 0

Specific value: null

1.6.2. Property Content Address

Title: Content Address

Description: This schema describes the JSON representation of Nix’s ContentAddress type, which conveys information about content-addressing store objects.

Note

For current methods of content addressing, this data type is a bit suspicious, because it is neither simply a content address of a file system object (the method is richer), nor simply a content address of a store object (the hash doesn’t account for the references). It should thus only be used in contexts where the references are also known / otherwise made tamper-resistant.

1.6.2.1. Property method

Title: Content-Addressing Method

Description: A string representing the method of content addressing that is chosen.

Valid method strings are:

• flat (provided the contents are a single file)
• nar
• text
• git

Must be one of:

• “flat”
• “nar”
• “text”
• “git”

1.6.2.2. Property hash

Title: Content Address

Description: This would be the content-address itself.

For all current methods, this is just a content address of the file system object of the store object, as described in the store chapter, and not of the store object as a whole. In particular, the references of the store object are not taken into account with this hash (and currently-supported methods).

Examples:

"sha256-ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0="

"sha512-IEqPxt2oLwoM7XvrjgikFlfBbvRosiioJ5vjMacDwzWW/RXBOxsH+aodO+pXeJygMa2Fx6cd1wNU7GMSOMo0RQ=="

1.7. Property storeDir

Title: Store Directory

Description: The path to the store directory this store object belongs within (e.g. /nix/store).

2. Property Store Object Info with Impure Fields

Title: Store Object Info with Impure Fields

Description: Store object metadata including impure fields that are not intrinsic properties. In other words, the same store object in different stores could have different values for these impure fields.

2.1. Property version

Title: Format version (must be 3)

Description: Must be 3. This is a guard that allows us to continue evolving this format. Here is the rough version history:

• Version 0: .narinfo line-oriented format

• Version 1: Original JSON format, with ugly "r:sha256" inherited from .narinfo format.

• Version 2: Use structured JSON type for ca

• Version 3: Use structured JSON type for signatures

Specific value: 3

2.2. Property path

Title: Store Path

Description: Store path to the given store object.

Note: This field may not be present in all contexts, such as when the path is used as the key and the the store object info the value in map.

2.3. Property narHash

Title: NAR Hash

Description: Hash of the file system object part of the store object when serialized as a Nix Archive.

Examples:

"sha256-ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0="

"sha512-IEqPxt2oLwoM7XvrjgikFlfBbvRosiioJ5vjMacDwzWW/RXBOxsH+aodO+pXeJygMa2Fx6cd1wNU7GMSOMo0RQ=="

2.4. Property narSize

Title: NAR Size

Description: Size of the file system object part of the store object when serialized as a Nix Archive.

2.5. Property references

Title: References

Description: An array of store paths, possibly including this one.

2.5.1. Store Path

Title: Store Path

Description: A store path identifying a store object.

This schema describes the JSON representation of store paths as used in various Nix JSON APIs.

Format

Store paths in JSON are represented as strings containing just the hash and name portion, without the store directory prefix.

For example: "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo.drv"

(If the store dir is /nix/store, then this corresponds to the path /nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo.drv.)

Structure

The format follows this pattern: ${digest}-${name}

• hash: Digest rendered in Nix32 (20 hash bytes become 32 ASCII characters)
• name: The package name and optional version/suffix information

2.6. Property ca

Title: Content Address

Description: If the store object is content-addressed, this is the content address of this store object’s file system object, used to compute its store path. Otherwise (i.e. if it is input-addressed), this is null.

2.6.1. Property item 0

Specific value: null

2.6.2. Property Content Address

Title: Content Address

Description: This schema describes the JSON representation of Nix’s ContentAddress type, which conveys information about content-addressing store objects.

Note

For current methods of content addressing, this data type is a bit suspicious, because it is neither simply a content address of a file system object (the method is richer), nor simply a content address of a store object (the hash doesn’t account for the references). It should thus only be used in contexts where the references are also known / otherwise made tamper-resistant.

2.7. Property storeDir

Title: Store Directory

Description: The path to the store directory this store object belongs within (e.g. /nix/store).

2.8. Property deriver

Title: Deriver

Description: If known, the path to the store derivation from which this store object was produced. Otherwise null.

This is an “impure” field that may not be included in certain contexts.

2.8.1. Property Store Path

Title: Store Path

Description: A store path identifying a store object.

This schema describes the JSON representation of store paths as used in various Nix JSON APIs.

Format

Store paths in JSON are represented as strings containing just the hash and name portion, without the store directory prefix.

For example: "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo.drv"

(If the store dir is /nix/store, then this corresponds to the path /nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo.drv.)

Structure

The format follows this pattern: ${digest}-${name}

• hash: Digest rendered in Nix32 (20 hash bytes become 32 ASCII characters)
• name: The package name and optional version/suffix information

2.8.2. Property item 1

2.9. Property registrationTime

Title: Registration Time

Description: If known, when this derivation was added to the store (Unix timestamp). Otherwise null.

This is an “impure” field that may not be included in certain contexts.

2.10. Property ultimate

Title: Ultimate

Description: Whether this store object is trusted because we built it ourselves, rather than substituted a build product from elsewhere.

This is an “impure” field that may not be included in certain contexts.

2.11. Property signatures

Title: Signatures

Description: Signatures claiming that this store object is what it claims to be. Not relevant for content-addressed store objects, but useful for input-addressed store objects.

This is an “impure” field that may not be included in certain contexts.

2.11.1. Signature

Title: Signature

Description: A cryptographic signature along with the name of the key that produced it.

This schema describes the JSON representation of signatures as used in various Nix JSON APIs.

Version History

• Version 1: Colon-separated string in the format <key-name>:<signature-in-Base64>

• Version 2: Structured object with keyName and sig fields

2.11.1.1. Property keyName

Title: Key Name

Description: The name of the key used to produce this signature

2.11.1.2. Property sig

Title: Signature Data

Description: The raw signature bytes, Base64-encoded

2.12. Property closureSize

Title: Closure Size

Description: The total size of this store object and every other object in its closure.

This field is not stored at all, but computed by traversing the other fields across all the store objects in a closure.

2.13. Property provenance

Title: Provenance

Description: Provenance information about the store object, or null if not available.

2.13.1. Property item 0

2.13.2. Property Provenance

Title: Provenance

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.

2.13.2.1. Property Build

Title: Build

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

2.13.2.1.1. Property type

Must be one of:

• “build”

2.13.2.1.2. Property drv

Title: Derivation

Description: The store derivation that was built.

2.13.2.1.3. Property output

Title: Output Name

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

2.13.2.1.4. Property buildHost

Title: Build Host

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

2.13.2.1.4.1. Property item 0

2.13.2.1.4.2. Property item 1

2.13.2.1.5. Property system

Title: System

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

2.13.2.1.6. Property tags

Title: Tags

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

2.13.2.1.6.1. 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

2.13.2.1.7. Property next

Title: Next

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

2.13.2.1.7.1. Property item 0

2.13.2.1.7.2. Property Provenance

Title: Provenance

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.

2.13.2.2. Property Copied

Title: Copied

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

2.13.2.2.1. Property type

Must be one of:

• “copied”

2.13.2.2.2. Property from

Title: From

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

2.13.2.2.3. Property next

Title: Next

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

2.13.2.3. Property Derivation

Title: Derivation

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

2.13.2.3.1. Property type

Must be one of:

• “derivation”

2.13.2.3.2. Property meta

Title: Metadata

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

2.13.2.3.3. Property next

Title: Next

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

2.13.2.4. Property Flake

Title: Flake

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

2.13.2.4.1. Property type

Must be one of:

• “flake”

2.13.2.4.2. Property flakeOutput

Title: Flake Output

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

2.13.2.4.3. Property pure

Title: Pure

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

2.13.2.4.4. Property next

Title: Next

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

2.13.2.5. Property Subpath

Title: Subpath

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

2.13.2.5.1. Property type

Must be one of:

• “subpath”

2.13.2.5.2. Property subpath

Title: Subpath

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

2.13.2.5.3. Property next

Title: Next

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

2.13.2.6. Property Tree

Title: Tree

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

2.13.2.6.1. Property type

Must be one of:

• “tree”

2.13.2.6.2. Property attrs

Title: Attributes

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

2.13.2.6.2.1. Property additionalProperties

2.13.2.7. Property Fetchurl

Title: Fetchurl

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

2.13.2.7.1. Property type

Must be one of:

• “fetchurl”

2.13.2.7.2. Property url

Title: URL

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

2.13.2.8. Property Unknown

Title: Unknown

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

2.13.2.8.1. Property type

2.13.2.8.1.1. Must not be

Must be one of:

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

3. Property Store Object Info with Impure fields and NAR Info

Title: Store Object Info with Impure fields and NAR Info

Description: The store object info in the “binary cache” family of Nix store type contain extra information pertaining to downloads of the store object in question. (This store info is called “NAR info”, since the downloads take the form of [Nix Archives](../../store/file-system-object/content-address.md#serial-nix-archive, and the metadata is served in a file with a .narinfo extension.)

This download information, being specific to how the store object happens to be stored and transferred, is also considered to be non-intrinsic / impure.

3.1. Property version

Title: Format version (must be 3)

Description: Must be 3. This is a guard that allows us to continue evolving this format. Here is the rough version history:

• Version 0: .narinfo line-oriented format

• Version 1: Original JSON format, with ugly "r:sha256" inherited from .narinfo format.

• Version 2: Use structured JSON type for ca

• Version 3: Use structured JSON type for signatures

3.2. Property path

Title: Store Path

Description: Store path to the given store object.

Note: This field may not be present in all contexts, such as when the path is used as the key and the the store object info the value in map.

3.3. Property narHash

Title: NAR Hash

Description: Hash of the file system object part of the store object when serialized as a Nix Archive.

3.4. Property narSize

Title: NAR Size

Description: Size of the file system object part of the store object when serialized as a Nix Archive.

3.5. Property references

Title: References

Description: An array of store paths, possibly including this one.

3.6. Property ca

Title: Content Address

Description: If the store object is content-addressed, this is the content address of this store object’s file system object, used to compute its store path. Otherwise (i.e. if it is input-addressed), this is null.

3.7. Property storeDir

Title: Store Directory

Description: The path to the store directory this store object belongs within (e.g. /nix/store).

3.8. Property deriver

Title: Deriver

Description: If known, the path to the store derivation from which this store object was produced. Otherwise null.

This is an “impure” field that may not be included in certain contexts.

3.8.1. Property Store Path

Title: Store Path

Description: A store path identifying a store object.

This schema describes the JSON representation of store paths as used in various Nix JSON APIs.

Format

Store paths in JSON are represented as strings containing just the hash and name portion, without the store directory prefix.

For example: "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo.drv"

(If the store dir is /nix/store, then this corresponds to the path /nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo.drv.)

Structure

The format follows this pattern: ${digest}-${name}

• hash: Digest rendered in Nix32 (20 hash bytes become 32 ASCII characters)
• name: The package name and optional version/suffix information

3.8.2. Property item 1

3.9. Property registrationTime

Title: Registration Time

Description: If known, when this derivation was added to the store (Unix timestamp). Otherwise null.

This is an “impure” field that may not be included in certain contexts.

3.10. Property ultimate

Title: Ultimate

Description: Whether this store object is trusted because we built it ourselves, rather than substituted a build product from elsewhere.

This is an “impure” field that may not be included in certain contexts.

3.11. Property signatures

Title: Signatures

Description: Signatures claiming that this store object is what it claims to be. Not relevant for content-addressed store objects, but useful for input-addressed store objects.

This is an “impure” field that may not be included in certain contexts.

3.11.1. Signature

Title: Signature

Description: A cryptographic signature along with the name of the key that produced it.

This schema describes the JSON representation of signatures as used in various Nix JSON APIs.

Version History

• Version 1: Colon-separated string in the format <key-name>:<signature-in-Base64>

• Version 2: Structured object with keyName and sig fields

3.12. Property closureSize

Title: Closure Size

Description: The total size of this store object and every other object in its closure.

This field is not stored at all, but computed by traversing the other fields across all the store objects in a closure.

3.13. Property url

Title: URL

Description: Where to download a compressed archive of the file system objects of this store object.

This is an impure “.narinfo” field that may not be included in certain contexts.

3.14. Property compression

Title: Compression

Description: The compression format that the archive is in.

This is an impure “.narinfo” field that may not be included in certain contexts.

3.15. Property downloadHash

Title: Download Hash

Description: A digest for the compressed archive itself, as opposed to the data contained within.

This is an impure “.narinfo” field that may not be included in certain contexts.

Examples:

"sha256-ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0="

"sha512-IEqPxt2oLwoM7XvrjgikFlfBbvRosiioJ5vjMacDwzWW/RXBOxsH+aodO+pXeJygMa2Fx6cd1wNU7GMSOMo0RQ=="

3.16. Property downloadSize

Title: Download Size

Description: The size of the compressed archive itself.

This is an impure “.narinfo” field that may not be included in certain contexts.

3.17. Property closureDownloadSize

Title: Closure Download Size

Description: The total size of the compressed archive itself for this object, and the compressed archive of every object in this object’s closure.

This is an impure “.narinfo” field that may not be included in certain contexts.

This field is not stored at all, but computed by traversing the other fields across all the store objects in a closure.

3.18. Property provenance

Title: Provenance

Description: Provenance information about the store object, or null if not available.

3.18.1. Property item 0

3.18.2. Property Provenance

Title: Provenance

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.

Examples

Minimal store object (content-addressed)

{
  "ca": {
    "hash": "sha256-EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM=",
    "method": "nar"
  },
  "narHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
  "narSize": 34878,
  "references": [
    "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
    "n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
  ],
  "storeDir": "/nix/store",
  "version": 3
}

Store object with impure fields

{
  "ca": {
    "hash": "sha256-EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM=",
    "method": "nar"
  },
  "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
  "narHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
  "narSize": 34878,
  "references": [
    "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
    "n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
  ],
  "registrationTime": 23423,
  "signatures": [
    {
      "keyName": "asdf",
      "sig": "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=="
    },
    {
      "keyName": "qwer",
      "sig": "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=="
    }
  ],
  "storeDir": "/nix/store",
  "ultimate": true,
  "version": 3
}

Minimal store object (empty)

{
  "ca": null,
  "narHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
  "narSize": 0,
  "references": [],
  "storeDir": "/nix/store",
  "version": 3
}

Store object with all impure fields

{
  "ca": null,
  "deriver": null,
  "narHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
  "narSize": 0,
  "references": [],
  "registrationTime": null,
  "signatures": [],
  "storeDir": "/nix/store",
  "ultimate": false,
  "version": 3
}

NAR info (minimal)

{
  "ca": {
    "hash": "sha256-EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM=",
    "method": "nar"
  },
  "narHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
  "narSize": 34878,
  "references": [
    "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
    "n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
  ],
  "storeDir": "/nix/store",
  "version": 3
}

NAR info (with binary cache fields)

{
  "ca": {
    "hash": "sha256-EMIJ+giQ/gLIWoxmPKjno3zHZrxbGymgzGGyZvZBIdM=",
    "method": "nar"
  },
  "compression": "xz",
  "deriver": "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
  "downloadHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
  "downloadSize": 4029176,
  "narHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
  "narSize": 34878,
  "references": [
    "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar",
    "n5wkd9frr45pa74if5gpz9j7mifg27fh-foo"
  ],
  "registrationTime": 23423,
  "signatures": [
    {
      "keyName": "asdf",
      "sig": "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=="
    },
    {
      "keyName": "qwer",
      "sig": "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=="
    }
  ],
  "storeDir": "/nix/store",
  "ultimate": true,
  "url": "nar/1w1fff338fvdw53sqgamddn1b2xgds473pv6y13gizdbqjv4i5p3.nar.xz",
  "version": 3
}