Derivation JSON Format
Warning
This JSON format is currently experimental and subject to change.
The JSON serialization of a derivations is a JSON object with the following fields:
-
name
: The name of the derivation. This is used when calculating the store paths of the derivation's outputs. -
version
: Must be3
. This is a guard that allows us to continue evolving this format. The choice of3
is fairly arbitrary, but corresponds to this informal version:-
Version 0: A-Term format
-
Version 1: Original JSON format, with ugly
"r:sha256"
inherited from A-Term format. -
Version 2: Separate
method
andhashAlgo
fields in output specs -
Verison 3: Drop store dir from store paths, just include base name.
Note that while this format is experimental, the maintenance of versions is best-effort, and not promised to identify every change.
-
-
outputs
: Information about the output paths of the derivation. This is a JSON object with one member per output, where the key is the output name and the value is a JSON object with these fields:-
path
: The output path, if it is known in advanced. Otherwise,null
. -
method
: For an output which will be [content addressed], a string representing the method of content addressing that is chosen. Valid method strings are:Otherwise,
null
. -
hashAlgo
: For an output which will be [content addressed], the name of the hash algorithm used. Valid algorithm strings are:blake3
md5
sha1
sha256
sha512
-
hash
: For fixed-output derivations, the expected content hash in base-16.
Example
"outputs": { "out": { "method": "nar", "hashAlgo": "sha256", "hash": "6fc80dcc62179dbc12fc0b5881275898f93444833d21b89dfe5f7fbcbb1d0d62" } }
-
-
inputSrcs
: A list of store paths on which this derivation depends.Example
"inputSrcs": [ "47y241wqdhac3jm5l7nv0x4975mb1975-separate-debug-info.sh", "56d0w71pjj9bdr363ym3wj1zkwyqq97j-fix-pop-var-context-error.patch" ]
-
inputDrvs
: A JSON object specifying the derivations on which this derivation depends, and what outputs of those derivations.Example
"inputDrvs": { "6lkh5yi7nlb7l6dr8fljlli5zfd9hq58-curl-7.73.0.drv": ["dev"], "fn3kgnfzl5dzym26j8g907gq3kbm8bfh-unzip-6.0.drv": ["out"] }
specifies that this derivation depends on the
dev
output ofcurl
, and theout
output ofunzip
. -
system
: The system type on which this derivation is to be built (e.g.x86_64-linux
). -
builder
: The absolute path of the program to be executed to run the build. Typically this is thebash
shell (e.g./nix/store/r3j288vpmczbl500w6zz89gyfa4nr0b1-bash-4.4-p23/bin/bash
). -
args
: The command-line arguments passed to thebuilder
. -
env
: The environment passed to thebuilder
. -
structuredAttrs
: Strucutured Attributes, only defined if the derivation contains them. Structured attributes are JSON, and thus embedded as-is.