tjh.dev
nixpkgs mirror (for testing)
github.com/NixOS/nixpkgs
nix
1{
2 jq,
3 lib,
4 python3,
5 runCommand,
6 writeText,
7}:
8
9{
10 closureRoots,
11 excludePaths ? [ ],
12 maxLayers ? 100,
13 fromImage ? null,
14 debug ? false,
15}:
16
17runCommand "layers.json"
18 {
19 __structuredAttrs = true;
20 exportReferencesGraph.graph = closureRoots;
21 inherit fromImage maxLayers;
22 nativeBuildInputs = [
23 jq
24 python3
25 ];
26 excludePathsFile = writeText "excludePaths" (lib.concatMapStrings (x: x + "\n") excludePaths);
27 }
28 ''
29 # Compute the number of layers that are already used by a potential
30 # 'fromImage' as well as the customization layer. Ensure that there is
31 # still at least one layer available to store the image contents.
32 # one layer will be taken up by the customisation layer
33 usedLayers=1
34
35 if [ -n "$fromImage" ]; then
36 # subtract number of base image layers
37 baseImageLayersCount=$(tar -xOf "$fromImage" manifest.json | jq '.[0].Layers | length')
38 (( usedLayers += baseImageLayersCount ))
39 fi
40
41 if ! (( $usedLayers < $maxLayers )); then
42 echo >&2 "Error: usedLayers $usedLayers layers to store 'fromImage' and" \
43 "'extraCommands', but only maxLayers=$maxLayers were" \
44 "allowed. At least 1 layer is required to store contents."
45 exit 1
46 fi
47 availableLayers=$(( maxLayers - usedLayers ))
48
49 jq .graph "$NIX_ATTRS_JSON_FILE" > referencesGraph
50 ${lib.optionalString debug "export DEBUG=1"}
51 python3 ${./auto-layer.py} referencesGraph $excludePathsFile $availableLayers > $out
52 ''