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35 lines
1.1 KiB
Nix
35 lines
1.1 KiB
Nix
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{
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lib,
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runCommand,
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jq,
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}:
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{
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maxLayers,
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fromImage ? null,
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}:
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runCommand "popularity-contest-layering-pipeline.json" { inherit maxLayers; } ''
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# Compute the number of layers that are already used by a potential
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# 'fromImage' as well as the customization layer. Ensure that there is
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# still at least one layer available to store the image contents.
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# one layer will be taken up by the customisation layer
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usedLayers=1
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${lib.optionalString (fromImage != null) ''
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# subtract number of base image layers
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baseImageLayersCount=$(tar -xOf "${fromImage}" manifest.json | ${lib.getExe jq} '.[0].Layers | length')
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(( usedLayers += baseImageLayersCount ))
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''}
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if ! (( $usedLayers < $maxLayers )); then
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echo >&2 "Error: usedLayers $usedLayers layers to store 'fromImage' and" \
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"'extraCommands', but only maxLayers=$maxLayers were" \
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"allowed. At least 1 layer is required to store contents."
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exit 1
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fi
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availableLayers=$(( maxLayers - usedLayers ))
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# Produce pipeline which uses popularity_contest algo.
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echo '[["popularity_contest"],["limit_layers",'$availableLayers']]' > $out
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''
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