import argparse from functools import partial import json from multiprocessing import Pool import os from pathlib import Path import subprocess def dropPrefix(path, nixPrefix): return path[len(nixPrefix + "/") :] def processItem( item, nixPrefix, outDir, compression, compressionCommand, compressionExtension ): narInfoHash = dropPrefix(item["path"], nixPrefix).split("-")[0] narFile = outDir / "nar" / f"{narInfoHash}.nar{compressionExtension}" with open(narFile, "wb") as f: subprocess.run( f"nix-store --dump {item['path']} {compressionCommand}", stdout=f, shell=True, check=True, ) fileHash = ( subprocess.run( ["nix-hash", "--base32", "--type", "sha256", "--flat", narFile], capture_output=True, check=True, ) .stdout.decode() .strip() ) fileSize = os.path.getsize(narFile) finalNarFileName = Path("nar") / f"{fileHash}.nar{compressionExtension}" os.rename(narFile, outDir / finalNarFileName) with open(outDir / f"{narInfoHash}.narinfo", "wt") as f: f.write(f"StorePath: {item['path']}\n") f.write(f"URL: {finalNarFileName}\n") f.write(f"Compression: {compression}\n") f.write(f"FileHash: sha256:{fileHash}\n") f.write(f"FileSize: {fileSize}\n") f.write(f"NarHash: {item['narHash']}\n") f.write(f"NarSize: {item['narSize']}\n") f.write( f"References: {' '.join(dropPrefix(ref, nixPrefix) for ref in item['references'])}\n" ) def main(): parser = argparse.ArgumentParser() parser.add_argument("--compression", choices=["none", "xz", "zstd"]) args = parser.parse_args() compressionCommand = { "none": "", "xz": "| xz -c", "zstd": "| zstd", }[args.compression] compressionExtension = { "none": "", "xz": ".xz", "zstd": ".zst", }[args.compression] outDir = Path(os.environ["out"]) nixPrefix = os.environ["NIX_STORE"] numWorkers = int(os.environ.get("NIX_BUILD_CORES", "4")) with open(os.environ["NIX_ATTRS_JSON_FILE"], "r") as f: closures = json.load(f)["closure"] os.makedirs(outDir / "nar", exist_ok=True) with open(outDir / "nix-cache-info", "w") as f: f.write(f"StoreDir: {nixPrefix}\n") with Pool(processes=numWorkers) as pool: worker = partial( processItem, nixPrefix=nixPrefix, outDir=outDir, compression=args.compression, compressionCommand=compressionCommand, compressionExtension=compressionExtension, ) pool.map(worker, closures) if __name__ == "__main__": main()