ceamac
a301dfb44f
slocker-lite validates an OCI Image Layout tar, imports its layers into containers-storage's layer store in order, and mounts the assembled image using fuse-overlayfs, printing the resulting merged path. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
90 lines
2.7 KiB
Python
90 lines
2.7 KiB
Python
#!/usr/bin/env python3
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"""Writes a minimal one-layer OCI Image Layout tar to the path given as argv[1].
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Used by meson.build to produce a fixture for the `meson test` smoke test.
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"""
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import gzip
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import hashlib
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import io
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import json
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import sys
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import tarfile
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def sha256_hex(data: bytes) -> str:
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return hashlib.sha256(data).hexdigest()
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def add_bytes(tar: tarfile.TarFile, name: str, data: bytes) -> None:
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info = tarfile.TarInfo(name=name)
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info.size = len(data)
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tar.addfile(info, io.BytesIO(data))
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def main() -> None:
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out_path = sys.argv[1]
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# Uncompressed layer content: a tiny tar with a single file.
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layer_tar_buf = io.BytesIO()
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with tarfile.open(fileobj=layer_tar_buf, mode="w") as layer_tar:
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add_bytes(layer_tar, "hello.txt", b"hello from slocker-lite fixture\n")
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layer_tar_bytes = layer_tar_buf.getvalue()
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diff_id = sha256_hex(layer_tar_bytes)
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layer_gz_bytes = gzip.compress(layer_tar_bytes)
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layer_digest = sha256_hex(layer_gz_bytes)
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config = {
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"architecture": "amd64",
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"os": "linux",
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"config": {},
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"rootfs": {"type": "layers", "diff_ids": [f"sha256:{diff_id}"]},
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}
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config_bytes = json.dumps(config).encode()
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config_digest = sha256_hex(config_bytes)
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manifest = {
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"schemaVersion": 2,
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"mediaType": "application/vnd.oci.image.manifest.v1+json",
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"config": {
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"mediaType": "application/vnd.oci.image.config.v1+json",
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"digest": f"sha256:{config_digest}",
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"size": len(config_bytes),
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},
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"layers": [
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{
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"mediaType": "application/vnd.oci.image.layer.v1.tar+gzip",
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"digest": f"sha256:{layer_digest}",
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"size": len(layer_gz_bytes),
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}
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],
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}
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manifest_bytes = json.dumps(manifest).encode()
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manifest_digest = sha256_hex(manifest_bytes)
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index = {
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"schemaVersion": 2,
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"manifests": [
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{
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"mediaType": "application/vnd.oci.image.manifest.v1+json",
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"digest": f"sha256:{manifest_digest}",
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"size": len(manifest_bytes),
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}
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],
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}
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index_bytes = json.dumps(index).encode()
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oci_layout_bytes = json.dumps({"imageLayoutVersion": "1.0.0"}).encode()
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with tarfile.open(out_path, mode="w") as tar:
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add_bytes(tar, "oci-layout", oci_layout_bytes)
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add_bytes(tar, "index.json", index_bytes)
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add_bytes(tar, f"blobs/sha256/{config_digest}", config_bytes)
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add_bytes(tar, f"blobs/sha256/{manifest_digest}", manifest_bytes)
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add_bytes(tar, f"blobs/sha256/{layer_digest}", layer_gz_bytes)
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if __name__ == "__main__":
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main()
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