Add signed runtime distribution pipeline

tools/release/generate-runtime-distribution.py

@@ -0,0 +1,110 @@
+#!/usr/bin/env python3
+"""Validate and sign a GovOPlaN OCI runtime distribution manifest."""
+
+from __future__ import annotations
+
+import argparse
+import base64
+import json
+from pathlib import Path
+import sys
+
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
+
+
+META_ROOT = Path(__file__).resolve().parents[2]
+sys.path.insert(0, str(META_ROOT / "tools" / "deployment"))
+
+from govoplan_deploy.distribution import (  # noqa: E402
+    DistributionError,
+    canonical_json,
+    canonical_signed_payload,
+    validate_manifest,
+)
+
+
+def build_parser() -> argparse.ArgumentParser:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--descriptor", type=Path, required=True)
+    parser.add_argument("--output", type=Path, required=True)
+    parser.add_argument(
+        "--signing-key",
+        action="append",
+        default=[],
+        metavar="KEY_ID=PRIVATE_PEM",
+        required=True,
+    )
+    return parser
+
+
+def sign_manifest(
+    descriptor: dict[str, object],
+    signing_keys: tuple[tuple[str, Path], ...],
+) -> dict[str, object]:
+    payload = dict(descriptor)
+    payload["signatures"] = [
+        _signature(payload, key_id=key_id, path=path)
+        for key_id, path in signing_keys
+    ]
+    validate_manifest(payload)
+    return payload
+
+
+def _signature(
+    payload: dict[str, object],
+    *,
+    key_id: str,
+    path: Path,
+) -> dict[str, str]:
+    try:
+        key = serialization.load_pem_private_key(path.read_bytes(), password=None)
+    except (OSError, ValueError, TypeError) as exc:
+        raise DistributionError(f"cannot load signing key {key_id!r}") from exc
+    if not isinstance(key, Ed25519PrivateKey):
+        raise DistributionError(f"signing key {key_id!r} is not Ed25519")
+    return {
+        "key_id": key_id,
+        "algorithm": "ed25519",
+        "value": base64.b64encode(key.sign(canonical_signed_payload(payload))).decode(
+            "ascii"
+        ),
+    }
+
+
+def _parse_signing_key(value: str) -> tuple[str, Path]:
+    if "=" not in value:
+        raise DistributionError("--signing-key must use KEY_ID=PRIVATE_PEM")
+    key_id, raw_path = value.split("=", 1)
+    if not key_id or not raw_path:
+        raise DistributionError("--signing-key must use KEY_ID=PRIVATE_PEM")
+    return key_id, Path(raw_path).expanduser().resolve()
+
+
+def main() -> int:
+    args = build_parser().parse_args()
+    try:
+        descriptor = json.loads(args.descriptor.read_text(encoding="utf-8"))
+        if not isinstance(descriptor, dict):
+            raise DistributionError("descriptor root must be an object")
+        if "signatures" in descriptor:
+            raise DistributionError("descriptor must not contain signatures")
+        payload = sign_manifest(
+            descriptor,
+            tuple(_parse_signing_key(value) for value in args.signing_key),
+        )
+        encoded = canonical_json(payload)
+        args.output.parent.mkdir(parents=True, exist_ok=True)
+        temporary = args.output.with_suffix(args.output.suffix + ".tmp")
+        temporary.write_bytes(encoded)
+        temporary.chmod(0o644)
+        temporary.replace(args.output)
+    except (DistributionError, OSError, ValueError, json.JSONDecodeError) as exc:
+        print(f"error: {exc}", file=sys.stderr)
+        return 1
+    print(f"Runtime distribution manifest written to {args.output}")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())