feat(mosaic): add correlated lease promotion CLI

packages/mosaic/framework/tools/lease-broker/promote-complete.py

@@ -10,15 +10,18 @@ import secrets
 import stat
 import subprocess
 import sys
+import time
 from collections.abc import Callable, Mapping
 from pathlib import Path
 from typing import Final, NamedTuple, TextIO
 
 MAX_FRAME: Final = 64 * 1024
 PROMOTER_TIMEOUT_SECONDS: Final = 10.0
+LEASE_TTL_SECONDS: Final = 60 * 60
 PROMOTER: Final = Path(__file__).resolve().with_name("lease_promote.py")
 PENDING_DIRECTORY: Final = "mosaic-lease"
 LOCK_FILE: Final = "promotion.lock"
+RESULT_FILE: Final = "last-result.json"
 TERMINAL_FAILURE_CODES: Final = frozenset(
     {
         "RECEIPT_REPLAY",
@@ -145,6 +148,54 @@ def read_pending(directory_descriptor: int, name: str) -> PendingChallenge | Non
     return PendingChallenge(challenge, metadata.st_dev, metadata.st_ino)
 
 
+def write_result(
+    directory_descriptor: int,
+    attempt_id: str,
+    verified: bool,
+    reason: str | None,
+    session_id: str,
+    wall_clock: float,
+) -> None:
+    result = {
+        "attempt_id": attempt_id,
+        "expires_at_wallclock": wall_clock + LEASE_TTL_SECONDS if verified else None,
+        "reason": reason,
+        "session_id": session_id,
+        "ts": wall_clock,
+        "verified": verified,
+    }
+    temporary = f".{RESULT_FILE}.tmp-{secrets.token_hex(8)}"
+    flags = (
+        os.O_WRONLY
+        | os.O_CREAT
+        | os.O_EXCL
+        | getattr(os, "O_CLOEXEC", 0)
+        | getattr(os, "O_NOFOLLOW", 0)
+    )
+    descriptor = os.open(temporary, flags, 0o600, dir_fd=directory_descriptor)
+    try:
+        os.fchmod(descriptor, 0o600)
+        with os.fdopen(descriptor, "w", encoding="utf-8", closefd=False) as stream:
+            json.dump(result, stream, separators=(",", ":"), sort_keys=True)
+            stream.flush()
+            os.fsync(stream.fileno())
+        os.replace(
+            temporary,
+            RESULT_FILE,
+            src_dir_fd=directory_descriptor,
+            dst_dir_fd=directory_descriptor,
+        )
+        os.fsync(directory_descriptor)
+    except Exception:
+        try:
+            os.unlink(temporary, dir_fd=directory_descriptor)
+        except FileNotFoundError:
+            pass
+        raise
+    finally:
+        os.close(descriptor)
+
+
 def delete_pending_if_unchanged(
     directory_descriptor: int,
     name: str,
@@ -233,6 +284,7 @@ def main(
     environ: Mapping[str, str] | None = None,
     stderr: TextIO | None = None,
     run: Callable[..., subprocess.CompletedProcess[str]] = subprocess.run,
+    now: Callable[[], float] = time.time,
 ) -> int:
     source_environment = os.environ if environ is None else environ
     error_stream = sys.stderr if stderr is None else stderr
@@ -241,6 +293,7 @@ def main(
 
     try:
         runtime_dir, pending_name = session_pending_name(source_environment)
+        session_id = source_environment["MOSAIC_LEASE_SESSION_ID"]
         directory_descriptor = open_pending_directory(runtime_dir)
         if directory_descriptor is None:
             return 0
@@ -270,6 +323,7 @@ def main(
         )
         reply = parse_reply(completed)
         if reply is not None and reply.get("ok") is True:
+            write_result(directory_descriptor, pending.value, True, None, session_id, now())
             delete_pending_if_unchanged(
                 directory_descriptor,
                 pending_name,
@@ -283,6 +337,7 @@ def main(
             code = str(reply["code"])
             print(f"Mosaic promotion incomplete: {code}.", file=error_stream)
             if code in TERMINAL_FAILURE_CODES:
+                write_result(directory_descriptor, pending.value, False, code, session_id, now())
                 delete_pending_if_unchanged(
                     directory_descriptor,
                     pending_name,