Remove the image build and consolidate operational code under scripts

scripts/provisioning/state.py

@@ -0,0 +1,37 @@
+"""Serialize host configuration changes across provisioning commands."""
+import contextlib
+import fcntl
+import os
+from pathlib import Path
+import stat
+
+
+class ProvisionError(RuntimeError):
+    pass
+
+
+def safe_path(path):
+    path = Path(path).absolute()
+    for part in (*reversed(path.parents), path):
+        try:
+            info = part.lstat()
+        except FileNotFoundError:
+            continue
+        if stat.S_ISLNK(info.st_mode):
+            raise ProvisionError('managed path contains a symbolic link')
+    return path
+
+
+@contextlib.contextmanager
+def exclusive_lock(path):
+    path = safe_path(path)
+    path.parent.mkdir(parents=True, exist_ok=True)
+    fd = os.open(path, os.O_CREAT | os.O_RDWR | os.O_NOFOLLOW, 0o600)
+    try:
+        try:
+            fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
+        except BlockingIOError:
+            raise ProvisionError('another initialization is running; inspect status before retrying') from None
+        yield
+    finally:
+        os.close(fd)