Switch to using ULIDs for context_ids (#70246)

homeassistant/core.py

@@ -72,7 +72,7 @@ from .exceptions import (
     ServiceNotFound,
     Unauthorized,
 )
-from .util import dt as dt_util, location, uuid as uuid_util
+from .util import dt as dt_util, location, ulid as ulid_util
 from .util.async_ import (
     fire_coroutine_threadsafe,
     run_callback_threadsafe,
@@ -696,7 +696,7 @@ class Context:
 
     user_id: str | None = attr.ib(default=None)
     parent_id: str | None = attr.ib(default=None)
-    id: str = attr.ib(factory=uuid_util.random_uuid_hex)
+    id: str = attr.ib(factory=ulid_util.ulid_hex)
 
     def as_dict(self) -> dict[str, str | None]:
         """Return a dictionary representation of the context."""

homeassistant/util/ulid.py

@@ -0,0 +1,25 @@
+"""Helpers to generate ulids."""
+
+from random import getrandbits
+import time
+
+
+# In the future once we require python 3.10 and above, we can
+# create a new function that uses base64.b32encodehex to shorten
+# these to 26 characters.
+def ulid_hex() -> str:
+    """Generate a ULID in hex that will work for a UUID.
+
+    This ulid should not be used for cryptographically secure
+    operations.
+
+     01AN4Z07BY      79KA1307SR9X4MV3
+    |----------|    |----------------|
+     Timestamp          Randomness
+       48bits             80bits
+
+    This string can be converted with https://github.com/ahawker/ulid
+
+    ulid.from_uuid(uuid.UUID(value))
+    """
+    return f"{int(time.time()*1000):012x}{getrandbits(80):020x}"

tests/util/test_ulid.py

@@ -0,0 +1,11 @@
+"""Test Home Assistant ulid util methods."""
+
+import uuid
+
+import homeassistant.util.ulid as ulid_util
+
+
+async def test_ulid_util_uuid_hex():
+    """Verify we can generate a ulid."""
+    assert len(ulid_util.ulid_hex()) == 32
+    assert uuid.UUID(ulid_util.ulid_hex())