List before watching, so an empty cluster counts as synced

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "slo-api"
-version = "0.2.0"
+version = "0.2.1"
 description = "HTTP facade for LLMSLORequirement CRs — exposes route-keyed REST API, translates to/from CRD specs"
 requires-python = ">=3.10"
 readme = "README.md"

src/slo_api/cr_index.py

@@ -118,9 +118,20 @@ def _run(self):
 
     def _watch_once(self):
         api = self._api_client()
+        # List first, then watch from the list's resourceVersion. A bare watch only marks the index
+        # synced on its first event, and with no CRs in the cluster there is none: the API server
+        # sends no ADDED event and its first BOOKMARK can take minutes, so readiness stayed 503 and
+        # the liveness probe killed the pod before it ever served. An empty list is a complete one.
+        listing = api.list_cluster_custom_object(group(), VERSION, PLURAL)
+        self._replace((listing or {}).get("items") or [])
+        self._synced.set()
+        rv = ((listing or {}).get("metadata") or {}).get("resourceVersion")
+
         wf = self._watch_factory or watch.Watch
         w = wf()
         kwargs = {} if self._watch_factory else {"allow_watch_bookmarks": True}
+        if rv and not self._watch_factory:
+            kwargs["resource_version"] = rv
         try:
             for event in w.stream(
                     api.list_cluster_custom_object,
@@ -142,6 +153,25 @@ def _watch_once(self):
             if callable(stop):
                 stop()
 
+    def _replace(self, items):
+        """Rebuild the index from a full list: drops CRs deleted while no watch was running.
+
+        Built aside and swapped in under the lock, so a reader sees the old index or the new one,
+        never the empty or half-built one in between -- this runs on every watch reconnect."""
+        by_key, by_service = {}, {}
+        for cr in items:
+            meta = cr.get("metadata") or {}
+            ns, name = meta.get("namespace"), meta.get("name")
+            if not ns or not name:
+                continue
+            sid = (cr.get("spec") or {}).get("serviceId") or ""
+            by_key[(ns, name)] = cr
+            lst = by_service.setdefault(sid, [])
+            if (ns, name) not in lst:
+                lst.append((ns, name))
+        with self._lock:
+            self._by_key, self._by_service = by_key, by_service
+
     def _apply(self, etype, cr):
         meta = cr.get("metadata") or {}
         spec = cr.get("spec") or {}

tests/test_cr_index_sync.py

@@ -0,0 +1,70 @@
+import threading
+
+from slo_api.cr_index import CRIndex
+
+from conftest import CRD_TEMPLATE, FakeCustomObjectsApi
+
+
+class SilentWatch:
+    """A watch the way a real API server answers one on an empty cluster: no ADDED events and no
+    BOOKMARK for a long while. (FakeWatch in conftest always sends a BOOKMARK, which is why the
+    tests never saw an index that could not get synced.)"""
+
+    def __init__(self, stop):
+        self._stop = stop
+
+    def stream(self, fn, *args, **kwargs):
+        while not self._stop.is_set():
+            self._stop.wait(0.01)
+        return
+        yield  # pragma: no cover -- makes this a generator
+
+    def stop(self):
+        pass
+
+
+def _index(api):
+    idx = CRIndex(api=api, watch_factory=lambda: SilentWatch(idx._stop))
+    return idx
+
+
+def test_empty_cluster_is_synced():
+    idx = _index(FakeCustomObjectsApi())
+    idx.start()
+    try:
+        assert idx.wait_synced(timeout=2), "an empty list is complete: the index must report synced"
+        assert idx.list_routes() == []
+    finally:
+        idx.stop()
+
+
+def test_list_fills_the_index_before_any_watch_event():
+    api = FakeCustomObjectsApi()
+    api.seed(CRD_TEMPLATE("ns1", "a", "route-a"))
+    api.seed(CRD_TEMPLATE("ns2", "b", "route-b"))
+    idx = _index(api)
+    idx.start()
+    try:
+        assert idx.wait_synced(timeout=2)
+        assert idx.list_routes() == ["route-a", "route-b"]
+    finally:
+        idx.stop()
+
+
+def test_relist_never_shows_an_empty_index():
+    """A watch reconnect re-lists and rebuilds the index. Readers in between must keep seeing the
+    old index, not a cleared or half-built one."""
+    api = FakeCustomObjectsApi()
+    old = [CRD_TEMPLATE("ns1", "a", "route-a"), CRD_TEMPLATE("ns2", "b", "route-b")]
+    idx = _index(api)
+    idx._replace(old)
+    seen = []
+
+    def relisted():
+        for cr in old + [CRD_TEMPLATE("ns3", "c", "route-c")]:
+            seen.append(idx.list_routes())   # what a reader sees while the rebuild is under way
+            yield cr
+
+    idx._replace(relisted())
+    assert all(s == ["route-a", "route-b"] for s in seen), seen
+    assert idx.list_routes() == ["route-a", "route-b", "route-c"]