feat(api): add feature-flagged /rest/v1/health endpoint (#936)

* feat(api): add feature-flagged /rest/v1/health endpoint

Adds a lightweight deploy/uptime health probe at GET /rest/v1/health, gated behind the CRE_ENABLE_HEALTH feature flag (off by default).

Behavior:
- Flag off (default): endpoint returns 404, as if it does not exist.
- Flag on, healthy: 200 with {ok, db_reachable, cre_count, standards_count} when the serving DB is reachable and holds a non-empty dataset.
- Flag on, unhealthy: 503 when the DB is unreachable or the dataset is empty/broken (reason explains which).

Node_collection.health_check() runs cheap COUNT queries over CRE and Node, never raises (connectivity errors are reported as ok=False), and treats a zero count for either as an empty dataset.

Scope is intentionally limited to DB reachability + data sanity. Deeper checks (gap-analysis completeness, mapping coverage, Neo4j, Redis) are deliberately excluded by design and belong in ops tooling.

* fix: load .env in feature_flags and document CRE_ENABLE_HEALTH flag

* Modified the .env issue

Author: skypank-coder

.env.example

@@ -24,6 +24,13 @@ REDIS_NO_SSL=false
 FLASK_CONFIG=development
 INSECURE_REQUESTS=false
 
+# Feature Flags
+# Enable the deploy/uptime health probe at GET /rest/v1/health.
+# Set to one of 1, true, yes (case-insensitive) to enable; any other value
+# (including unset or false) leaves it off and the endpoint returns 404.
+
+CRE_ENABLE_HEALTH=false
+
 # Embeddings
 
 NO_GEN_EMBEDDINGS=false

README.md

@@ -289,6 +289,7 @@ Then edit `.env` and provide values appropriate for your environment.
 * Google Auth: `GOOGLE_CLIENT_ID`, `GOOGLE_CLIENT_SECRET`, `GOOGLE_SECRET_JSON`, `LOGIN_ALLOWED_DOMAINS`
 * GCP: `GCP_NATIVE`
 * Spreadsheet Auth: `OpenCRE_gspread_Auth`
+* Feature flags: `CRE_ENABLE_HEALTH` (enable the `GET /rest/v1/health` deploy/uptime probe; off by default, returns 404 when unset)
 
 See `.env.example` for full list and defaults.
 

application/database/db.py

@@ -2264,6 +2264,54 @@ def get_root_cres(self):
         )
         return self._hydrate_cres_batch(list(cres))
 
+    def health_check(self) -> Dict[str, Any]:
+        """Lightweight liveness/readiness probe for the serving database.
+
+        Intended for use by a deploy/uptime health endpoint, NOT for deep
+        operational checks (GA completeness, mapping coverage, etc.) which are
+        slow and belong in ops tooling. Performs cheap COUNT queries and never
+        raises: connectivity failures are reported as ``ok=False`` so the caller
+        can return an appropriate status code.
+
+        Returns a dict with:
+          - ``ok``: True only if the DB is reachable AND holds a non-empty
+            dataset (at least one CRE and one standard/node).
+          - ``db_reachable``: True if the COUNT queries executed.
+          - ``cre_count`` / ``standards_count``: populated when reachable.
+          - ``reason``: short human-readable explanation when ``ok`` is False.
+        """
+        try:
+            cre_count = self.session.query(func.count(CRE.id)).scalar() or 0
+            standards_count = self.session.query(func.count(Node.id)).scalar() or 0
+        except OperationalError:
+            return {
+                "ok": False,
+                "db_reachable": False,
+                "reason": "database unreachable",
+            }
+        except Exception:  # pragma: no cover - defensive, never fail open
+            return {
+                "ok": False,
+                "db_reachable": False,
+                "reason": "database health query failed",
+            }
+
+        if cre_count == 0 or standards_count == 0:
+            return {
+                "ok": False,
+                "db_reachable": True,
+                "cre_count": cre_count,
+                "standards_count": standards_count,
+                "reason": "empty dataset",
+            }
+
+        return {
+            "ok": True,
+            "db_reachable": True,
+            "cre_count": cre_count,
+            "standards_count": standards_count,
+        }
+
     def get_embeddings_by_doc_type(self, doc_type: str) -> Dict[str, List[float]]:
         res = {}
         embeddings = (

application/feature_flags.py

@@ -1,7 +1,18 @@
 import os
 
+try:
+    from dotenv import load_dotenv  # type: ignore
+
+    load_dotenv()
+except ImportError:
+    pass
+
 TRUE_VALUES = {"1", "true", "yes"}
 
 
 def is_cre_import_allowed() -> bool:
     return os.getenv("CRE_ALLOW_IMPORT", "").strip().lower() in TRUE_VALUES
+
+
+def is_health_endpoint_enabled() -> bool:
+    return os.getenv("CRE_ENABLE_HEALTH", "").strip().lower() in TRUE_VALUES

application/tests/web_main_test.py

@@ -1360,3 +1360,66 @@ def test_get_cre_csv(self) -> None:
                 data.getvalue(),
                 response.data.decode(),
             )
+
+    def test_health_disabled_by_default_returns_404(self) -> None:
+        os.environ.pop("CRE_ENABLE_HEALTH", None)
+        with self.app.test_client() as client:
+            response = client.get("/rest/v1/health")
+            self.assertEqual(404, response.status_code)
+
+    def test_health_enabled_empty_dataset_returns_503(self) -> None:
+        os.environ["CRE_ENABLE_HEALTH"] = "1"
+        try:
+            with self.app.test_client() as client:
+                response = client.get("/rest/v1/health")
+                self.assertEqual(503, response.status_code)
+                body = json.loads(response.data.decode())
+                self.assertFalse(body["ok"])
+                self.assertTrue(body["db_reachable"])
+                self.assertEqual("empty dataset", body["reason"])
+        finally:
+            os.environ.pop("CRE_ENABLE_HEALTH", None)
+
+    def test_health_enabled_populated_returns_200(self) -> None:
+        os.environ["CRE_ENABLE_HEALTH"] = "1"
+        try:
+            collection = db.Node_collection()
+            collection.add_cre(
+                defs.CRE(id="111-115", description="CA", name="CA", tags=["ta"])
+            )
+            collection.add_node(
+                defs.Standard(
+                    name="s1", section="s11", subsection="s111", version="1.1.1"
+                )
+            )
+            with self.app.test_client() as client:
+                response = client.get("/rest/v1/health")
+                self.assertEqual(200, response.status_code)
+                body = json.loads(response.data.decode())
+                self.assertTrue(body["ok"])
+                self.assertTrue(body["db_reachable"])
+                self.assertGreaterEqual(body["cre_count"], 1)
+                self.assertGreaterEqual(body["standards_count"], 1)
+        finally:
+            os.environ.pop("CRE_ENABLE_HEALTH", None)
+
+    def test_health_db_unreachable_returns_503(self) -> None:
+        os.environ["CRE_ENABLE_HEALTH"] = "1"
+        try:
+            with patch.object(
+                db.Node_collection,
+                "health_check",
+                return_value={
+                    "ok": False,
+                    "db_reachable": False,
+                    "reason": "database unreachable",
+                },
+            ):
+                with self.app.test_client() as client:
+                    response = client.get("/rest/v1/health")
+                    self.assertEqual(503, response.status_code)
+                    body = json.loads(response.data.decode())
+                    self.assertFalse(body["ok"])
+                    self.assertFalse(body["db_reachable"])
+        finally:
+            os.environ.pop("CRE_ENABLE_HEALTH", None)

application/web/web_main.py

@@ -22,7 +22,7 @@
 from application.cmd import cre_main
 from application.defs import cre_defs as defs
 from application.defs import cre_exceptions
-from application.feature_flags import is_cre_import_allowed
+from application.feature_flags import is_cre_import_allowed, is_health_endpoint_enabled
 
 from application.utils import spreadsheet as sheet_utils
 from application.utils import mdutils, redirectors, gap_analysis
@@ -584,6 +584,27 @@ def text_search() -> Any:
         abort(404, "No object matches the given search terms")
 
 
+@app.route("/rest/v1/health", methods=["GET"])
+def health() -> Any:
+    """Deploy/uptime health probe (feature-flagged, off by default).
+
+    Enable with CRE_ENABLE_HEALTH=1. Scope is intentionally narrow and fast so
+    it can gate deploys without failing for the wrong reason:
+      - 200: app up, serving DB reachable, dataset non-empty (CREs and
+        standards present).
+      - 503: DB unreachable or dataset empty/broken.
+    Deeper checks (gap-analysis completeness, mapping coverage, Neo4j/Redis)
+    are deliberately excluded and live in ops tooling instead.
+    """
+    if not is_health_endpoint_enabled():
+        abort(404)
+
+    database = db.Node_collection()
+    result = database.health_check()
+    status_code = 200 if result.get("ok") else 503
+    return jsonify(result), status_code
+
+
 @app.route("/rest/v1/root_cres", methods=["GET"])
 def find_root_cres() -> Any:
     """