initial commit. phase 1 complete

backend/apps/health/views.py

@@ -0,0 +1,74 @@
+"""
+Health check endpoint required by the docker-compose web service healthcheck:
+  test: ["CMD-SHELL", "curl -fs http://localhost:8000/api/health/ || exit 1"]
+
+Does NOT require authentication — the docker daemon calls this, not users.
+Returns HTTP 200 when all services are healthy, HTTP 503 on any failure.
+"""
+
+import logging
+
+from django.core.cache import cache
+from django.db import OperationalError, connection
+from django.http import JsonResponse
+from django.views import View
+
+logger = logging.getLogger(__name__)
+
+VERSION = "1.0.0"
+
+
+class HealthCheckView(View):
+    """
+    Synchronous health check for web, database, and Redis.
+
+    Response body:
+      {
+        "status": "ok" | "degraded",
+        "version": "1.0.0",
+        "services": {
+          "database": "ok" | "error",
+          "redis": "ok" | "error"
+        }
+      }
+    """
+
+    def get(self, request) -> JsonResponse:  # type: ignore[override]
+        db_status = _check_database()
+        redis_status = _check_redis()
+
+        all_ok = db_status == "ok" and redis_status == "ok"
+        http_status = 200 if all_ok else 503
+
+        return JsonResponse(
+            {
+                "status": "ok" if all_ok else "degraded",
+                "version": VERSION,
+                "services": {
+                    "database": db_status,
+                    "redis": redis_status,
+                },
+            },
+            status=http_status,
+        )
+
+
+def _check_database() -> str:
+    try:
+        with connection.cursor() as cursor:
+            cursor.execute("SELECT 1")
+        return "ok"
+    except OperationalError:
+        logger.exception("Database health check failed")
+        return "error"
+
+
+def _check_redis() -> str:
+    try:
+        cache.set("_health_check", "1", timeout=5)
+        if cache.get("_health_check") != "1":
+            raise RuntimeError("Redis round-trip failed")
+        return "ok"
+    except Exception:
+        logger.exception("Redis health check failed")
+        return "error"