feat: add health monitoring endpoint

apps/health/views.py

@@ -0,0 +1,42 @@
+from __future__ import annotations
+
+import os
+from collections.abc import Mapping
+from datetime import UTC, datetime
+from typing import cast
+
+from django.http import JsonResponse
+from django.views.decorators.cache import never_cache
+
+from apps.health.checks import check_backup, check_cache, check_celery, check_db
+
+CRITICAL_CHECKS = {"db", "cache"}
+
+
+@never_cache
+def health_view(request):
+    checks: dict[str, Mapping[str, object]] = {
+        "db": check_db(),
+        "cache": check_cache(),
+        "celery": check_celery(),
+        "backup": check_backup(),
+    }
+
+    if any(cast(str, checks[name]["status"]) == "fail" for name in CRITICAL_CHECKS):
+        overall_status = "unhealthy"
+    elif any(cast(str, check["status"]) == "fail" for check in checks.values()):
+        overall_status = "degraded"
+    else:
+        overall_status = "ok"
+
+    payload = {
+        "status": overall_status,
+        "version": {
+            "git_sha": os.environ.get("GIT_SHA", "unknown"),
+            "build": os.environ.get("BUILD_ID", "unknown"),
+        },
+        "checks": checks,
+        "timestamp": datetime.now(UTC).strftime("%Y-%m-%dT%H:%M:%SZ"),
+    }
+    response_status = 503 if overall_status == "unhealthy" else 200
+    return JsonResponse(payload, status=response_status)