Akka.Cluster HTTP HealthCheck

HomeController.cs

public class HomeController : Controller
    {
        private readonly Cluster _cluster;

        public HomeController()
        {
            _cluster = Cluster.Get(SystemActors.ActorSystem);
        }

        public IActionResult Index()
        {
            return View();
        }

        public IActionResult HealthCheck()
        {
            var state = _cluster.State;
            var atLeastOneAvailableLighthouse = state.Members
                .Any(x => x.HasRole("lighthouse") 
                          && x.Status == MemberStatus.Up 
                          && !state.Unreachable.Contains(x));

            var statusCode = atLeastOneAvailableLighthouse
                ? HttpStatusCode.OK
                : HttpStatusCode.InternalServerError;

            var sb = new StringBuilder();
            sb.AppendLine("Members: ");
            foreach (var member in state.Members)
            {
                sb.AppendFormat("{0}[{1}] Roles=[{2}], Reachable={3}", member.Address, member.Status,
                    string.Join(",", member.Roles), !state.Unreachable.Contains(member));
                sb.AppendLine();
            }

            return new ContentResult()
            {
                Content = sb.ToString(),
                StatusCode = (int) statusCode
            };
        }
    }

Basic internal HTTP healthcheck for determining if we're in a joinable cluster, via the "at least one reachable lighthouse node is a current member of the cluster" rule