lmxopcua/src/Server/ZB.MOM.WW.OtOpcUa.Host/Health/HealthEndpoints.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Diagnostics.HealthChecks;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Diagnostics.HealthChecks;

namespace ZB.MOM.WW.OtOpcUa.Host.Health;

public static class HealthEndpoints
{
    /// <summary>
    /// Registers the standard ASP.NET Core health-check infrastructure plus the OtOpcUa-specific
    /// probes. Mirrors ScadaLink's three-tier pattern: <c>ready</c> = boot ok; <c>active</c> =
    /// fully serving traffic; <c>healthz</c> = bare process liveness.
    /// </summary>
    public static IServiceCollection AddOtOpcUaHealth(this IServiceCollection services)
    {
        services.AddHealthChecks()
            .AddCheck<DatabaseHealthCheck>("configdb", tags: new[] { "ready", "active" })
            .AddCheck<AkkaClusterHealthCheck>("akka", tags: new[] { "ready", "active" })
            .AddCheck<AdminRoleLeaderHealthCheck>("admin-leader", tags: new[] { "active" });
        return services;
    }

    public static IEndpointRouteBuilder MapOtOpcUaHealth(this IEndpointRouteBuilder app)
    {
        // AllowAnonymous on all three — Traefik / k8s liveness probes / load-balancers
        // hit these without credentials. Without it the AddOtOpcUaAuth fallback policy
        // 401s every probe and Traefik marks every backend unhealthy.
        app.MapHealthChecks("/health/ready", new HealthCheckOptions
        {
            Predicate = c => c.Tags.Contains("ready"),
        }).AllowAnonymous();
        app.MapHealthChecks("/health/active", new HealthCheckOptions
        {
            Predicate = c => c.Tags.Contains("active"),
        }).AllowAnonymous();
        app.MapHealthChecks("/healthz", new HealthCheckOptions
        {
            Predicate = _ => false, // process-liveness only — no probes run.
        }).AllowAnonymous();
        return app;
    }
}