C#•2y ago

✅ Supporting multiple routes for health checks in asp.net core

I have a couple monitoring systems that need are calling some api's and I need to support different response types for each monitoring system. Is there a way in asp.net core? Assume I have a number of health probes, for example...

.AddHealthCheck<Db2HealthCheck>()
.AddHealthCheck<SqlHealthCheck>()
.AddHealthCheck<DynamoHealthCheck>()
.AddHealthCheck<CognitoHealthCheck>()
.AddHealthCheck<YadaYadaYada>()

The yadayadayada monitor should only check the YadaYadaYada health check, for example
The Aws monitor should only check the CognitoHealthCheck
The database monitor should oinly check Db2, Dynamo, and SqlHealthCheck

TeBeCo•1/30/24, 6:20 PM

i don't get the question there

TeBeCo•1/30/24, 6:20 PM

will add an IHealthCheck in an List<IHealthCheck>

TeBeCo•1/30/24, 6:20 PM

up to you to implement the check itself

TeBeCo•1/30/24, 6:20 PM

there's no route or no nothing no where

TeBeCo•1/30/24, 6:21 PM

then you have .MapHealthCheck + url that can be added to the app to expose healthcheck results

TeBeCo•1/30/24, 6:21 PM

and given how poorly things are designed, calling that route will call all healcheck to check

TeBeCo•1/30/24, 6:21 PM

which is a receipe for cascade failure disaster

TeBeCo•1/30/24, 6:22 PM

then comes in the healcheck Publisher

TeBeCo•1/30/24, 6:22 PM

which you could eventually use to public these results somewhere

TeBeCo•1/30/24, 6:22 PM

like publish to an external system

TeBeCo•1/30/24, 6:22 PM

or in memory

TeBeCo•1/30/24, 6:22 PM

now what can be done is adding multiple time the MapHealthCheck with various URI

TeBeCo•1/30/24, 6:23 PM

and in each have some logic to get the results

TeBeCo•1/30/24, 6:23 PM

each healthcheck can have Tags for example

TeBeCo•1/30/24, 6:23 PM

so you could use LINQ on name / type / tags etc ....

TeBeCo•1/30/24, 6:24 PM

sooooo recap:

TeBeCo•1/30/24, 6:25 PM

each of your impl like will have it own dedicated code you write for that dedicated check
Healthcheck can have tags
all result are forced by aspnetcore but can contain data of yours inside and others
if you need to push/publish the result elsewhere you can use or code custom Health publisher
you can add as many endpoint as you want + logic to expose results

Mayor McCheeseOP•1/30/24, 6:25 PM

now what can be done is adding multiple time the MapHealthCheck with various URI
and in each have some logic to get the results
each healthcheck can have Tags for example
so you could use LINQ on name / type / tags etc ....

This is the part I wasn't certain of

TeBeCo•1/30/24, 6:26 PM

1 sec

Mayor McCheeseOP•1/30/24, 6:26 PM

I've done the one health check endpoint before

TeBeCo•1/30/24, 6:30 PM

TeBeCo•1/30/24, 6:35 PM

extension in case you find horrible the API being forced horribly and not DI friendly AT ALL:

TeBeCo•1/30/24, 6:35 PM

you can increated TDep1, TDep2 etc ..... after

TeBeCo•1/30/24, 6:35 PM

right now aspnetcore healthcheck is an huge anti pattern mess for DI

TeBeCo•1/30/24, 6:36 PM

so if you want to add multiple HC based on the same type with different name you're fucked

TeBeCo•1/30/24, 6:36 PM

these solves that

TeBeCo•1/30/24, 6:36 PM

it's because all check are ... NOT IN FUCKING DI

TeBeCo•1/30/24, 6:36 PM

they are in a List<T> inside a massive huge IOption that is Healthchecksoptions

TeBeCo•1/30/24, 6:37 PM

which you have to mutate or hackaround with a PostConfigure

Mayor McCheeseOP•1/30/24, 6:37 PM

Thanks @TeBeCo this is exactly what I need

TeBeCo•1/30/24, 6:37 PM

here is how i'm using it:

TeBeCo•1/30/24, 6:38 PM

DistributedCacheOptions: mine with all redis settings

TeBeCo•1/30/24, 6:38 PM

AddOptions<RedisCacheOptions> => the official RedisCach stackexchange extension options for aspentcore

TeBeCo•1/30/24, 6:39 PM

<== consume their RedisCacheOptions

Mayor McCheeseOP•1/30/24, 6:39 PM

I follow a similar pattern for adding some other depdendencies, I like adding the health check there.

TeBeCo•1/30/24, 6:39 PM

is my extension from above

Mayor McCheeseOP•1/30/24, 6:40 PM

it's buttoned up nicely that way without a giant wall of DI text

TeBeCo•1/30/24, 6:40 PM

but now I can all make these rely on

TeBeCo•1/30/24, 6:40 PM

this is in a core nuget package for all api

TeBeCo•1/30/24, 6:40 PM

api just do which internally just do

TeBeCo•1/30/24, 6:41 PM

and app can .Configure/PostConfigure the since everything under it rely on this source of truth

TeBeCo•1/30/24, 6:41 PM

the only neat missing here ... is

TeBeCo•1/30/24, 6:41 PM

AddStackExchangeRedisCache should be change to have a ConnecitonMultiplexer manually created and used inside the empty lambda

TeBeCo•1/30/24, 6:42 PM

and then add a call to AddTelemetry etc .... with that multiplexer/connection

Mayor McCheeseOP•1/30/24, 7:24 PM

Thanks again

using Microsoft.Extensions.DependencyInjection.Extensions; using Microsoft.Extensions.Diagnostics.HealthChecks; namespace Microsoft.Extensions.DependencyInjection; public static class HealthChecksBuilderExtensions { public static IHealthChecksBuilder AddHealthCheckRegistration<T>(this IHealthChecksBuilder builder) where T : class, IHealthCheck => builder.AddHealthCheckRegistration<T>(string.Empty); public static IHealthChecksBuilder AddHealthCheckRegistration<T>(this IHealthChecksBuilder builder, Action<HealthCheckRegistration> configure) where T : class, IHealthCheck => builder.AddHealthCheckRegistration<T>(string.Empty, configure); public static IHealthChecksBuilder AddHealthCheckRegistration<T, TDep1>(this IHealthChecksBuilder builder, Action<HealthCheckRegistration, TDep1> configure) where T : class, IHealthCheck where TDep1 : class => builder.AddHealthCheckRegistration<T, TDep1>(string.Empty, configure); public static IHealthChecksBuilder AddHealthCheckRegistration<T>(this IHealthChecksBuilder builder, string name) where T : class, IHealthCheck { var factory = () => new HealthCheckRegistration(name, GetServiceOrCreateInstance, null, null, null); return builder.AddHealthCheckRegistration<T>(factory); static T GetServiceOrCreateInstance(IServiceProvider serviceProvider) => ActivatorUtilities.GetServiceOrCreateInstance<T>(serviceProvider); } public static IHealthChecksBuilder AddHealthCheckRegistration<T>(this IHealthChecksBuilder builder, string name, Action<HealthCheckRegistration> configure) where T : class, IHealthCheck { var factory = () => { var registration = new HealthCheckRegistration(name, GetServiceOrCreateInstance, null, null, null); configure(registration); return registration; }; return builder.AddHealthCheckRegistration<T>(factory); static T GetServiceOrCreateInstance(IServiceProvider serviceProvider) => ActivatorUtilities.GetServiceOrCreateInstance<T>(serviceProvider); } public static IHealthChecksBuilder AddHealthCheckRegistration<T, TDep1>(this IHealthChecksBuilder builder, string name, Action<HealthCheckRegistration, TDep1> configure) where T : class, IHealthCheck where TDep1 : class { var factory = (TDep1 dep1) => { var registration = new HealthCheckRegistration(name, GetServiceOrCreateInstance, null, null, null); configure(registration, dep1); return registration; }; return builder.AddHealthCheckRegistration<T, TDep1>(factory); static T GetServiceOrCreateInstance(IServiceProvider serviceProvider) => ActivatorUtilities.GetServiceOrCreateInstance<T>(serviceProvider); } public static IHealthChecksBuilder AddHealthCheckRegistration<T>(this IHealthChecksBuilder builder, Func<HealthCheckRegistration> factory) where T : class, IHealthCheck { builder.Services.TryAddTransient<T>(); builder.Services .AddOptions<HealthCheckServiceOptions>() .PostConfigure(options => { options.Registrations.Add(factory()); }); return builder; } public static IHealthChecksBuilder AddHealthCheckRegistration<T, TDep1>(this IHealthChecksBuilder builder, Func<TDep1, HealthCheckRegistration> factory) where T : class, IHealthCheck where TDep1 : class { builder.Services.TryAddTransient<T>(); builder.Services .AddOptions<HealthCheckServiceOptions>() .PostConfigure<TDep1>((options, dep1) => { options.Registrations.Add(factory(dep1)); }); return builder; } }