Cortside.Health

Framework for exposing health check endpoint with configurable checks and ability to publish availablity via telemetry recorder.

Example appsettings.json configuration

"HealthCheckHostedService": {
    "Name": "{{Service:Name}}",
    "Enabled": true,
    "Interval": 5,
    "CacheDuration": 30,
    "Checks": [
        {
            "Name": "webapistarter-db",
            "Type": "dbcontext",
            "Required": true,
            "Interval": 30,
            "Timeout": 5
        },
        {
            "Name": "policyserver",
            "Type": "url",
            "Required": false,
            "Value": "{{PolicyServer:PolicyServerUrl}}/health",
            "Interval": 30,
            "Timeout": 5
        },
        {
            "Name": "identityserver",
            "Type": "url",
            "Required": false,
            "Value": "{{IdentityServer:Authority}}/api/health",
            "Interval": 30,
            "Timeout": 5
        }
    ]
},
"ApplicationInsights": {
    "InstrumentationKey": "",
    "EndpointAddress": "https://dc.services.visualstudio.com/v2/track"
}

Example build.json (or at part of appsettings.json)

"Build": {
    "version": "1.0.0",
    "timestamp": "2022-01-27 22:51:58Z",
    "tag": "1.0-local",
    "suffix": "local"
}

Note: you can use the {{property}} syntax in the name and value properties of the check to reference a configuration property elsewhere in configuration. This way you are not duplicating values, example for services that have another section so that you don't have mismatch in check and running value.

Example Startup.cs configuration

// use PartManager to register controller -- add to existing AddControllers call
services.AddControllers()
    .PartManager.ApplicationParts.Add(new AssemblyPart(typeof(HealthController).Assembly));

// health checks
// telemetry recorder
string instrumentationKey = Configuration["ApplicationInsights:InstrumentationKey"];
string endpointAddress = Configuration["ApplicationInsights:EndpointAddress"];
if (!string.IsNullOrEmpty(instrumentationKey) && !string.IsNullOrEmpty(endpointAddress)) {
    TelemetryConfiguration telemetryConfiguration = new TelemetryConfiguration(instrumentationKey, new InMemoryChannel { EndpointAddress = endpointAddress });
    TelemetryClient telemetryClient = new TelemetryClient(telemetryConfiguration);
    services.AddSingleton(telemetryClient);
    services.AddTransient<IAvailabilityRecorder, ApplicationInsightsRecorder>();
} else {
    services.AddTransient<IAvailabilityRecorder, NullRecorder>();
}

// configuration
services.AddSingleton(Configuration.GetSection("HealthCheckHostedService").Get<HealthCheckServiceConfiguration>());
services.AddSingleton(Configuration.GetSection("Build").Get<BuildModel>());

// checks
services.AddTransient<UrlCheck>();
services.AddTransient<DbContextCheck>();

// check factory and hosted service
services.AddTransient<ICheckFactory, CheckFactory>();
services.AddHostedService<HealthCheckHostedService>();

// for DbContextCheck
services.AddTransient<DbContext, DatabaseContext>();

Example Startup.cs configuration using extension method

ServiceCollection extension methods are also available to setup more simply:

The IConfiguration oject is expect to be loaded with secions of the following names HealthCheckHostedService, ApplicationInsights, and Build to successfully register health services.

// add health services
services.AddHealth(o => {
    o.UseConfiguration(Configuration);
    o.AddCustomCheck("example", typeof(ExampleCheck));
});

Running example

See Coeus as a working example of full api service that make use of health checks at https://github.com/cortside/coeus/shoppingcart-api. A template api project is also available at https://github.com/cortside/cortside.templates.