Rocket.Libraries.ConsulHelper

Dead simple .Net library to register services to Consul and to query Consul for registered services.

Quick Start

Installation

Grab the nuget package from https://www.nuget.org/packages/Rocket.Libraries.ConsulHelper/

1. Config File

{
  "ConsulSettings": {
    "Name": "ConsulHelper.Example.App1",
    "Port": 5113,
    "ConsulUrl": "http://localhost:8500",
    "Address": "http://localhost",
    "Check": {
      "DeregisterCriticalServiceAfter": "1m",
      "HttpHealth": "api/v1/health",
      "Interval": "10s"
    }
  }
}

In your appsettings.json, create a section with the above information, where:

• Name - Name of your service as it will be registered on Consul. Incidentally, this will also serve as the serviceId.
• Port - Port your service will be listening on.
• ConsulUrl - Full url (including port) to Consul.
• Address - Base url of your service.
• Check - Optional settings that control health checks on your service.
  • DeregisterCriticalServiceAfter - A value that specifies that checks associated with a service should deregister after this time.
  • HttpHealth - Url to the endpoint to be called for health checks while using the HTTP protocol on your service. MUST NOT include the base path of your service.
  • Interval - Frequency at which to run health check.

2. ASP.Net Core Web App

1. In the ConfigureServices method of your Startup.cs file, add below.

public void ConfigureServices(IServiceCollection services)
{
    // The library will require the HttpClientFactory to enable API calls to Consul.
    services.AddHttpClient();
    
    // Use IOptions Pattern to ensure settings entered in appsettings.json are available to us.
    services.Configure<ConsulRegistrationSettings>(Configuration.GetSection("ConsulSettings"));
    
    // Register a singleton to assist in querying Consul for information on registered services.
    services.AddSingleton<IConsulRegistryReader, ConsulRegistryReader>();
    
    // We take advantage of Hosted Services functionality to allow us to automatically register to Consul once our service is up.
    services.AddHostedService<ConsulRegistryWriter>();
}

2. Then in the Configure method

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
  loggerFactory.AddConsole(Configuration.GetSection("Logging"));
}

3. Console App

In your Program.cs file

internal class Program
{
    public static IServiceProvider ServiceProvider;
    private static void Main(string[] args)
    {
      // Set up dependancy injection
      ServiceProvider = new ServiceCollection()
        .AddLogging()
        .AddHttpClient()
        .Configure<ConsulRegistrationSettings>(configuration.GetSection("ConsulSettings"))
        .AddSingleton<IConsulRegistryReader, ConsulRegistryReader>()
        .AddSingleton<IConsulRegistryWriter, ConsulRegistryWriter>()
        .BuildServiceProvider();
        
        // Get instance of the registration writer.
        var registrar = ServiceProvider.GetService<IConsulRegistryWriter>();
        
        //Manually call the RegisterAsync method
        registrar.RegisterAsync().GetAwaiter().GetResult();
    }
}    

Usage

• Registering to Consul

  • Manually - by obtaining an instance of IConsulRegistryWriter we can call it's RegisterAsync method and if all settings are valid, then our service gets registered on Consul.
  • Automatically - by registering ConsulRegistryWriter as a HostedService (like in the web app example), the RegisterAsync gets run exactly once when the service is up and running.

• Querying Consul

  • We can obtain an instance of IConsulRegistryReader via dependancy injection, then call GetServiceBaseAddressAsync(string serviceId) to obtain the url of a service identified by serviceId.

  For richer information about a given service, then you can call the method GetServiceRawSettingsAsync(string serviceId)

Examples

Currently available example is a Console app. Find it in the 'Examples' directory.