DarkXaHTeP.CommandLine

Allows creating CommandLine applications using Microsoft.Extensions.CommandLineUtils together with DI, Configuration and Logging in a convenient way similar to AspNetCore Hosting.

NuGet

Build

Getting Started

To use the library you need to go through 2 simple steps:

Define Startup class similar to Asp.Net Core:

public class Startup
{   
    public void Configure(IApplicationBuilder app)
    {
        app.OnExecute(async () =>
        {
            Console.WriteLine("Hello World")
            return 0;
        });
    }
}

Create CommandLine Host using CommandLineHostBuilder and run it:

static class Program
{
    static int Main(string[] args)
    {
        ICommandLineHost host = new CommandLineHostBuilder()
            .UseStartup<Startup>()
            .Build();
            
        return host.Run(args);
    }
}

The application will print "Hello World" to console output and exit with 0 code.

Release notes

For release notes please see CHANGELOG.md

Startup class

Same as Asp.Net Core Startup, CommandLine Startup can have two methods:

void Configure(IApplicationBuilder app) is required. This is where application arguments and commands configuration happens using IApplicationBuilder.

void ConfigureServices(IServiceCollection services) is optional. Allows configuring Dependency Injection by providing access to application's IServiceCollection. This method is invoked prior to Configure

IApplicationBuilder interface

This interface provides a set of methods for configuring application. These methods are similar to provided by Microsoft.Extensions.CommandLineUtils (actually this library uses CommandLineUtils internally, however this may change in future due to the fact that CommandLineUtils is no longer supported).

IServiceProvider ApplicationServices { get; }

gives access to services registered in application

IApplicationBuilder Parent { get; }

contains link to parent IApplicationBuilder. Is null for the root builder

CommandArgument Argument(string name, string description, bool multipleValues = false);

allows to define command argument

IApplicationBuilder Command (string name, Action<IApplicationBuilder> configure, bool throwOnUnexpectedArg = true);

allows to define command

void OnExecute (Func<System.Threading.Tasks.Task<int>> invoke);
void OnExecute (Func<int> invoke);

allows to define root or command execution callback

CommandOption Option (string template, string description, CommandOptionType optionType);

allows to define option

void ShowHelp (string commandName = null);

shows help for the particular command or a whole app. Could be used in execute callbacks

Example:

var greeter = app.ApplicationServices.GetRequiredService<IGreeter>();
 
app.OnExecute(() => {
    app.ShowHelp();
    return 0;
});
 
app.Command("greet", command => {
    var casualOption = command.Option("-c|--casual", "This greeting is informal/casual", CommandOptionType.NoValue);
    var nameArgument = command.Argument("<name1 name2>", "Names of persons to greet separated with space", true);
    
    command.OnExecute(async () => {
        string names = nameArgument.Values;
        bool isCasual = casualOption.HasValue();
        
        string greeting = await greeter.GetGreetingAsync(isCasual);
        greeter.GreetAll(greeting, names);
        
        return 0;
    });
});

CommandLineHostBuilder class

This class is similar to WebHostBuilder from Asp.Net Core and allows to setup application configuration, logging and arguments parsing strategy before execution.

ICommandLineHostBuilder ConfigureAppConfiguration(Action<IConfigurationBuilder> configureDelegate);
ICommandLineHostBuilder ConfigureAppConfiguration(Action<CommandLineHostBuilderContext, IConfigurationBuilder> configureDelegate);

allows to configure application configuration

ICommandLineHostBuilder ConfigureLogging(Action<ILoggingBuilder> configureLogging);
ICommandLineHostBuilder ConfigureLogging(Action<CommandLineHostBuilderContext, ILoggingBuilder> configureLogging);

allows to configure logging

ICommandLineHostBuilder UseContentRoot(string contentRoot);

allows to redefine content root that will be used for resolving relative paths (e.g. path to json configuration file if used)

ICommandLineHostBuilder UseStartup<TStartup>() where TStartup : class;

sets Startup class to use. This method is required to call because no automatic Startup discovery is implemented

ICommandLineHostBuilder AllowUnexpectedArgs();

changes argument parsing to be less strict and not throw on unexpected arguments

ICommandLineHost Build();

builds command line host

ICommandLineHostBuilder ConfigureServices(Action<IServiceCollection> configureServices);
ICommandLineHostBuilder ConfigureServices(Action<CommandLineHostBuilderContext, IServiceCollection> configureServices);

allows to define additional services. Could be used in extension methods to extend behaviour

Example:

static class Program
{
    static int Main(string[] args)
    {
        ICommandLineHost host = new CommandLineHostBuilder()
            .UseContentRoot(Directory.GetCurrentDirectory())
            .ConfigureLogging(logging =>
            {
                logging
                    .AddConsole()
                    .AddDebug();
            })
            .ConfigureAppConfiguration(config =>
            {
                config
                    .AddJsonFile("appsettings.json")
                    .AddConsul("application")
                    .AddEnvironmentVariables();
            })
            .UseStartup<Startup>()
            .AllowUnexpectedArgs()
            .Build();

        return host.Run(args);
    }
}

Dependency Injection

It is possible to inject dependencies either through constructor of Startup class or Configure method, however only built-in dependencies (IConfiguration, ICommandLineEnvironment, ILogger<> etc.) are available through constructor because ConfigureServices method is not yet called.

Example:

public class Startup
{   
    public Startup(
        IConfiguration config,
        ICommandLineEnvironment environment,
        ILogger<Startup> logger
    )
    {}
    
    public void Configure(IApplicationBuilder app, IMyService service)
    {
    }
    
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<IMyService, MyService>();
    }
}

Acknowledgements

This library is highly inspired by AspNet.Core Hosting from Microsoft

Contribution

Feel free to ask questions and post bugs/ideas in the issues, as well as send pull requests.