Program.cs

using AspNetCoreExample;
using SlackNet.AspNetCore;
using SlackNet.Events;

var builder = WebApplication.CreateBuilder(args);

var slackSettings = builder.Configuration.GetSection("Slack").Get<SlackSettings>()!;

builder.Services.AddSlackNet(c => c
    // Configure the tokens used to authenticate with Slack
    .UseApiToken(slackSettings.ApiToken) // This gets used by the API client
    .UseAppLevelToken(slackSettings.AppLevelToken) // (Optional) used for socket mode
    
    // The signing secret ensures that SlackNet only handles requests from Slack 
    .UseSigningSecret(slackSettings.SigningSecret)
    
    // Register your Slack handlers here
    .RegisterEventHandler<MessageEvent, PingDemo>()
);

var app = builder.Build();

// This sets up the SlackNet endpoints for handling requests from Slack
// By default the endpoints are /slack/event, /slack/action, /slack/options, and /slack/command,
// but the 'slack' prefix can be changed using MapToPrefix.
app.UseSlackNet(c => c
    // You can enable socket mode for testing without having to make your web app publicly accessible
    .UseSocketMode(false)
);

app.MapGet("/", () => "Hello, Slack!");

app.Run();

record SlackSettings
{
    public string ApiToken { get; init; } = string.Empty;
    public string AppLevelToken { get; init; } = string.Empty;
    public string SigningSecret { get; init; } = string.Empty;
}