C# / .NET

using Discord;
using Discord.WebSocket;

class Program
{
    private DiscordSocketClient _client = null!;

    public static Task Main(string[] args) => new Program().MainAsync();

    public async Task MainAsync()
    {
        var config = new DiscordSocketConfig
        {
            GatewayIntents = GatewayIntents.Guilds
                            | GatewayIntents.GuildMessages
                            | GatewayIntents.MessageContent,
            // Repoint REST + Gateway at Astral
            RestClientProvider = Discord.Net.Rest.DefaultRestClientProvider.Create(useProxy: false),
            // The cleanest path: subclass DefaultRestClient or set
            // DiscordConfig.APIUrl + DiscordRestConfig before constructing
            // the client.
        };

        // Discord.Net allows overriding the API base by reflection on
        // DiscordConfig.APIUrl, or by using DiscordSocketConfig with a
        // custom rest provider that prefixes the Astral host.
        typeof(DiscordConfig)
            .GetField("APIUrl", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Static)!
            .SetValue(null, "https://astraof.com/api/v1/");

        _client = new DiscordSocketClient(config);
        _client.Log += msg => { System.Console.WriteLine(msg); return Task.CompletedTask; };
        _client.MessageReceived += HandleMessage;

        await _client.LoginAsync(TokenType.Bot, System.Environment.GetEnvironmentVariable("ASTRAL_BOT_TOKEN"));
        await _client.StartAsync();
        await Task.Delay(-1);
    }

    private async Task HandleMessage(SocketMessage msg)
    {
        if (msg.Author.IsBot) return;
        if (msg.Content == "!ping")
        {
            await msg.Channel.SendMessageAsync("pong");
        }
    }
}