Host a Rust Discord bot (serenity, poise)

Startup → Docker Image → Rust. There are two ways to run it.

Way 1: we build it

Upload Cargo.toml, Cargo.lock, the src folder and .env (not target). On start we run cargo build --release and start your program.

The first build takes a few minutes; later builds only redo what changed. Building a Discord library needs about 1 GB of memory or more. If the console says Killed, use way 2.

Way 2: build on your computer (best for small plans)

rustup target add x86_64-unknown-linux-musl
cargo build --release --target x86_64-unknown-linux-musl

Upload target/x86_64-unknown-linux-musl/release/<your bot> to the main folder, type its name in Main file, and turn off Install packages on start. Starts in a second, uses little memory.

The code

Cargo.toml:

[package]
name = "mybot"
version = "0.1.0"
edition = "2021"

[dependencies]
serenity = "0.12"
tokio = { version = "1", features = ["macros", "rt-multi-thread"] }
dotenvy = "0.15"

src/main.rs:

use serenity::async_trait;
use serenity::model::gateway::Ready;
use serenity::prelude::*;

struct Handler;

#[async_trait]
impl EventHandler for Handler {
    async fn ready(&self, _: Context, ready: Ready) {
        println!("Logged in as {}", ready.user.name);
    }
}

#[tokio::main]
async fn main() {
    dotenvy::dotenv().ok();
    let token = std::env::var("DISCORD_TOKEN").expect("DISCORD_TOKEN is missing");
    let mut client = Client::builder(&token, GatewayIntents::GUILDS)
        .event_handler(Handler)
        .await
        .expect("could not create the client");
    client.start().await.expect("the client stopped");
}

.env holds the token: DISCORD_TOKEN=your-token-here.

More help: Run your Discord bot 24/7.