Deploy a Rust API from your AI agent, over MCP

Prerequisites

• A Rust API, with its Cargo.toml.
• An AI agent that works in a terminal: Claude Code, Codex, Cursor or Gemini CLI.

Step 1: Give your agent these instructions

Open your agent in your API’s folder and paste these instructions into it:

Connect to while with my account (while.sh/agents), then deploy my app.

Without an account, your agent deploys your API as a trial, in one request. To keep it, open the link it gives you and create your account.

With your account, your agent adds while’s MCP server itself. If it asks you to, restart it. On the first call to while, a page opens in your browser. In Claude Code, if it doesn’t open, type /mcp, choose while, then Authenticate. On that page, choose your app, or “A new app”, then click Authorize.

Step 2: Open your API

Your agent gives you your API’s address, for example https://mon-api.while.cloud, over HTTPS.

What your agent does

It writes while.yaml at the root of your API:

apiVersion: while/v1
project: mon-api
services:
  - name: web
    port: 8080
    health:
      path: /health

while recognizes Rust by its Cargo.toml, and your agent gets a Dockerfile ready to build: cargo build --release, then your binary in a minimal Debian image, without admin rights. Your API listens on the port it receives in PORT, like this Axum API¹:

use axum::{routing::get, Router};

#[tokio::main]
async fn main() {
    let port = std::env::var("PORT").unwrap_or_else(|_| "8080".into());
    let app = Router::new()
        .route("/", get(|| async { "Bonjour" }))
        .route("/health", get(|| async { "ok" }));
    let listener = tokio::net::TcpListener::bind(format!("0.0.0.0:{port}")).await.unwrap();
    axum::serve(listener, app).await.unwrap();
}

Add a database

Your agent declares the database in while.yaml, and its address reaches your code in DATABASE_URL. It is backed up every day, and can go back to a precise moment if needed.

Speed things up with a cache

Your agent declares a Redis-compatible cache, connected to your code with its password.

Restrict your API to your colleagues

Your agent adds two lines to the service:

    access: internal
    email_domains: [acme.com]

Once your Google Workspace or Microsoft 365 is connected to while, on the Pro plan, your colleagues open the API with their usual account, and your code receives their name and email address, with no sign-in page to write.

Move to your own domain

Your agent declares the domain, you add the DNS records it gives you, and the HTTPS certificate follows.

Fix a vulnerability in your dependencies

Your API’s dependencies are checked against known vulnerabilities at every deployment, then every day. Your agent is notified of a serious vulnerability, and updates the package involved.

Go back to the previous version

In the 30 minutes after a deployment, the previous version comes back in a second. After that, it takes a few seconds. Once the previous version is back, your agent reads what broke in while’s logs, fixes it and deploys again.

In the docs: PostgreSQL databases, Valkey cache (Redis), Internal access, Custom domain, Versions and rollback and Dependency vulnerabilities.

Next steps

• Deploy a Go API
• Deploy a Docker container
• Add a Redis-compatible cache