Rust Development in Termux

In my holiday I used to Termux to do server maintenance in emergency cases and it worked pretty well. I thought about learning Rust and how this can be combined. Can I use my phone as a desktop development environment? In this post I am going to answer this question.

Desktop mode

I’ve got a Fairphone 3 with /e/OS/. The phone is outdated and does not support desktop mode: https://en.everybodywiki.com/List_of_devices_with_video_output_over_USB-C

However, I have a Bluetooth keyboard from Keychron https://www.keychron.com/. By switching to Bluetooth mode and holding fn+1 I was able to connect the keyboard with my phone.

When working with the phone like this, the auto lock and sleep mode of the phone can be annoying. I recommend to disable it.

Setup

Open the Termux app on your Android phone. You should find yourself in a bash shell.

We are going to install several tools, lets start with git.

pkg install git

Then we need a terminal multiplexer. I recommend tmux.

pkg install tmux

You can start tmux right away with tmux.

As we are going to implement rust, I think it would be nice to use a Rust based editor.

pkg install helix

Next up are the Rust build tools.

pkg install rust

Press y and wait for some time.

Check the rust compiler version with rustc -version.

Simple program

We are ready to code our first Rust program.

Start helix with hx. Then enter insert mode with i.

Write the following program:

fn main() {
	println!("Hello Mom!")
}

Switch to normal mode esc. Then save the file with : and w hello.rs

Then split the window with tmux ctrl+b and %. In the new window run the rust program.

rustc hello.rs

This will produce a binary hello that can be run with ./hello. You should see the output of the print statement.

To switch the tmux pane use ctrl+b and an arrow key.

Webserver

That was easy. Let’s implement something more interesting - a web server.

Bootstrap the project with cargo:

cargo new http-server
cd http-server

Close helix with :q! and open the project manifest with hx Cargo.yml.

Add the following block to the dependency section:

tide = "0.16.0"
async-std = { version = "1.8.0", features = ["attributes"] }
serde = { version = "1.0", features = ["derive"] }

Use :w to save the file.

Next edit the Rust program in helix with :o src/main.rs.

Delete everything with d and write this program.

#[async_std::main]
async fn main() -> Result<(), std::io::Error> {
    let mut app = tide::new();
    app.with(tide::log::LogMiddleware::new());

    app.at("/").get(|_| async { Ok("Hello Mom!") });
    app.listen("127.0.0.1:8080").await?;
    Ok(())
}

You can also copy the code above by opening this post in the browser of your phone. You can switch between Android apps with home+tab. To paste the code you most likely need to use the touch screen menu.

Now it is time to start the web server.

cargo run

Cargo will pull and build the required dependencies and then run the server.

Open a new tmux tab with ctrl+b and c. Then run this curl command:

curl http://localhost:8080

If you get “Hello Mom!” you did a great job!

Workflow improvements

Of course the current setup needs a lot of improvements. Here are some ideas that you can further discover.

• Auto save file in helix
• Automatically save tmux session state
• File navigation in Helix
• Expose web server with ssh tunnel
• Version control the code with git