Proceed with the official Rust documentation on a Docker container (2. Program a number guessing game)

Introduction

As the title says. Last time: Proceed with Rust official document on Docker container (1. Getting started)

Referenced

Rust Official Document (The Rust Programming Language Japanese Version): https://doc.rust-jp.rs/book-ja/title-page.html DokerHub(Rust)：https://hub.docker.com/_/rust

2. Program the number guessing game

Official document: https://doc.rust-jp.rs/book-ja/ch02-00-guessing-game-tutorial.html

First of all, check the whole thing. Since it seems that the following files need to be modified, we will take the method of copying the locally created one.

• src/main.rc
• Cargo.toml

Create main.rc and Cargo.toml to copy to the container. In addition, the folder structure of what is created locally.

guessing_game
 - src/main.rc
 - Cargo.toml

guessing_game/src/main.rc

extern crate rand;

use std::io;
use std::cmp::Ordering;
use rand::Rng;

fn main() {
    println!("Guess the number!");

    let secret_number = rand::thread_rng().gen_range(1, 101);

    loop {
        println!("Please input your guess.");

        let mut guess = String::new();

        io::stdin().read_line(&mut guess)
            .expect("Failed to read line");

        let guess: u32 = match guess.trim().parse() {
            Ok(num) => num,
            Err(_) => continue,
        };

        println!("You guessed: {}", guess);

        match guess.cmp(&secret_number) {
            Ordering::Less => println!("Too small!"),
            Ordering::Greater => println!("Too big!"),
            Ordering::Equal => {
                println!("You win!");
                break;
            }
        }
    }
}

guessing_game/Cargo.toml

[package]
name = "guessing_game"
version = "0.1.0"
authors = ["root"]
edition = "2018"

[dependencies]
rand = "0.3.14"

Create a Dockerfile. Some are matched to the sample on Docker Hub. I'm using cargo init because I can't use cargo new in an existing directory.

Dockerfile

FROM rust:latest
WORKDIR /usr/src/projects
COPY . .

# 2.Programming a number guessing game
RUN cargo init guessing_game --bin && \
    cd /usr/src/projects/guessing_game && \
    cargo build
WORKDIR /usr/src/projects/guessing_game
CMD ["cargo", "run"]

When I built it, I got a cargo error

$ docker build -t my-rust-app .
(Omitted)
 ---> Running in 13aa45df5d36
error: `cargo init` cannot be run on existing Cargo packages
The command '/bin/sh -c cargo init guessing_game --bin &&     cd /usr/src/projects/guessing_game &&     cargo build' returned a non-zero code: 101

Apparently cargo init can use existing directories and sources, but Cargo.toml doesn't seem to work. Be quiet, carry new, and then overwrite with COPY.

Modified Dockerfile

FROM rust:latest
WORKDIR /usr/src/projects

# 2.Programming a number guessing game
RUN cargo new guessing_game --bin
COPY . .
RUN cd /usr/src/projects/guessing_game && \
    cargo build
WORKDIR /usr/src/projects/guessing_game
CMD ["cargo", "run"]

Build and confirm that the program works without problems

$ docker build -t my-rust-app .
$ docker run -it --rm --name my-running-app my-rust-app
    Finished dev [unoptimized + debuginfo] target(s) in 0.02s
     Running `target/debug/guessing_game`
Guess the number!
Please input your guess.
0
You guessed: 0
Too small!
Please input your guess.
100
You guessed: 100
Too big!
Please input your guess.
97
You guessed: 97
You win!

in conclusion

If you just want to create a learning environment for Rust, you can use mount.