Setting up a dev container for Rust

• Primary author: Reece Corter
• Reviewer: Benjamin Corter

Overview

This tutorial will help you: - Create a blank directory and initialize a new Git repository into it - Set up a Dev Container with the official Rust image and 'rust-analyzer' - Write a basic program that will print Hello COMP423 - Understand the difference between 'cargo build' and 'cargo run' and their uses

Prerequisites

• Visual Studio Code
• Docker Desktop
• Basic Git knowledge

No Rust install on Host

DO NOT install Rust locally. We will install & run everything in a dev container.

---

Step 1: Create a Blank Directory & Initialize Git Repo

mkdir rust-hello
cd rust-hello
git init

Step 2: Dev Container Configuration

1. Create a folder named .devcontainer and navigate into it:

mkdir .devcontainer
cd .devcontainer

1. Create a file named devcontainer.json with the following contents:

{
    "name": "Rust DevContainer",
    "image": "mcr.microsoft.com/devcontainers/rust:1",
    "customizations": {
      "vscode": {
        "settings": {},
        "extensions": ["rust-lang.rust-analyzer"]
      }
    }
  }

---

Step 3: Reopen in Dev Container

1. In Visual Studio Code, open the rust-hello folder.
2. Press Ctrl + Shift + P & select Dev Containers: Reopen in Container.
3. Wait for the container to build.

When completed, run:

rustc --version

You should see something like `rustc 1.x.x (yyyy-mm-dd)'. (1.84.0 as of 2025-01-09)

---

Step 4: Create a New Rust Project

From inside the Dev Container terminal:

cd /workspaces/rust-hello
cargo new --bin --vcs none hello-comp423

• '--bin' creates a binary (executable) project.
• '--vcs none prevents Cargo from creating another Git repo inside 'hello-comp423'.

---

Step 5: Write "Hello COMP423" Program

Open 'hello-comp423/src/main.rs'. Replace any existing code with:

fn main(){
    println!("Hello COMP423");
}

---

Step 6: Build & Run Program

Option A: Build & Run Manually

cd hello-comp423
cargo build
./target/debug/hello-comp423

This should output:

Hello COMP423

Relation to 'gcc' in COMP211

'cargo build' is similar to using 'gcc hello-comp423.c -o hello-comp423': it compiles the program but does not run automatically.

---

Option B: Build & Run in One Step

cargo run

This command compiles (if needed) and executes the program. You will see:

Compiling hello-comp423 v0.1.0
Running 'target/debug/hello-comp423'
Hello COMP423

Difference from 'cargo build'

• 'cargo build': only compiles your program.
• 'cargo run': compiles and immediately runs the compiled file in a single command.

---

Summary

• Step 1: Create a new folder, git init.
• Step 2: Add '.devcontainer/devcontainer.json' with the Rust base image + 'rust-analyzer'.
• Step 3: Reopen in container, verify 'rustc --version'.
• Step 4: Create project with cargo new --bin --vcs none hello-comp423.
• Step 5: Write "Hello COMP423" in main.rs.
• Step 6: Compile with cargo build and run the resulting file manually (Option A), or use cargo run (Option B) to do it all in one step.

---