Setting Up a Dev Container for Go

Primary author: Sanjana Gopalswamy
Reviewer: Caitlin Estrada

Prerequisites

Before getting started, ensure you have the following installed on your system:

Visual Studio Code – A lightweight code editor that supports DevContainers.
Docker – Required to run the DevContainer.
VS Code Extensions:
- Dev Containers (install from VS Code marketplace)
- Go (Made by the Go Team at Google)

Step 1: Create a New Project Directory

Open the terminal and create a new directory for your project:
```
mkdir comp423-go-tutorial
cd comp423-go-tutorial
```
Initialize a new Git repository:
```
git init
```

Step 2: Add Development Container Configuration

Open the comp423-go-tutorial directory in VS Code:
- Go to File > Open Folder and select your project directory.
Install the Dev Containers extension:
- Open the Extensions Marketplace (Ctrl+Shift+X), search for "Dev Containers," and install it.
Create a .devcontainer directory in the project root:
```
mkdir .devcontainer
```

Tip:

You can also create a new file through VSCode's Explorer panel.

Inside the .devcontainer directory, create a devcontainer.json file with the following content:

{
  "name": "COMP423 Go Tutorial",
  "image": "mcr.microsoft.com/devcontainers/go:latest",
  "customizations": {
    "vscode": {
      "extensions": ["golang.go"]
    }
  },
  "postCreateCommand": "go mod init comp423-go-tutorial"
}

Explanation of `devcontainer.json`:

name: Specifies a descriptive name for the DevContainer.
image: Uses Microsoft's official Go DevContainer image.
customizations: Installs the official Go extension for VS Code.
postCreateCommand: Initializes a Go module for dependency management.

Step 3: Reopen in Dev Container

Open the command palette in VS Code (Cmd+Shift+P) and run: Dev Containers: Reopen in Container
Wait for the container to build and start.

Step 4: Verify Go Installation

Open a terminal inside the container and run:
```
go --version
```

Look Out

Make sure it outputs a recent Go version! (i.e. Such as go version ex. Go 1.23)

Step 5: Create a Hello COMP423 Program

Create a new file main.go in the project root with the following content:

package main

import "fmt"

func main() {
    fmt.Println("Hello COMP423")
}

Initialize the Go module:
```
go mod tidy
```

Step 6: Running and Building the Go Program

Run the Go program directly:
```
go run main.go
```

Did you know?

This command compiles and runs the program in a single step!

Build the Go program:

go build -o hello_comp423 main.go

This generates an executable binary named hello_comp423.

./hello_comp423

3. Unlike go run, the compiled binary does not need the Go environment to execute.

Explanation of Commands

go run: Compiles and runs the program temporarily without generating an executable file.
go build: Compiles the source code and produces a standalone binary, similar to using gcc for C programs.

Running the binary: Executes the compiled program without involving the Go runtime directly.

Success!

You have successfully set up a DevContainer for Go, written a "Hello COMP423" program, and learned how to run and build it. You can now continue developing Go applications within a consistent and containerized environment.

Citations & Resources

Go Documentation

COMP423 MkDocs Tutorial