Building a Go Playground REPL from Scratch with Docker, AWS & Vue.js

In this post, I’ll walk you through how I built a Go Playground REPL clone from scratch — powered by a Go backend that compiles user-submitted code securely in Docker, deployed with GitHub Actions to AWS Elastic Beanstalk, and paired with a beautiful frontend using Vue.js, Pinia, Tailwind CSS, and Monaco Editor.

Tech Stack

• Backend: Go (Golang), Docker, Gin, os/exec
• Frontend: Vue 3, Pinia, Tailwind CSS, Monaco Editor
• DevOps: GitHub Actions, DockerHub, AWS Elastic Beanstalk

What I Built

• An interactive code editor for writing and executing Go programs.
• A secure backend that:
• Runs code inside a Docker container
• Enforces timeouts to prevent infinite loops
• Handles malicious input gracefully
• A responsive frontend with live theme switching, program examples, and output panels.

Backend Setup

I used the os/exec package in Go to compile and run user code inside a Docker container, isolated from the host.

Sample Go run handler:

func RunCode(c *gin.Context) { var payload struct { Code string `json:"code"` } if err := c.ShouldBindJSON(&payload); err != nil { c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid request format"}) return } output, err := runInDocker(payload.Code) if err != nil { c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()}) return } c.JSON(http.StatusOK, gin.H{"output": output, "error": ""}) } 

Sample Dockerfile:

FROM golang:1.24-alpine WORKDIR /app COPY . . RUN go build -o repl-server ./cmd CMD [ "./repl-server" ] 

GitHub Actions Deployment

I set up GitHub Actions to automatically build our Docker image, push to ECR, and deploy to AWS Elastic Beanstalk.

Key CI/CD steps:

- name: Build Docker Image run: docker build -t repl-api . - name: Push to ECR run: | aws ecr get-login-password --region us-west-2 | docker login --username AWS --password-stdin ${{ secrets.ECR_URL }} docker tag repl-api:latest ${{ secrets.ECR_URL }}/repl-api:latest docker push ${{ secrets.ECR_URL }}/repl-api:latest - name: Deploy to EBS run: | eb init -p docker go-repl --region us-west-2 eb deploy 

Frontend Setup

Used Vue 3 with Pinia to manage state and Monaco Editor for code editing.

Vue + Monaco Editor integration (sample):

<template> <MonacoEditor v-model="code" :theme="isDark ? 'vs-dark' : 'vs-light'" language="go" /> </template> <script setup> import MonacoEditor from '@monaco-editor/vue' const code = ref(`package main\n\nimport "fmt"\n\nfunc main() {\n fmt.Println("Hello, world!")\n}`) </script> 

Sample UI with Tailwind CSS:

<div class="max-w-4xl mx-auto px-4 py-10"> <h1 class="text-3xl font-bold">Go Playground REPL</h1> <div class="h-96 mt-4 border rounded bg-white"> <CodeEditor v-model="code" /> </div> </div> 

Program Examples Dropdown

Added dropdown support with built-in Go examples like

• Fibonacci
• Peano Integers
• Prime Checker
• Bubble Sort
• Pi Calculation

Securing Execution

Used these techniques to sandbox the code:

• Timeout using context.WithTimeout
• Docker resource constraints (--memory, --cpus)
• Output/error size limits
• Validated JSON input structure

Future Improvements

This setup is built with extensibility in mind.

• Add support for JavaScript, Java, Python, etc.
• Enable stdin support in Docker for user input
• Add user accounts and save session history
• Use WebSocket for real-time compile streams

🌐 Live Demo

Go Playground

📝 Final Thoughts

This project was a fun blend of backend performance, frontend UX, and DevOps automation. It’s a perfect playground for experimenting with Go and building a polished, full-stack developer tool.

Feel free to fork and extend it further. Hope this helps you in your learning journey!

Repo
Github Repo