🧠 Code Execution Service

A lightweight, secure, and efficient code execution engine designed to run user-submitted code inside isolated Docker containers. Perfect for online judges, code battles, and learning platforms.

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📐 Architecture Overview

                   ┌────────────────────────┐
                   │      Frontend UI       │
                   │  (Code Battle App)     │
                   └──────────┬─────────────┘
                              │
                              ▼
                   ┌────────────────────────┐
                   │   Backend API Server   │
                   │  (Handles Submission)  │
                   └──────────┬─────────────┘
                              │ Push JSON job
                              ▼
                     ┌────────────────┐
                     │  Redis Queue   │ ◄────── Push job to `submit`
                     └────────────────┘
                              │
                              ▼
       ┌──────────────────────────────────────────┐
       │    Code Execution Service (Worker)       │
       │  ▸ Reads from Redis `submit` queue        │
       │  ▸ Extracts code, input, language, etc.   │
       │  ▸ Creates files inside /submissions      │
       │  ▸ Calls Docker container to execute code │
       │  ▸ Compares output with test cases        │
       │  ▸ Pushes result to `result` queue        │
       └──────────────────────────────────────────┘
                              │
                              ▼
                     ┌────────────────┐
                     │  Redis Queue   │
                     │   `result`     │
                     └────────────────┘
                              │
                              ▼
                   ┌────────────────────────┐
                   │     Leaderboard /      │
                   │     Result Display     │
                   └────────────────────────┘

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📂 Folder Structure

code-execution-service/
├── node_modules/
├── outputs/                  # Execution outputs
├── submissions/              # Code submission files
├── index.js                  # Main entry point (worker)
├── package.json              # Node.js dependencies
├── Container-logic/
│   └── App/
│       ├── engine            # Execution logic (inside Docker)
│       └── dockerfile        # Docker image setup

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🚀 How to Run Locally

1. Clone the Repository

git clone https://github.com/yourusername/code-execution-service.git
cd code-execution-service

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2. Pull Docker Image

Make sure Docker is installed and running, then pull the prebuilt image:

docker pull ayushgupta712005/judge-runner:latest

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3. Open Project in VS Code

code .

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4. Start Docker Container

From inside the code-execution-service directory, run the container:

docker run -d --name judge-python \
  -v ${PWD}/submissions:/app/submissions \
  -v ${PWD}/outputs:/app/outputs \
  ayushgupta712005/judge-runner:latest

✅ This:

• Mounts submissions and outputs to the container
• Runs the image in background mode

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5. Start Redis Server

You can either start Redis locally or use Docker:

docker run -d --name redis -p 6379:6379 redis

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6. Push a Job to the Redis submit Queue

You can push this JSON payload using redis-cli or a GUI like RedisInsight:

{
  "language": "java",
  "input": "import java.util.*;\npublic class Main\n{   \n\tpublic static void main(String[] args) {\n\t\tScanner s=new Scanner(System.in);\n\t\tString str=s.nextLine();\n\t\tSystem.out.println(isValid(str));\n\t}\n\t public static boolean isValid(String s) {\n        int i = -1;\n        char[] stack = new char[s.length()];\n        for (char ch : s.toCharArray()) {\n            if (ch == '(' || ch == '{' || ch == '[')\n                stack[++i] = ch;\n            else {\n                if (i >= 0\n                    && ((stack[i] == '(' && ch == ')')\n                        || (stack[i] == '{' && ch == '}')\n                        || (stack[i] == '[' && ch == ']')))\n                    i--;\n                else\n                    return false;\n            }\n        }\n        return i == -1;\n    }\n}",
  "TestCase": [
    { "input": "()", "output": "true", "isHidden": false },
    { "input": "()[]{}", "output": "true", "isHidden": false },
    { "input": "(]", "output": "false", "isHidden": true }
  ],
  "id": "2134516",
  "timeLimit": 500
}

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7. Start the Execution Engine

From the root directory (code-execution-service), run:

node index.js

This script:

• Reads from the Redis submit queue
• Executes code using the Docker container
• Compares output with test cases
• Pushes result to a result queue

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🧪 Sample Output (Pushed to result Queue)

{
  "id": "2134516",
  "status": "Passed",
  "passedTestCases": 2,
  "totalTestCases": 3,
  "timeTaken": "420ms"
}

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📦 Docker Image

👉 ayushgupta712005/judge-runner

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🙌 Contribution

Open to feature improvements (e.g., multi-language support, better test case diffing, etc.) via PRs or suggestions!

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