Code Execution Engine

A secure, containerized code execution service that runs user code in isolated Docker containers and returns JSON results via HTTP callbacks.

Features

Multi-language support: Python, JavaScript, Java, C++, Go
Docker isolation: Each execution runs in isolated containers with resource limits
Async processing: Uses Celery for queuing and background execution
HTTP callbacks: Results delivered to your specified callback URL
Test-driven: Execute functions with multiple test cases and get detailed results
Security: No network access for executing code, input validation, timeouts

Architecture

HTTP Request → FastAPI → Celery Queue → Docker Container → Callback

Setup

Install dependencies:

pip install -r requirements.txt

Set environment variables:

export CELERY_BROKER_URL="redis://localhost:6379/0"
export CELERY_RESULT_BACKEND="redis://localhost:6379/0"

Start the services:

# Terminal 1: Start FastAPI server
python run_server.py

# Terminal 2: Start Celery worker
python celery_worker.py

# Terminal 3: Start callback receiver (for testing)
python callback_receiver.py

Run Like

JavaScript Example

Request:

curl -X POST "http://localhost:8000/execute" \
  -H "Content-Type: application/json" \
  -d '{
    "language": "js",
    "code": "function findMedianSortedArrays(nums1, nums2) {\n  if (nums1.length > nums2.length) {\n    return findMedianSortedArrays(nums2, nums1);\n  }\n  const m = nums1.length;\n  const n = nums2.length;\n  let low = 0, high = m;\n  while (low <= high) {\n    const cut1 = Math.floor((low + high) / 2);\n    const cut2 = Math.floor((m + n + 1) / 2) - cut1;\n    const left1 = cut1 === 0 ? -Infinity : nums1[cut1 - 1];\n    const left2 = cut2 === 0 ? -Infinity : nums2[cut2 - 1];\n    const right1 = cut1 === m ? Infinity : nums1[cut1];\n    const right2 = cut2 === n ? Infinity : nums2[cut2];\n    if (left1 <= right2 && left2 <= right1) {\n      if ((m + n) % 2 === 0) {\n        return (Math.max(left1, left2) + Math.min(right1, right2)) / 2.0;\n      } else {\n        return Math.max(left1, left2);\n      }\n    } else if (left1 > right2) {\n      high = cut1 - 1;\n    } else {\n      low = cut1 + 1;\n    }\n  }\n  return 1.0;\n}",
    "function_name": "findMedianSortedArrays",
    "imports": [],
    "test_cases": [
      {
        "input": [[1, 3], [2]],
        "expected_output": "2"
      },
      {
        "input": [[1, 2], [3, 4]],
        "expected_output": "2.5"
      },
      {
        "input": [[0, 0], [0, 0]],
        "expected_output": "0"
      },
      {
        "input": [[1, 3], [2, 7]],
        "expected_output": "2.5"
      }
    ],
    "callback_url": "http://localhost:5001/callback"
  }'

Response:

{
  "message": "Code execution task accepted",
  "id": "eb7411b2-b200-442f-97f5-c9164b31c974"
}

Callback Payload:

{
  "id": "eb7411b2-b200-442f-97f5-c9164b31c974",
  "results": [
    {
      "input": [[1, 3], [2]],
      "expected_output": "2",
      "actual_output": "2",
      "passed": true,
      "time": "0.0457 ms",
      "memory": "N/A"
    },
    {
      "input": [[1, 2], [3, 4]],
      "expected_output": "2.5",
      "actual_output": "2.5",
      "passed": true,
      "time": "0.0021 ms",
      "memory": "N/A"
    },
    {
      "input": [[0, 0], [0, 0]],
      "expected_output": "0",
      "actual_output": "0",
      "passed": true,
      "time": "0.0011 ms",
      "memory": "N/A"
    },
    {
      "input": [[1, 3], [2, 7]],
      "expected_output": "2.5",
      "actual_output": "2.5",
      "passed": true,
      "time": "0.0009 ms",
      "memory": "N/A"
    }
  ],
  "all_passed": true,
  "error": null,
  "error_details": null
}

Python Example

Request:

curl -X POST "http://localhost:8000/execute" \
  -H "Content-Type: application/json" \
  -d '{
    "language": "python",
    "code": "def add_numbers(a, b):\n    return a + b",
    "function_name": "add_numbers",
    "imports": [],
    "test_cases": [
      {
        "input": [2, 3],
        "expected_output": "5"
      },
      {
        "input": [10, -5],
        "expected_output": "5"
      }
    ],
    "callback_url": "http://localhost:5001/callback"
  }'

Callback Payload:

{
  "id": "12345678-1234-1234-1234-123456789012",
  "results": [
    {
      "input": [2, 3],
      "expected_output": "5",
      "actual_output": "5",
      "passed": true,
      "time": "0.0123 ms",
      "memory": "N/A"
    },
    {
      "input": [10, -5],
      "expected_output": "5",
      "actual_output": "5",
      "passed": true,
      "time": "0.0098 ms",
      "memory": "N/A"
    }
  ],
  "all_passed": true,
  "error": null,
  "error_details": null
}

Java Example

Request:

curl -X POST "http://localhost:8000/execute" \
  -H "Content-Type: application/json" \
  -d '{
    "language": "java",
    "code": "class Solution {\n    public int addNumbers(int a, int b) {\n        return a + b;\n    }\n}",
    "function_name": "addNumbers",
    "imports": [],
    "test_cases": [
      {
        "input": [5, 7],
        "expected_output": "12"
      }
    ],
    "callback_url": "http://localhost:5001/callback"
  }'

Error Example

Request with syntax error:

curl -X POST "http://localhost:8000/execute" \
  -H "Content-Type: application/json" \
  -d '{
    "language": "python",
    "code": "def broken_function(x):\n    return x +",
    "function_name": "broken_function",
    "imports": [],
    "test_cases": [
      {
        "input": [5],
        "expected_output": "5"
      }
    ],
    "callback_url": "http://localhost:5001/callback"
  }'

Callback Payload:

{
  "id": "error-example-id",
  "results": [
    {
      "input": [5],
      "expected_output": "5",
      "actual_output": "Execution Failed",
      "passed": false,
      "time": "0.0 ms",
      "memory": "N/A"
    }
  ],
  "all_passed": false,
  "error": "Execution environment error",
  "error_details": "Execution failed with exit code 1.\n  File \"/usr/src/app/temp_script.py\", line 2\n    return x +\n             ^\nSyntaxError: invalid syntax"
}

API Reference

POST /execute

Submits code for execution.

Request Body:

language (string): One of "python", "js", "java", "cpp", "go"
code (string): The source code containing the function to test
function_name (string): Name of the function to call
imports (array): List of imports/modules to include (language-specific)
test_cases (array): List of test cases with input and expected_output
callback_url (string): URL where results will be POSTed

Response:

message (string): Confirmation message
id (string): Unique execution ID for tracking

Resource Limits

Memory: 256MB for Python/JS, 512MB for Java/C++/Go
CPU: 1 core maximum
Time: 15-30 seconds depending on language
Network: Disabled during execution

Supported Languages

Language	Container	Features
Python	python:3.10	Standard library, JSON
JavaScript	node:18	ES6+, performance timing
Java	openjdk:11	Reflection, Gson, generics
C++	gcc:latest	C++17, STL, chrono
Go	golang:1.21	Standard library, JSON

Docker Requirements

Make sure Docker is installed and running. The service will automatically pull required images on first use.

Environment Variables

CELERY_BROKER_URL: Redis URL for Celery message broker
CELERY_RESULT_BACKEND: Redis URL for Celery result storage
HOST: FastAPI server host (default: 127.0.0.1)
PORT: FastAPI server port (default: 8000)

siinghd/simple-code-execution-engine

README

Code Execution Engine

Features

Architecture

Setup

Run Like

JavaScript Example

Python Example

Java Example

Error Example

API Reference

POST /execute

Resource Limits

Supported Languages

Docker Requirements

Environment Variables

Contributors

Issues