Add Alternative Free C++ Code Execution Service

[TryOmar]

Issue: Replace Judge0 C++ Runner (Quota Almost Finished)

Summary

We're using Judge0 (RapidAPI) to run C++ code, but we've reached 85% of the free quota. We need a new free or self-hosted solution to avoid overage fees.

What We Need

• A reliable service to run C++ code.
• Support for basic input (cin) if possible.
• Works smoothly with our current client flow.

Goal

Keep C++ code execution working without extra costs.

[TryOmar]

We've run out of quota

[Abbas49]

🚀 How to Host Judge0 Extra CE v1.13.1 Locally on Ubuntu

This guide explains everything you need to deploy Judge0 Extra CE v1.13.1 on an Ubuntu server using a single automated installation script.

Judge0 is a powerful open-source code execution API used for online judges, coding platforms, and automated code testing.

---

📌 1. Server Requirements

Make sure your Ubuntu machine meets the following minimum specifications:

Resource	Minimum
vCPU	2 cores
RAM	4 GB
Storage	20 GB
Operating System	Ubuntu 20.04 or newer
Open Port	2358

Port 2358 must be open on your firewall / cloud provider
Example:

• UFW: sudo ufw allow 2358
• AWS Security Group: Add inbound rule for TCP/2358
• DigitalOcean Firewall: Allow TCP 2358
• Azure NSG: Add rule for TCP 2358

---

📁 2. What This Script Does

The script below will:

✔ Install required packages
✔ Download Judge0 Extra CE
✔ Generate secure passwords
✔ Install Docker + official Docker Compose plugin
✔ Run all Judge0 services in Docker
✔ Start the Judge0 API and database containers
✔ Show you where to access your installation

This is fully automated — just copy, paste, and run.

---

▶️ 3. Run the Installer Script

Copy and run the following script on your Ubuntu server:

#!/bin/bash
set -e

echo "==========================================="
echo "     🚀 Starting Judge0 Installation"
echo "==========================================="

# -------------------------------
# 1. System Update
# -------------------------------
echo "[1/8] 🔄 Updating system packages..."
sudo apt update -y


# -------------------------------
# 2. Download Judge0
# -------------------------------
echo "[2/8] ⬇ Downloading Judge0..."
wget -q https://github.com/judge0/judge0/releases/download/v1.13.1-extra/judge0-v1.13.1-extra.zip

echo "[2/8] 📦 Installing unzip, curl, ca-certificates, openssl..."
sudo apt install -y unzip curl ca-certificates openssl

echo "[2/8] 📂 Unpacking Judge0..."
unzip -q judge0-v1.13.1-extra.zip

cd judge0-v1.13.1-extra


# -------------------------------
# 3. Generate Passwords
# -------------------------------
echo "[3/8] 🔐 Generating secure passwords for Redis and PostgreSQL..."

REDIS_PASSWORD=$(openssl rand -base64 16)
POSTGRES_PASSWORD=$(openssl rand -base64 16)

echo " → Generated Redis Password: $REDIS_PASSWORD"
echo " → Generated PostgreSQL Password: $POSTGRES_PASSWORD"

CONFIG_FILE="judge0.conf"

echo "[3/8] ✏ Updating configuration file ($CONFIG_FILE)..."
sed -i "s/^REDIS_PASSWORD=.*/REDIS_PASSWORD=\"$REDIS_PASSWORD\"/" "$CONFIG_FILE"
sed -i "s/^POSTGRES_PASSWORD=.*/POSTGRES_PASSWORD=\"$POSTGRES_PASSWORD\"/" "$CONFIG_FILE"

echo " → Configuration updated successfully."


# -------------------------------
# 4. Remove Old Docker
# -------------------------------
echo "[4/8] 🗑 Removing any old Docker installations (if present)..."
sudo apt remove -y $(dpkg --get-selections | awk '$1 ~ /docker|containerd|runc/ {print $1}') || true
echo " → Old Docker removed (if existed)."


# -------------------------------
# 5. Install Docker (Official)
# -------------------------------
echo "[5/8] 🐳 Installing Docker Engine + Official Compose Plugin..."

echo " → Adding Docker GPG key..."
sudo install -m 0755 -d /etc/apt/keyrings
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
sudo chmod a+r /etc/apt/keyrings/docker.asc

echo " → Adding Docker repository..."
source /etc/os-release
sudo tee /etc/apt/sources.list.d/docker.sources >/dev/null <<EOF
Types: deb
URIs: https://download.docker.com/linux/ubuntu
Suites: ${UBUNTU_CODENAME:-$VERSION_CODENAME}
Components: stable
Signed-By: /etc/apt/keyrings/docker.asc
EOF

echo " → Updating apt index..."
sudo apt update -y

echo " → Installing Docker CE and OFFICIAL Docker Compose plugin..."
sudo apt install -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

echo " → Docker installation complete (official only, no legacy compose)."


# -------------------------------
# 6. Start Judge0 Database Services
# -------------------------------
echo "[6/8] 🛢 Starting database containers (db, redis)..."
sudo docker compose up -d db redis

echo " → Waiting 10 seconds for DB initialization..."
sleep 10


# -------------------------------
# 7. Start Judge0 Services
# -------------------------------
echo "[7/8] 🚀 Starting main Judge0 services..."
sudo docker compose up -d

echo " → Waiting 5 seconds..."
sleep 5


# -------------------------------
# 8. Final Message
# -------------------------------
echo "==========================================="
echo " 🎉 Judge0 installation completed!"
echo "==========================================="
echo "Your instance of Judge0 Extra CE v1.13.1 is now up and running."
echo "Visit documentation at:"
echo "  👉  http://<IP ADDRESS OF YOUR SERVER>:2358/docs"
echo "==========================================="