Judge0 Installation Full steps

 

Judge0 Installation & Running Document

Domain: judge.tr**klms.org
Server: AWS EC2 Ubuntu
Purpose: Deploy Judge0 code execution server with SSL using Nginx reverse proxy.

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1. Server Requirements

Minimum recommended server:

Ubuntu 22.04 LTS
2 vCPU
4 GB RAM minimum
40 GB SSD minimum

Recommended for live usage:

Ubuntu 22.04 LTS
2 vCPU or more
8 GB RAM
80 GB SSD

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2. Required Ports in AWS Security Group

Open these ports in EC2 Security Group:

22    SSH      Your IP only
80    HTTP     0.0.0.0/0
443   HTTPS    0.0.0.0/0

Do not expose Judge0 port 2358 publicly.

Judge0 will run internally on:

http://127.0.0.1:2358

Public users will access:

https://judge.tr**klms.org

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3. DNS Setup

In the domain DNS panel, create an A record:

Type: A
Name: judge
Value: EC2_PUBLIC_IP
TTL: Auto

Example:

judge.tr**klms.org  ->  Your EC2 public IP

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4. Update Server Packages

Run:

sudo apt update
sudo apt upgrade -y

Install basic required packages:

sudo apt install -y unzip curl wget nginx certbot python3-certbot-nginx

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5. Install Docker

Run:

sudo apt install -y docker.io

Enable and start Docker:

sudo systemctl enable docker
sudo systemctl start docker

Check Docker:

docker --version

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6. Install Docker Compose

First try:

sudo apt install -y docker-compose

Check:

docker-compose --version

If docker-compose is still not found, install manually:

sudo curl -L "https://github.com/docker/compose/releases/download/v2.27.1/docker-compose-linux-x86_64" -o /usr/local/bin/docker-compose

sudo chmod +x /usr/local/bin/docker-compose

Check again:

docker-compose --version

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7. Important Note About Judge0 Package

Do not use this package for our setup:

judge0-v1.13.0-https.zip

Because it starts its own Docker Nginx container and tries to use port 80.

We are using system Nginx and Certbot SSL, so use normal package:

judge0-v1.13.0.zip

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8. Stop Wrong HTTPS Package If Already Running

If HTTPS package was already started, stop it:

cd /judge0-v1.13.0/judge0-v1.13.0-https
docker-compose down

Check running containers:

docker ps

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9. Download Normal Judge0 Package

Create folder:

cd /
mkdir -p /judge0-normal
cd /judge0-normal

Download Judge0:

wget https://github.com/judge0/judge0/releases/download/v1.13.0/judge0-v1.13.0.zip

Unzip:

unzip judge0-v1.13.0.zip

Go to Judge0 folder:

cd judge0-v1.13.0

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10. Configure Judge0 Passwords

Open config file:

nano judge0.conf

Find these values:

REDIS_PASSWORD=
POSTGRES_PASSWORD=

Set strong passwords:

REDIS_PASSWORD=YourStrongRedisPassword123
POSTGRES_PASSWORD=YourStrongPostgresPassword123

Save file.

In nano:

CTRL + O  -> Enter
CTRL + X  -> Exit

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11. Start Judge0

Start database and Redis first:

docker-compose up -d db redis

Wait 10 seconds:

sleep 10s

Start all Judge0 services:

docker-compose up -d

Check containers:

docker-compose ps

Expected services:

db
redis
server
workers

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12. Test Judge0 Locally

Run:

curl http://localhost:2358/about

Also test:

curl http://localhost:2358/languages

If you get JSON response, Judge0 is running correctly.

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13. Configure Nginx Reverse Proxy

Create Nginx config:

sudo nano /etc/nginx/sites-available/judge.tr**klms.org

Paste this:

server {
    listen 80;
    server_name judge.tr**klms.org;

    client_max_body_size 100M;

    location / {
        proxy_pass http://127.0.0.1:2358;
        proxy_http_version 1.1;

        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;

        proxy_read_timeout 300;
        proxy_connect_timeout 300;
        proxy_send_timeout 300;
    }
}

Save and exit.

Enable site:

sudo ln -s /etc/nginx/sites-available/judge.tr**klms.org /etc/nginx/sites-enabled/

Remove default site:

sudo rm -f /etc/nginx/sites-enabled/default

Test Nginx:

sudo nginx -t

Restart Nginx:

sudo systemctl restart nginx

Now check:

http://judge.tr**klms.org/docs

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14. Install SSL Certificate

Run Certbot:

sudo certbot --nginx -d judge.tr**lms.org

When it asks for redirect, select redirect HTTP to HTTPS.

After SSL installation, open:

https://judge.tr**klms.org/docs

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15. Final URLs

Judge0 API base URL:

https://judge.tr**klms.org

Judge0 API documentation:

https://judge.tr**klms.org/docs

Languages API:

https://judge.tr**klms.org/languages

About API:

https://judge.tr**klms.org/about

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16. Useful Commands

Go to Judge0 folder:

cd /judge0-normal/judge0-v1.13.0

Check running containers:

docker-compose ps

View logs:

docker-compose logs -f

View server logs only:

docker-compose logs -f server

Restart Judge0:

docker-compose restart

Stop Judge0:

docker-compose down

Start Judge0 again:

docker-compose up -d db redis
sleep 10s
docker-compose up -d

Restart Nginx:

sudo systemctl restart nginx

Check Nginx config:

sudo nginx -t

Check SSL renewal:

sudo certbot renew --dry-run

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17. Issue Faced and Solution

Issue

While using:

judge0-v1.13.0-https.zip

Docker showed this error:

failed to bind host port 0.0.0.0:80/tcp: address already in use

Reason

The HTTPS package starts its own Docker Nginx container on port 80.

But our EC2 server already had system Nginx running on port 80.

So two Nginx services were trying to use the same port.

Solution

We stopped the HTTPS package and used the normal Judge0 package:

judge0-v1.13.0.zip

Then we used system Nginx as reverse proxy with Certbot SSL.

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18. Final Deployment Flow Summary

AWS EC2 Ubuntu Server
        ↓
Docker + Docker Compose installed
        ↓
Judge0 normal package installed
        ↓
Judge0 runs internally on port 2358
        ↓
Nginx reverse proxy handles domain
        ↓
Certbot adds SSL
        ↓
Final URL: https://judge.tr**klms.org/docs

Final setup:

Public URL:
https://judge.tr**klms.org

Internal Judge0:
http://127.0.0.1:2358