Coda

Coda Online Judge Platform

Light-weight contest & practice platform for Coding Of Data structure and Algorithm. This is the homework and exam grading platform used by the NYU course Special Topics: Algorithmic Problem Solving in Spring18 CSCI-UA.0480-004 and Fall18 CSCI-UA.0480-011 (NYU access only).

Install

Suggested nodejs version 8.9.4, npm version 5.6.

Coda has three components: web, server, and judge. Install the parts separately.

npm install # web
npm --prefix ./server install # server & judge

npm --prefix run init-judge # initialize judge

Judge initialization requires permission to talk to Docker daemon. You may need to add the current user to the "docker" group. The init-judge script pulls the docker judge image, which may take a while to download.

Run in development

# web
npm start
# server & judge
npm --prefix ./server run build
npm --prefix ./server start
npm --prefix ./server run judge -- --interval 5 # Judge every 5 seconds

Coda shall then be served at http://localhost:4200.

Run in production

Copy the files at /dist/ and /server/dist/ to your server deployment. Maintain the relative directory structure between web and server.

Configure CODA_ROOT path, server PORT and ALLOW_ORIGIN in /server/.env. See /server/.env.example for an example configuration.

CODA_ROOT must be a valid Coda storage directory. See /server/test_root for a small storage directory example. This directory must be readable and writable for the user that runs the Coda server.

Coda web is served at the given PORT (default 3000). If you need access to HTTP port 80, you need to do port forwarding. If you use Nginx, you can configure proxy as:

server {
  listen 80;
  server_name {YourServerName};

  location / {
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection 'upgrade';
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $http_host;
    proxy_set_header X-Nginx-Proxy true;
    proxy_cache_bypass $http_upgrade;

    proxy_pass http://127.0.0.1:3000;
    proxy_redirect off;
  }
}

Build in production mode:

# web: build it before running the server
npm run build
# server & judge
npm --prefix ./server run serve
npm --prefix ./server run judge -- --interval 5 # Judge every 5 seconds

You can use pm2 to manage your process in production.

# at /server directory
pm2 start dist/server.js
pm2 start dist/judge/judge.js -- --interval 5

Then use pm2 startup to manage your startup script in case the machine reboots.

System config

You can add a file "config.json" at CODA_ROOT to specify system options. CODA_ROOT is the path to all coda data.

{
  "disableSource": true,
  "judgeProblemsets": ["problemset1", "problemset2"]
}

disableSource: When true, all users can view their own submissions in all problemsets, including those that have ended.

judgeProblemsets: Only those problemsets in the list are judged. Give null if every problemset is to be judged.

Problem config

Each problem is a folder under CODA_ROOT/problem/{problem_id}. The content of the problem folder follows the problemtools format. More documentation on problemtools can be found here.

Under the problem folder, there should be a coda json config file:

{
  "id": "aplusb",
  "title": "A Plus B",
  "timeLimit": 1,
  "subtasks": ["all"],
  "subtaskOnlySamples": []
}

This file specifies the problem's id, title, time limit, etc. If the problem does not have subtasks, it should have "all" in the subtasks list.

Problem subtasks

If a problem contains subtasks, its config file looks as follows:

{
  "id": "aplusb",
  "title": "A Plus B",
  "timeLimit": 2,
  "subtasks": ["easy", "hard"],
  "subtaskOnlySamples": [
    { "sample": "003-sample-hard", "subtasks": ["hard"] }
  ]
}

If subtaskOnlySamples are specified, a message will be displayed in the web interface letting the user know that certain sample cases only belong to certain subtasks.

For a problemwith subtasks, the problem package should include a separate sub-folder for each subtask. The structure of the problem package would be as follows:

problem_id -+--- problem_statement
            |--- data --- sample (sample is needed for problem statement)
            |--- small -+--- input_format_validators
            |           |--- data -+--- sample
            |           |          |--- secret
            |           |--- submissions
            |
            |--- large -+ ... (same as small)

The files are structured as above to achieve minimal duplicate sources (e.g. only keep one copy of problem statement). Input format validators, data and submissions shall be different for each subtask. If you run problemtools, each subtask folder must be verfied individually.

Problemset config

Each problemset is a folder under CODA_ROOT/{problemset_id}. This folder can be initialized with a single json config file like this:

{
  "id": "hw1",
  "title": "Homework 1",
  "runMode": "STANDARD",
  "judgeMode": "OPEN",
  "penaltyMode": "SCORE",
  "scoreboardMode": "ANONYMOUS",
  "startTime": "Wed Sep 5 2018 13:00:00 GMT-0400 (EDT)",
  "endTime": "Wed Sep 12 2018 13:00:00 GMT-0400 (EDT)",
  "freebies": 5,
  "showCaseNumber": true,
  "allowGroups": ["fall18"],
  "problems": [
    {
      "number": "A",
      "id": "aplusb",
      "subtasks": [
        { "id": "all", "score": 40 }
      ]
    },
    {
      "number": "B",
      "id": "simplesum",
      "subtasks": [
        { "id": "small", "score": 30 },
        { "id": "large", "score": 30 }
      ]
    },
    {
      "number": "C",
      "id": "rockpaperscissors",
      "subtasks": [
        { "id": "all", "score": 40 }
      ]
    }
  ]
}

Once the problem starts, user submissions will be saved inside this folder. A submissions.json will be created to index all user submissions. A verdicts.json will be created for judged results.

User signup

You can prepare a json file that contains a list of emails, e.g.

[
  "[email protected]",
  "[email protected]"
]

Then use the gen-users script to create a users.json. Place the users.json under the CODA_ROOT. Set EMAIL_* environment variables (see .env.example). Finally use the email-signup script to send each user an email with an invitation code for signup.

# at /server
npm run gen-users -- --emails emails.json
cp users.json $CODA_ROOT/users.json
npm run email-signup

Export source code

You can export all submission source to a folder.

npm run export-code -- --problemset {problemsetId}