Designing an Open Source Content Management System (CMS)

A Content Management System (CMS) is a software platform that allows users to create, manage, and modify digital content without needing to know complex coding. It’s commonly used to build websites, blogs, and digital publishing platforms.

My first content management system was Wordpress, then Moodle, Blackboard, Drupal. Today you have shopify, squarespace, webflow as the modern choices. CMS's are very common tools.

Example: Imagine you're a small business owner. You want to launch a website, but you don’t have time to code from scratch. A CMS like WordPress lets you easily design your site, add content, and keep it updated without touching the underlying code.

💡
Did you know most publishing and media companies require a CMS to manage and publish content.

A CMS typical build

In this article, we’ll learn how to design a scalable open source CMS that can handle high traffic, support plugins, and provide an intuitive user interface for content creation and management.

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What do I know about building a CMS?

I've worked with several! Built many!

1. Requirements Gathering 📝

💡
Remember in any system design interview break down the requirements into these two categories.

Functional Requirements:

  • Content Creation: 🖋️ Users must be able to create, edit, and publish content easily (e.g., blogs, articles, media).
  • User Roles & Permissions: 🛡️ Support multiple user roles (e.g., admin, editor, author) with different access levels.
  • Theme & Plugin Support: 🎨🛠️ Enable users to extend CMS functionality with themes and plugins.(which could be optional)
  • Version Control: 🔄 Track changes in content and allow rollbacks.
  • SEO & Analytics: 📊 Integrate tools to help optimize content for search engines and track performance.
  • Reliable Content Storage: 🫙 Build a system where users trust to use the CMS as their sole content storage. We don't want them writing in google docs then copying/pasting. (often overlooked but long term approach)

Non-Functional Requirements:

  • Scalability: 📈 Handle thousands of content creators and millions of visitors per day.
  • High Availability: ⏳ Ensure minimal downtime so that content is always accessible.
  • Security: 🔒 Protect against common threats like SQL injections, cross-site scripting, and unauthorized access.
  • Performance: ⚡ Optimize for fast loading times and low latency, even during traffic spikes.

2. Scale Estimation 📐

Before diving into design, let’s estimate the scale:

  • Users: 🧑‍💻 Assume the CMS serves 5 million active users.
  • Content per User: On average, each user publishes 10 articles per month.
  • Peak Load: 📈 Assume 1 million visitors in a minute during high-traffic periods (e.g., breaking news).

This means the CMS should handle:

  • Articles per month: 📰 5 million x 10 = 50 million articles per month.
  • Peak requests per second: ⏱️ 1 million / 60 = ~16,666 requests/second.

Storage Requirements:

  • Assume average article size: 50KB
  • Monthly storage for articles: 🗄️ 50 million x 50KB = ~2.5TB

3. High-Level Design 🏗️

Our system will consist of the following components:

  • CMS Core: 🧠 The heart of the system, responsible for managing content, user roles, themes, and plugins.
  • Content Database: 📂 Stores all content, including articles, media, metadata, and revisions.
  • User Management: 👥 Manages user accounts, roles, and permissions.
  • Plugin & Theme Manager: 🔌🎨 Enables users to install and manage plugins and themes to extend functionality.
  • Caching Layer: ⚙️ Speeds up content delivery by caching frequently accessed content.
  • SEO & Analytics Module: 🔍📊 Integrates tools to optimize content and track site performance.

4. Detailed Design 🛠️

Step 1: Content Creation & Management

  • Users create content using a rich text editor with support for media uploads (images, videos, documents).
{
  "id": "123456",
  "title": "How to Build a Scalable CMS",
  "slug": "build-scalable-cms",
  "author": {
    "id": "7890",
    "name": "John Doe",
    "role": "author"
  },
  "content": {
    "body": "<p>Welcome to our guide on building a scalable CMS...</p>",
    "media": [
      {
        "type": "image",
        "url": "https://example.com/image1.jpg",
        "alt_text": "CMS Architecture"
      }
    ]
  },
  "status": "published", 
  "tags": ["CMS", "development", "scalability"],
  "created_at": "2024-09-17T14:00:00Z",
  "updated_at": "2024-09-18T12:30:00Z",
  "published_at": "2024-09-18T13:00:00Z",
  "meta": {
    "description": "A detailed guide on building a scalable CMS.",
    "keywords": ["CMS", "scalability", "web development"]
  },
  "seo_score": 85,
  "comments": [
    {
      "id": "987",
      "user": "Jane Smith",
      "content": "This article is very helpful!",
      "created_at": "2024-09-18T14:10:00Z"
    }
  ]
}

Step 2: User Management & Permissions

  • Admins can create and manage user roles with customizable permissions (e.g., who can publish vs. edit only).
{
  "id": "7890",
  "name": "John Doe",
  "email": "johndoe@example.com",
  "role": "author",
  "permissions": {
    "can_publish": true,
    "can_edit": true,
    "can_delete": false
  },
  "created_at": "2024-01-15T10:00:00Z",
  "last_login": "2024-09-17T08:30:00Z",
  "profile_image": "https://example.com/johndoe.jpg"
}

Step 3: Plugins & Themes

  • The CMS allows users to install plugins to add functionality (e.g., social sharing, contact forms) or change the website’s design via themes.

Step 4: SEO Optimization

  • The CMS includes an SEO module to help users optimize their articles for search engines by adding meta tags, generating sitemaps, and checking keyword density.

Step 5: Caching & Performance

  • A caching system (e.g., Redis, Varnish) is integrated to store frequently accessed pages, reducing load on the CMS database during high-traffic periods.

5. Key Features to Address 🔑

Scalability:

  • The system should be designed to handle high traffic through load balancing and horizontal scaling.

Security:

  • Ensure strong authentication (e.g., OAuth2) and protect against common vulnerabilities like XSS and CSRF attacks.

Performance:

  • Caching and Content Delivery Network (CDN) integration will help deliver content faster to users globally.

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I hope you have a lovely day!

See you soon,

Caleb 'TechDad' ✌🏾