https://chatgpt.com/share/6a366934-de28-83ec-be2b-be8e15b45fe1

It depends on how the repository is configured.

There are three common deployment models for Hugo on GitHub Pages.

Model 1: User runs Hugo locally (historically common)

The user installs Hugo:

brew install hugo

Builds locally:

hugo

This generates:

public/
├── index.html
├── posts/
└── css/

The user then pushes the generated HTML to GitHub.

git add public/
git commit
git push

GitHub Pages does not run Hugo in this model.

GitHub merely serves:

index.html
style.css
images/*

as static files.

Pipeline:

Markdown
   │
   ▼
Hugo (local machine)
   │
   ▼
HTML
   │
   ▼
GitHub Pages

---

Model 2: GitHub Actions runs Hugo (modern approach)

Today most Hugo sites use GitHub Actions.

Repository contains:

.github/
└── workflows/
    └── hugo.yml

Example:

name: Deploy Hugo

on:
  push:
    branches:
      - main

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4

      - uses: peaceiris/actions-hugo@v3

      - run: hugo

      - uses: actions/upload-pages-artifact@v3

      - uses: actions/deploy-pages@v4

Now user pushes only:

content/post/foo.md

GitHub Actions performs:

hugo

inside GitHub’s build servers.

Pipeline:

Markdown
   │
   ▼
Git Push
   │
   ▼
GitHub Action
   │
   ▼
Hugo Build
   │
   ▼
GitHub Pages

In this case GitHub is effectively executing the Hugo build on behalf of the user.

---

Model 3: GitHub Pages native Jekyll (special case)

GitHub Pages has built-in support for Jekyll:

Jekyll

Repository:

_posts/
_config.yml
index.md

GitHub Pages automatically runs:

Jekyll

without requiring Actions.

Pipeline:

Markdown
   │
   ▼
GitHub Pages
   │
   ▼
Jekyll
   │
   ▼
HTML

Historically GitHub Pages only provided this automatic build service for Jekyll.

Hugo was not automatically executed.

---

How to determine which one a site uses

Look for:

A. GitHub Actions workflow

.github/workflows/

If present and contains:

hugo

then GitHub Actions is building the site.

---

B. Generated HTML committed

If repository contains:

public/
index.html
posts/
css/

and no workflow,

then the author probably builds locally.

---

C. Pages deployment source

On GitHub:

Settings
  → Pages

you will see something like:

Source:
GitHub Actions

or

Deploy from branch

If it says:

GitHub Actions

then GitHub is running the build pipeline.

If it says:

Deploy from branch

then GitHub is only serving files already built elsewhere.

---

What GitHub Pages actually does

GitHub Pages itself is not Hugo.

GitHub Pages is basically:

Static file hosting

similar to:

• Netlify
• Vercel
• Cloudflare

It serves:

HTML
CSS
JavaScript
Images
Fonts

The build step may happen:

1. On your laptop.
2. In GitHub Actions.
3. In another CI/CD system.

For most modern Hugo blogs in 2025–2026, GitHub Actions is the preferred approach, meaning GitHub is indeed running the Hugo pipeline for the user, but only because the user explicitly configured a workflow to do so. GitHub Pages itself does not automatically invoke Hugo the way it historically invoked Jekyll.