mkdocs-material/docs/setup/ensuring-data-privacy.md

template
overrides/main.html

Ensuring data privacy

Material for MkDocs makes compliance with data privacy regulations a breeze, as it offers a native cookie consent solution to seek explicit consent from users before setting up tracking. Additionally, external assets can be automatically bundled as part of the build process.

Configuration

Built-in privacy

:octicons-heart-fill-24:{ .mdx-heart } Insiders{ .mdx-insiders } · :octicons-tag-24: insiders-4.9.0 · :octicons-cpu-24: Plugin · :octicons-beaker-24: Experimental

The built-in privacy plugin automatically downloads external assets as part of the build process and stores them alongside your documentation. Add the following lines to mkdocs.yml:

plugins:
  - privacy # (1)!

1. Note that the privacy plugin should be located at the end of the list of plugins, as it will scan the resulting HTML for links to download and replace. If a plugin after the privacy plugin adds further external assets, these assets will not be downloaded.

The following configuration options are available:

download{ #download }

:octicons-milestone-24: Default: true – This option specifies whether the plugin should download external assets. If you want to switch the plugin off, e.g. for local builds, use an environment variable:

plugins:
  - privacy:
      download: !ENV [DOWNLOAD, false]

download_directory{ #download-directory }

:octicons-milestone-24: Default: assets/externals – This option specifies where the downloaded external assets will be stored. It's normally not necessary to change this option:

plugins:
  - privacy:
      download_directory: assets/externals

??? question "Why can't Material for MkDocs bundle all assets by design?"

The primary reason why Material for MkDocs can't just bundle all of its own
assets is the integration with [Google Fonts], which offers over a thousand
different fonts that can be used to render your documentation. Most of the
fonts include several weights and are split up into different character sets 
to keep the download size small, so the browser only downloads what is
really needed. For Roboto, our default [regular font], this results in [28
`*.woff2` files in total][example].

If Material for MkDocs would bundle all font files, the download size would
be in the hundreds of megabytes, slowing down automated builds. Furthermore, 
authors might add external assets like third-party scripts or stylesheets 
that would need to be remembered to be defined as further local assets.

This is the very reason the [built-in privacy] plugin exists — it automates
the process of downloading all external assets manually to ensure compliance
with GDPR. Note that there are some [technical limitations].

How it works

The built-in privacy plugin scans the resulting HTML for links to external resources, including external scripts, style sheets, images and web fonts, and downloads them to bundle them with your documentation site. Every URL refering to an external resource, no matter if part of a template or Markdown file is then replaced with the URL to the local copy. An example:

<script src="https://example.com/script.js"></script>

The external script is downloaded, and the link is replaced with:

<script src="assets/externals/example.com/script.js"></script>

Style sheets are scanned for external url(...) references, e.g. images and web fonts, which are then also downloaded and bundled with your documentation site. This means that Google Fonts can be configured in mkdocs.yml as usual, as the built-in privacy plugin automatically downloads and bundles all dependent resources.

As a third measure, preconnect hints used for DNS pre-fetching which might also leak the visitors IP address to a third party are automatically removed during the build process.

???+ example "Expand to inspect example"

For the official documentation, the [built-in privacy] plugin downloads the
following resources:

``` { .sh id="example" }
.
└─ assets/externals/
   ├─ cdnjs.cloudflare.com/ajax/tablesort/5.2.1/tablesort.min.js
   ├─ fonts.googleapis.com/css
   ├─ fonts.gstatic.com/s/
   │  ├─ roboto/v29/
   │  │  ├─ KFOlCnqEu92Fr1MmWUlfChc4EsA.woff2
   │  │  ├─ KFOmCnqEu92Fr1Mu7mxKOzY.woff2
   │  │  ├─ KFOlCnqEu92Fr1MmSU5fCBc4EsA.woff2
   │  │  ├─ KFOmCnqEu92Fr1Mu4mxK.woff2
   │  │  ├─ KFOkCnqEu92Fr1Mu51xEIzIFKw.woff2
   │  │  ├─ KFOlCnqEu92Fr1MmSU5fBxc4EsA.woff2
   │  │  ├─ KFOkCnqEu92Fr1Mu51xLIzIFKw.woff2
   │  │  ├─ KFOlCnqEu92Fr1MmWUlfBBc4.woff2
   │  │  ├─ KFOlCnqEu92Fr1MmWUlfBxc4EsA.woff2
   │  │  ├─ KFOkCnqEu92Fr1Mu51xFIzIFKw.woff2
   │  │  ├─ KFOlCnqEu92Fr1MmSU5fChc4EsA.woff2
   │  │  ├─ KFOlCnqEu92Fr1MmWUlfCBc4EsA.woff2
   │  │  ├─ KFOmCnqEu92Fr1Mu7GxKOzY.woff2
   │  │  ├─ KFOkCnqEu92Fr1Mu51xMIzIFKw.woff2
   │  │  ├─ KFOlCnqEu92Fr1MmSU5fCxc4EsA.woff2
   │  │  ├─ KFOlCnqEu92Fr1MmWUlfCRc4EsA.woff2
   │  │  ├─ KFOmCnqEu92Fr1Mu7WxKOzY.woff2
   │  │  ├─ KFOmCnqEu92Fr1Mu72xKOzY.woff2
   │  │  ├─ KFOlCnqEu92Fr1MmWUlfABc4EsA.woff2
   │  │  ├─ KFOkCnqEu92Fr1Mu51xHIzIFKw.woff2
   │  │  ├─ KFOmCnqEu92Fr1Mu5mxKOzY.woff2
   │  │  ├─ KFOlCnqEu92Fr1MmSU5fABc4EsA.woff2
   │  │  ├─ KFOkCnqEu92Fr1Mu51xIIzI.woff2
   │  │  ├─ KFOmCnqEu92Fr1Mu4WxKOzY.woff2
   │  │  ├─ KFOkCnqEu92Fr1Mu51xGIzIFKw.woff2
   │  │  ├─ KFOlCnqEu92Fr1MmWUlfCxc4EsA.woff2
   │  │  ├─ KFOlCnqEu92Fr1MmSU5fBBc4.woff2
   │  │  └─ KFOlCnqEu92Fr1MmSU5fCRc4EsA.woff2
   │  └─ robotomono/v13/
   │     ├─ L0xuDF4xlVMF-BfR8bXMIhJHg45mwgGEFl0_3vq_R-W4Ep0.woff2
   │     ├─ L0xuDF4xlVMF-BfR8bXMIhJHg45mwgGEFl0_3vq_QOW4Ep0.woff2
   │     ├─ L0xuDF4xlVMF-BfR8bXMIhJHg45mwgGEFl0_3vq_SuW4Ep0.woff2
   │     ├─ L0xuDF4xlVMF-BfR8bXMIhJHg45mwgGEFl0_3vq_ROW4.woff2
   │     ├─ L0xuDF4xlVMF-BfR8bXMIhJHg45mwgGEFl0_3vq_SeW4Ep0.woff2
   │     └─ L0xuDF4xlVMF-BfR8bXMIhJHg45mwgGEFl0_3vq_S-W4Ep0.woff2
   └─ polyfill.io/v3/polyfill.min.js
```

Caching recommended

All downloaded files are written to the .cache directory, significantly reducing the duration of subsequent builds as only replacements need to be carried out. You might want to:

1. Ignore the .cache directory in your project, by adding it to .gitignore.

2. When building your site for publishing, use a build cache to save the .cache directory in between builds. Taking the example from the publishing guide, add the following lines:

   name: ci
     on:
       push:
         branches:
           - master
           - main
     jobs:
       deploy:
         runs-on: ubuntu-latest
         steps:
           - uses: actions/checkout@v2
           - uses: actions/setup-python@v2
             with:
               python-version: 3.x
           - uses: actions/cache@v2
             with:
               key: ${{ github.ref }}
               path: .cache
           - run: pip install mkdocs-material
           - run: mkdocs gh-deploy --force
   

Limitations

Note that dynamically created URLs as part of scripts are not detected, and thus cannot be automatically downloaded. The built-in privacy plugin does not execute scripts – it can only detect complete URLs to download and replace.