docs: Add Matomo analytics and privacy message

[cwhite911]

I've added Matomo analytics to the MKDocs documentation.

https://squidfunk.github.io/mkdocs-material/setup/setting-up-site-analytics/

Matomo was not supported by default, so I created it a custom analytics provider. The site will pop up an Analytics Consent form when a user first visits.

Analytics Consent Form

They can chose to either Accept or Manage settings. If they Accept the form will disappear setting a cookie to {analytics: true, github: true}. These cookies job is just to remember the visitors preference, on browsers that don't allow cookies the user will be prompted every time This is default behavior of material mkdocs.

Manage Settings View

If the user opts out of Matomo no site usage data is sent to Matomo. If they opt-in the following settings are enabled.

 _paq.push(['disableCookies']);
 _paq.push(['enableLinkTracking']);
 _paq.push(['trackPageView']);
 _paq.push(['enableHeartBeatTimer', 10]); // Page needs to be open for 10 seconds before tracking
_paq.push(['setDocumentTitle', document.title]);

The GitHub cookie controls whether the site will make requests to GitHubs API to load repo statistics.

If the user declines the stats will not show.

If they accept and then decline later the stats will continue to show until the session cache is cleared with the last received data from GitHub.

The analytics consent form text is borrowed from the main https://grass.osgeo.org site and links back to our full privacy policy and other relevant resources.

In compliance with GDPR rules the user has the ability to modify their selections at any time by clicking the newly added Privacy Settings link in the footer.

This link will reopen the Analytics Consent form for users to update their settings.

References

Material Mkdocs

• https://squidfunk.github.io/mkdocs-material/setup/ensuring-data-privacy/#cookie-consent
• https://squidfunk.github.io/mkdocs-material/setup/setting-up-site-analytics/
• GitHub Cookie Discussion

Matomo

• https://developer.matomo.org/guides/tracking-javascript-guide#optional-creating-a-custom-opt-out-form
• https://developer.matomo.org/guides/tracking-optout

[cwhite911]

@neteler are you able to configure things in Matomo or is that OSGeo?

[neteler]

We use the GFOSS operated Matomo instance. This is managed by @lucadelu.

[neteler]

FWIW, I have "user access" there: Is there anything I shall configure?

[cwhite911]

I've tested it locally on my own instance of Matomo and everything works. So, once we deploy the new site live you just need to confirm that the traffic from the docs is getting sent to the Matomo server. If everything is working the current setup will blend the docs and the rest of the grass.osgeo.org subdomain analytics together.