Single out Tor Browser users in Matomo

To summarize our options, the pros and cons, to single out, at least partly, Tor Browser users:

1. Use server log with IP addresses

- (+) Will take into account people without JavaScript.
- (-) People going out through the same exit node will appear as a
single visit.

2. Use the JavaScript and cookie from Piwik

- (-) We won’t take into account people without JavaScript.

- (-) Have to add a consent message as of the Cookie Law.
- (+) Will be able to differentiate Tor Browser users going out through
the same exit node.

3. Use the JavaScript only from Piwik

- (-) We won’t take into account people without JavaScript.

- (+) Probably won’t be able to differentiate Tor Browser users going out through the same exit node.
- (+) Don’t have to change our current server log policy (= bother boum.org).

In all cases, we can use the IP anonymization feature of Piwik on top of that (and delete the server logs for example).

Temporary conclusion: Options 1 and 3 seems the best options given the European legislation. 1 would take into account people without JavaScript so might be better on the long term. But 3 doesn’t imply changes on boum.org so could be done right now.

Parent Task: #12562 (closed)

Original created by @sajolida on 12729 (Redmine)