Add config variables for enabling terms auth and the policy name (#4142)

So people can still collect consent the old way if they want to.

1 files changed, 36 insertions, 4 deletions

diff --git a/docs/consent_tracking.md b/docs/consent_tracking.md
index 3634d13d4f..c586b5f0b6 100644
--- a/docs/consent_tracking.md
+++ b/docs/consent_tracking.md
@@ -81,9 +81,40 @@ should be a matter of `pip install Jinja2`. On debian, try `apt-get install
 python-jinja2`.
 
 Once this is complete, and the server has been restarted, try visiting
-`https://<server>/_matrix/consent`. If correctly configured, you should see a
-default policy document. It is now possible to manually construct URIs where
-users can give their consent.
+`https://<server>/_matrix/consent`. If correctly configured, this should give
+an error "Missing string query parameter 'u'". It is now possible to manually
+construct URIs where users can give their consent.
+
+### Enabling consent tracking at registration
+
+1. Add the following to your configuration:
+
+   ```yaml
+   user_consent:
+     require_at_registration: true
+     policy_name: "Privacy Policy" # or whatever you'd like to call the policy
+   ```
+
+2. In your consent templates, make use of the `public_version` variable to
+   see if an unauthenticated user is viewing the page. This is typically
+   wrapped around the form that would be used to actually agree to the document:
+
+   ```
+   {% if not public_version %}
+     <!-- The variables used here are only provided when the 'u' param is given to the homeserver -->
+     <form method="post" action="consent">
+       <input type="hidden" name="v" value="{{version}}"/>
+       <input type="hidden" name="u" value="{{user}}"/>
+       <input type="hidden" name="h" value="{{userhmac}}"/>
+       <input type="submit" value="Sure thing!"/>
+     </form>
+   {% endif %}
+   ```
+
+3. Restart Synapse to apply the changes.
+
+Visiting `https://<server>/_matrix/consent` should now give you a view of the privacy
+document. This is what users will be able to see when registering for accounts.
 
 ### Constructing the consent URI
 
@@ -108,7 +139,8 @@ query parameters:
 
 Note that not providing a `u` parameter will be interpreted as wanting to view
 the document from an unauthenticated perspective, such as prior to registration.
-Therefore, the `h` parameter is not required in this scenario.
+Therefore, the `h` parameter is not required in this scenario. To enable this
+behaviour, set `require_at_registration` to `true` in your `user_consent` config.
 
 
 Sending users a server notice asking them to agree to the policy