[ckan-dev] integrating login between ckan and drupal

[David Read]

(cc'ing ckan-dev as others may be interested)

At data.gov.uk, users can log in and the account is used across both
Drupal and CKAN. We tried to have as few integration points between
Drupal and CKAN as possible because it really adds to the complexity,
but this was a key one to allow both the public and our hundreds of
publisher users to interact seamlessly. I wrote more about this
general Drupal/CKAN integration approach here:
http://data.gov.uk/blog/integrating-ckan-and-drupal

The design works nicely with CKAN 1.7.1 and Drupal 6, and I expect it
to work fine with CKAN 2 and Drupal 7, but haven't tested it. It was
not possible to do this functionality as a repoze.who plugin, and it
man-handles repoze somewhat to get the desired outcome.

Essentially, a user logs into Drupal as normal. Then when the user
clicks on a CKAN page, a new piece of middleware sees the Drupal
cookie in the request, and if it is valid then it tells CKAN's
auth_tkt to log the user in (creating a CKAN cookie). CKAN needs its
own User object, so if it doesn't exist then one is created. The
user's name, email address and roles (permissions) are copied from the
Drupal world to the CKAN User object. By setting the REMOTE_USER
variable, the request continues, now logged in. Subsequent requests
will be logged in by auth_tkt.

When checking the Drupal cookie, it checks it is for the correct
hostname and then makes a call to a Drupal XMLRPC API (that was put
together by our Drupal team and I don't know anything more) with the
session ID: get_user_id_from_session_id(). From the Drupal "user ID"
(node ID) we then ask Drupal get_user_properties() to get name, roles
etc.

Logging out of Drupal causes the cookie checking to fail and it logs
out out of CKAN too.

There are a few caveats to the system as it stands:
a) when roles are given to a user in the Drupal world, the CKAN user
needs to relogin to receive them. We only use it for sysadmin role
(others are pure-CKAN roles), so that is not really an issue for us.
b) https is not covered yet, but shouldn't be difficult
c) CKAN doesn't create the user object until that user clicks on an
CKAN page. This may not happen before an admin tries to give them CKAN
permissions, which causes problems. Currently we have a warning
message, but this could be solved with a bit more work.

There are several data.gov.uk-specific assumptions in the code: the
names of the roles we are interested in, users copied from Drupal are
called user_d<number>. And of course the Drupal and CKAN sites are on
the same hostname to share the cookies.

The code is here:
https://github.com/datagovuk/ckanext-dgu/blob/master/ckanext/dgu/authentication/drupal_auth.py

As far as configuration goes, in our ckan .ini we set the values for:
dgu.xmlrpc_username
dgu.xmlrpc_password
dgu.xmlrpc_domain

and add 'dgu_drupal_auth' to ckan.plugins

You can see in our plugin.py how to create the DrupalAuthPlugin to
allow the middleware to be inserted into the request handling stack:
https://github.com/datagovuk/ckanext-dgu/blob/master/ckanext/dgu/plugin.py

We also added a repoze.who plugin to ensure that 401 'not allowed'
requests sends the user to a custom 'not_authorized' web page, rather
than the CKAN log-in form. To achieve that we added the plugin in
who.ini:

[plugin:dgu_auth_tkt]
use = ckanext.dgu.authentication.auth_tkt:make_plugin

In [plugin:friendlyform] and [plugin:openid] sections:
rememberer_name = dgu_auth_tkt

and in [identifiers]:
    dgu_auth_tkt
instead of
    auth_tkt

David

On 26 March 2013 10:54, Irina Bolychevsky <irina.bolychevsky at okfn.org> wrote:
> Hey David,
>
> Hope you're well. We were wondering if you have any documentation on how you
> guys set up the shared login for the drupal and ckan parts of data.gov.uk
> (or, how is this actually configured?).
>
> If not, any chance we can pick your brain on this? A post somewhere would
> likely be popular!
>
> Cheers,
> Ira
>
> --
>
> Irina Bolychevsky
> CKAN Product Owner
>
> The Open Knowledge Foundation (http://www.okfn.org)
>
> More information on CKAN: http://ckan.org/
>
> Follow me on Twitter: http://twitter.com/shevski