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Writing Legacy Authentication Backends

Deprecated since version 1.6: Legacy authentication backends are deprecated in 1.6. See Writing Authentication Backends.

Overview

Authentication in Review Board is handled by classes called Authentication Backends. They perform the tasks of looking up users from some database or server, authenticating against it given user credentials, and creating local representations of the users in Review Board’s database.

Review Board provides local database, NIS, LDAP and Active Directory backends out of the box. New ones can be written to work with other types of authentication schemes.

Authentication Classes

An Authentication Backend class is a simple class inheriting from object, which provides the following methods:

authenticate

authenticate(username, password)
Parameters:
  • username – The user’s username.
  • password – The user’s password.
Return type:

The authenticated user, if authentication succeeds. On failure, None.

Authenticates the user against a database or server.

This is responsible for making any necessary communication with the database or server and determining the validity of the credentials passed.

If the credentials are invalid, the function must return None, which will allow it to fall back to the next authentication backend in the chain (or fail, if this is the last authentication backend).

If the credentials are valid, the function must return a valid User. Generally, rather than constructing one itself, it should call its own get_or_create_user() with the username.

To help with debugging, this function should log any errors in communication using Python’s logging support.

The function may need to strip whitespace from the username before authentication. If the server itself strips whitespace when authenticating, but this function does not, it can lead to duplicate users in the database.

get_or_create_user

get_or_create_user(username)
Parameters:username – The user’s username.
Return type:The user, if it exists. Otherwise, None.

Looks up or creates a User based on information from the database or server.

This tends to follow the pattern of:

username = username.strip()

try:
    user = User.objects.get(username=username)
except User.DoesNotExist:
    # Construct a user from the database...
    return user

Like authenticate(), this will look up the user from the database or server. However, it will not verify anything other than the username. It also must make sure to strip the username.

This function is used both when logging in and when adding a user to a review request as a reviewer. In the latter case, Review Board will look up the user using the authentication backend in order to see if the user exists and can be added.

get_user

get_user(user_id)
Parameters:user_id – The ID of the user in the database.
Return type:The user, if it exists. Otherwise, None.

This is a simple function that just looks up the User in the database, given the numeric ID. This should always simply contain:

return get_object_or_none(User, pk=user_id)

Note: get_object_or_none() comes from djblets.util.misc.

Installing the Authentication Backend

The authentication backend should be packaged as a standard Python egg. This includes creating a setup.py and making a proper Python module that includes your authentication backend.

Once this is Python package is installed on the system running Review Board, you can change the Authentication type in Review Board to Custom and specify the Python path for your authentication backend class.