NAME

    Dancer2::Plugin::Auth::Extensible::Provider::Database - authenticate
    via a database

DESCRIPTION

    This class is an authentication provider designed to authenticate users
    against a database, using Dancer2::Plugin::Database to access a
    database.

    Crypt::SaltedHash is used to handle hashed passwords securely; you
    wouldn't want to store plain text passwords now, would you? (If your
    answer to that is yes, please reconsider; you really don't want to do
    that, when it's so easy to do things right!)

    See Dancer2::Plugin::Database for how to configure a database
    connection appropriately; see the "CONFIGURATION" section below for how
    to configure this authentication provider with database details.

    See Dancer2::Plugin::Auth::Extensible for details on how to use the
    authentication framework, including how to pick a more useful
    authentication provider.

CONFIGURATION

    This provider tries to use sensible defaults, so you may not need to
    provide much configuration if your database tables look similar to
    those in the "SUGGESTED SCHEMA" section below.

    The most basic configuration, assuming defaults for all options, and
    defining a single authentication realm named 'users':

        plugins:
            Auth::Extensible:
                realms:
                    users:
                        provider: 'Database'

    You would still need to have provided suitable database connection
    details to Dancer2::Plugin::Database, of course; see the docs for that
    plugin for full details, but it could be as simple as, e.g.:

        plugins:
            Auth::Extensible:
                realms:
                    users:
                        provider: 'Database'
            Database:
                driver: 'SQLite'
                database: 'test.sqlite'
                on_connect_do: ['PRAGMA foreign_keys = ON']
                dbi_params:
                    PrintError: 0
                    RaiseError: 1

    A full example showing all options:

        plugins:
            Auth::Extensible:
                realms:
                    users:
                        provider: 'Database'
                        # optionally set DB connection name to use (see named
                        # connections in Dancer2::Plugin::Database docs)
                        db_connection_name: 'foo'
    
                        # Optionally disable roles support, if you only want to check
                        # for successful logins but don't need to use role-based access:
                        disable_roles: 1
    
                        # optionally specify names of tables if they're not the defaults
                        # (defaults are 'users', 'roles' and 'user_roles')
                        users_table: 'users'
                        roles_table: 'roles'
                        user_roles_table: 'user_roles'
    
                        # optionally set the column names (see the SUGGESTED SCHEMA
                        # section below for the default names; if you use them, they'll
                        # Just Work)
                        users_id_column: 'id'
                        users_username_column: 'username'
                        users_password_column: 'password'
                        roles_id_column: 'id'
                        roles_role_column: 'role'
                        user_roles_user_id_column: 'user_id'
                        user_roles_role_id_column: 'roles_id'

    See the main Dancer2::Plugin::Auth::Extensible documentation for how to
    configure multiple authentication realms.

SUGGESTED SCHEMA

    If you use a schema similar to the examples provided here, you should
    need minimal configuration to get this authentication provider to work
    for you.

    The examples given here should be MySQL-compatible; minimal changes
    should be required to use them with other database engines.

 users table

    You'll need a table to store user accounts in, of course. A suggestion
    is something like:

        CREATE TABLE users (
            id       INTEGER     AUTO_INCREMENT PRIMARY KEY,
            username VARCHAR(32) NOT NULL       UNIQUE KEY,
            password VARCHAR(40) NOT NULL
        );

    You will quite likely want other fields to store e.g. the user's name,
    email address, etc; all columns from the users table will be returned
    by the logged_in_user keyword for your convenience.

 roles table

    You'll need a table to store a list of available roles in (unless
    you're not using roles - in which case, disable role support (see the
    "CONFIGURATION" section).

        CREATE TABLE roles (
            id    INTEGER     AUTO_INCREMENT PRIMARY KEY,
            role  VARCHAR(32) NOT NULL
        );

 user_roles table

    Finally, (unless you've disabled role support) you'll need a table to
    store user <-> role mappings (i.e. one row for every role a user has;
    so adding extra roles to a user consists of adding a new role to this
    table). It's entirely up to you whether you use an "id" column in this
    table; you probably shouldn't need it.

        CREATE TABLE user_roles (
            user_id  INTEGER  NOT NULL,
            role_id  INTEGER  NOT NULL,
            UNIQUE KEY user_role (user_id, role_id)
        );

    If you're using InnoDB tables rather than the default MyISAM, you could
    add a foreign key constraint for better data integrity; see the MySQL
    documentation for details, but a table definition using foreign keys
    could look like:

        CREATE TABLE user_roles (
            user_id  INTEGER, FOREIGN KEY (user_id) REFERENCES users (id),
            role_id  INTEGER, FOREIGN KEY (role_id) REFERENCES roles (id),
            UNIQUE KEY user_role (user_id, role_id)
        ) ENGINE=InnoDB;

ATTRIBUTES

 dancer2_plugin_database

    Lazy-loads the correct instance of Dancer2::Plugin::Database which
    handles the following methods:

      * plugin_database

      This corresponds to the database keyword from
      Dancer2::Plugin::Database.

 database

    The connected "plugin_database" using "db_connection_name".

 db_connection_name

    Optional.

 users_table

    Defaults to 'users'.

 users_id_column

    Defaults to 'id'.

 users_username_column

    Defaults to 'username'.

 users_password_column

    Defaults to 'password'.

 roles_table

    Defaults to 'roles'.

 roles_id_column

    Defaults to 'id'.

 roles_role_column

    Defaults to 'role'.

 user_roles_table

    Defaults to 'user_roles'.

 user_roles_user_id_column

    Defaults to 'user_id'.

 user_roles_role_id_column

    Defaults to 'role_id'.

METHODS

 authenticate_user $username, $password

 create_user

 get_user_details $username

 get_user_roles $username

 set_user_details

 set_user_password

COOKBOOK

 Handle locked or disabled user accounts

    (contributed by PerlDuck, Borodin and simbabque via Stack Overflow
    <https://stackoverflow.com/questions/46746864>)

    It's a good practice to not delete certain data, like user accounts.
    But what do you do when you want to get rid of a user? Maybe an
    employee left or was temporary suspended, or a user did not pay their
    subscription fee. In those cases you would want the user data to stay
    around, but they should not be able to log in any more.

    Let's say there is a column disabled in an already existing user table.
    It might hold a timestamp for when the user was disabled, and be NULL
    if the user is active. By default, Dancer2::Plugin::Auth::Extensible
    will give you this information as part of the user data, but to check
    if the user is allowed to proceed would happen after the password has
    been checked and they have already been logged in.

    The following sections will describe two different ways of implementing
    this. The first one is easier to implement, but only allows read
    operations on the user table, while the second one requires a little
    more effort, but will allow almost all operations to work. If you need
    even more flexibility you will have to subclass and add a bit more
    logic.

  ... without changing any code

    An easy way to achieve this is by adding a new view to your database
    that only shows active users. Let's look at the following example
    database.

        -- user table
        CREATE TABLE users (
            id       INTEGER     PRIMARY KEY AUTOINCREMENT,
            username VARCHAR(32) NOT NULL UNIQUE,
            password VARCHAR(40) NOT NULL,
            disabled TIMESTAMP   NULL
        );
    
        -- active user view
        CREATE VIEW active_users (id, username, password) AS
            SELECT id, username, password FROM users WHERE disabled IS NULL;
    
        -- some data
        INSERT INTO users ( username, password, disabled )
        VALUES  ( 'Alice', 'test', null),
                ( 'Bob', 'test', '2017-10-01 10:10:10');

    Now all you need to do is change the "users_table" setting to point to
    active_users instead of users.

        # config.yml
        plugins:
            Auth::Extensible:
                realms:
                    users:
                        provider: 'Database'
                        users_table: 'active_users'

    That's it. Your application will now only let active users log in,
    because it has no way of knowing about the others. Only Alice will be
    able to log in, but Bob has been disabled and the application will not
    allow him to log in.

    But be aware that this comes with a few drawbacks. If you want to use
    Dancer2::Plugin::Auth::Extensible to also update user information, this
    is now no longer possible because in most database engines you cannot
    write data into a view.

  ... by creating a subclass of this database provider

    The alternative is to subclass this provider to add a little bit of
    logic. You can add code to exclude users directly when the user data is
    fetched, even before Dancer2::Plugin::Auth::Extensible verifies the
    password. This way, inactive users can easily be discarded.

    The following code is an example implementation specifically for the
    user table outlined in the alternative solution above.

        package Provider::Database::ActiveOnly;
    
        use Moo;
        extends 'Dancer2::Plugin::Auth::Extensible::Provider::Database';
    
        around 'get_user_details' => sub {
            my $orig = shift;
            my $self = shift;
    
            # do nothing if we there was no user
            my $user = $self->$orig(@_) or return;
    
            # do nothing if the user is disabled
            return if $user->{disabled};
    
            return $user;
        };
    
        1;

    The code uses an around modifier from Moo to influence the
    get_user_details method, so users that are disabled are never found.

    To enable this new provider, you need to change the provider setting in
    your configuration.

        # config.yml
        plugins:
            Auth::Extensible:
                realms:
                    users:
                        provider: 'Provider::Database::ActiveOnly'
                        users_table: 'users'  # this is the default

    With this custom subclass your application will be able to perform
    write operations on active users, including making them inactive.
    However, inactive users will be invisible to
    Dancer2::Plugin::Auth::Extensible, so you cannot use this to turn
    inactive users back on.

    If you want that functionality, you will have to add a bit more logic
    to your subclass. A possible approach could be to replace the
    "authenticate_user" method.

AUTHOR

    David Precious, <davidp at preshweb.co.uk>

    Dancer2 port of Dancer::Plugin::Auth::Extensible by:

    Stefan Hornburg (Racke), <racke at linuxia.de>

    Conversion to Dancer2's new plugin system in 2016 by:

    Peter Mottram (SysPete), <peter at sysnix.com>

BUGS / FEATURE REQUESTS

    This is an early version; there may still be bugs present or features
    missing.

    This is developed on GitHub - please feel free to raise issues or pull
    requests against the repo at:
    https://github.com/PerlDancer/Dancer2-Plugin-Auth-Extensible-Provider-Database

ACKNOWLEDGEMENTS

    From Dancer2::Plugin::Auth::Extensible:

    Valuable feedback on the early design of this module came from many
    people, including Matt S Trout (mst), David Golden (xdg), Damien
    Krotkine (dams), Daniel Perrett, and others.

    Configurable login/logout URLs added by Rene (hertell)

    Regex support for require_role by chenryn

    Support for user_roles looking in other realms by Colin Ewen (casao)

    LDAP provider added by Mark Meyer (ofosos)

    Documentation fix by Vince Willems.

    Henk van Oers (GH #8, #13).

    Andrew Beverly (GH #6, #7, #10, #17, #22, #24, #25, #26). This includes
    support for creating and editing users and manage user passwords.

    Gabor Szabo (GH #11, #16, #18).

    Evan Brown (GH #20, #32).

    Jason Lewis (Unix provider problem, typo fix).

    Yanick Champoux (typo fix).

LICENSE AND COPYRIGHT

    Copyright 2012-16 David Precious. Copyright 2017-19 Stefan Hornburg
    (Racke).

    This program is free software; you can redistribute it and/or modify it
    under the terms of either: the GNU General Public License as published
    by the Free Software Foundation; or the Artistic License.

    See http://dev.perl.org/licenses/ for more information.