3 Catalyst::Manual::Tutorial::Authorization - Catalyst Tutorial - Part 6: Authorization
8 This is B<Part 6 of 10> for the Catalyst tutorial.
10 L<Tutorial Overview|Catalyst::Manual::Tutorial>
16 L<Introduction|Catalyst::Manual::Tutorial::Intro>
20 L<Catalyst Basics|Catalyst::Manual::Tutorial::CatalystBasics>
24 L<More Catalyst Basics|Catalyst::Manual::Tutorial::MoreCatalystBasics>
28 L<Basic CRUD|Catalyst::Manual::Tutorial::BasicCRUD>
32 L<Authentication|Catalyst::Manual::Tutorial::Authentication>
40 L<Debugging|Catalyst::Manual::Tutorial::Debugging>
44 L<Testing|Catalyst::Manual::Tutorial::Testing>
48 L<Advanced CRUD|Catalyst::Manual::Tutorial::AdvancedCRUD>
52 L<Appendices|Catalyst::Manual::Tutorial::Appendices>
59 This part of the tutorial adds role-based authorization to the existing
60 authentication implemented in Part 4. It provides simple examples of
61 how to use roles in both TT templates and controller actions. The first
62 half looks at manually configured authorization. The second half looks
63 at how the ACL authorization plugin can simplify your code.
65 You can checkout the source code for this example from the catalyst
66 subversion repository as per the instructions in
67 L<Catalyst::Manual::Tutorial::Intro>
69 =head1 BASIC AUTHORIZATION
71 In this section you learn how to manually configure authorization.
73 =head2 Update Plugins to Include Support for Authorization
75 Edit C<lib/MyApp.pm> and add C<Authorization::Roles> to the list:
88 Session::Store::FastMmap
89 Session::State::Cookie
93 =head2 Add Config Information for Authorization
95 Edit C<myapp.yml> and update it to match the following (the
96 C<role_relation> and C<role_field> definitions are new):
105 # Note this first definition would be the same as setting
106 # __PACKAGE__->config->{authentication}->{realms}->{dbic}
107 # ->{credential} = 'Password' in lib/MyApp.pm
109 # Specify that we are going to do password-based auth
111 # This is the name of the field in the users table with the
112 # password stored in it
113 password_field password
114 # We are using an unencrypted password now
118 # Use DBIC to retrieve username, password & role information
120 # This is the model object created by Catalyst::Model::DBIC
121 # from your schema (you created 'MyAppDB::User' but as the
122 # Catalyst startup debug messages show, it was loaded as
123 # 'MyApp::Model::MyAppDB::Users').
124 # NOTE: Omit 'MyApp::Model' here just as you would when using
125 # '$c->model("MyAppDB::Users)'
126 user_class MyAppDB::Users
127 # This is the name of the field in your 'users' table that
128 # contains the user's name
130 # This is the name of a many_to_many relation in the users
131 # object that points to the roles for that user
133 # This is the name of field in the roles table that contains
134 # the role information
142 =head2 Add Role-Specific Logic to the "Book List" Template
144 Open C<root/src/books/list.tt2> in your editor and add the following
145 lines to the bottom of the file:
147 <p>Hello [% Catalyst.user.username %], you have the following roles:</p>
150 [% # Dump list of roles -%]
151 [% FOR role = Catalyst.user.roles %]<li>[% role %]</li>[% END %]
155 [% # Add some simple role-specific logic to template %]
156 [% # Use $c->check_user_roles() to check authz -%]
157 [% IF Catalyst.check_user_roles('user') %]
158 [% # Give normal users a link for 'logout' %]
159 <a href="[% Catalyst.uri_for('/logout') %]">Logout</a>
162 [% # Can also use $c->user->check_roles() to check authz -%]
163 [% IF Catalyst.check_user_roles('admin') %]
164 [% # Give admin users a link for 'create' %]
165 <a href="[% Catalyst.uri_for('form_create') %]">Create</a>
169 This code displays a different combination of links depending on the
170 roles assigned to the user.
172 =head2 Limit C<Books::add> to C<admin> Users
174 C<IF> statements in TT templates simply control the output that is sent
175 to the user's browser; it provides no real enforcement (if users know or
176 guess the appropriate URLs, they are still perfectly free to hit any
177 action within your application). We need to enhance the controller
178 logic to wrap restricted actions with role-validation logic.
180 For example, we might want to restrict the "formless create" action to
181 admin-level users by editing C<lib/MyApp/Controller/Books.pm> and
182 updating C<url_create> to match the following code:
186 Create a book with the supplied title and rating,
187 with manual authorization
191 sub url_create : Local {
192 # In addition to self & context, get the title, rating & author_id args
193 # from the URL. Note that Catalyst automatically puts extra information
194 # after the "/<controller_name>/<action_name/" into @_
195 my ($self, $c, $title, $rating, $author_id) = @_;
197 # Check the user's roles
198 if ($c->check_user_roles('admin')) {
199 # Call create() on the book model object. Pass the table
200 # columns/field values we want to set as hash values
201 my $book = $c->model('MyAppDB::Books')->create({
206 # Add a record to the join table for this book, mapping to
208 $book->add_to_book_authors({author_id => $author_id});
209 # Note: Above is a shortcut for this:
210 # $book->create_related('book_authors', {author_id => $author_id});
212 # Assign the Book object to the stash for display in the view
213 $c->stash->{book} = $book;
215 # This is a hack to disable XSUB processing in Data::Dumper
216 # (it's used in the view). This is a work-around for a bug in
217 # the interaction of some versions or Perl, Data::Dumper & DBIC.
218 # You won't need this if you aren't using Data::Dumper (or if
219 # you are running DBIC 0.06001 or greater), but adding it doesn't
220 # hurt anything either.
221 $Data::Dumper::Useperl = 1;
223 # Set the TT template to use
224 $c->stash->{template} = 'books/create_done.tt2';
226 # Provide very simple feedback to the user
227 $c->response->body('Unauthorized!');
232 To add authorization, we simply wrap the main code of this method in an
233 C<if> statement that calls C<check_user_roles>. If the user does not
234 have the appropriate permissions, they receive an "Unauthorized!"
235 message. Note that we intentionally chose to display the message this
236 way to demonstrate that TT templates will not be used if the response
237 body has already been set. In reality you would probably want to use a
238 technique that maintains the visual continuity of your template layout
239 (for example, using the "status" or "error" message feature added in
242 B<TIP>: If you want to keep your existing C<url_create> method, you can
243 create a new copy and comment out the original by making it look like a
244 Pod comment. For example, put something like C<=begin> before C<sub add
245 : Local {> and C<=end> after the closing C<}>.
247 =head2 Try Out Authentication And Authorization
249 Press C<Ctrl-C> to kill the previous server instance (if it's still
250 running) and restart it:
252 $ script/myapp_server.pl
254 Now trying going to L<http://localhost:3000/books/list> and you should
255 be taken to the login page (you might have to C<Shift+Reload> your
256 browser and/or click the "Logout" link on the book list page). Try
257 logging in with both C<test01> and C<test02> (both use a password
258 of C<mypass>) and notice how the roles information updates at the
259 bottom of the "Book List" page. Also try the C<Logout> link on the
262 Now the "url_create" URL will work if you are already logged in as user
263 C<test01>, but receive an authorization failure if you are logged in as
266 http://localhost:3000/books/url_create/test/1/6
268 while logged in as each user. Use one of the 'Logout' links (or go to
269 L<http://localhost:3000/logout> in you browser directly) when you are
273 =head1 ENABLE ACL-BASED AUTHORIZATION
275 This section takes a brief look at how the
276 L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL>
277 plugin can automate much of the work required to perform role-based
278 authorization in a Catalyst application.
280 =head2 Add the C<Catalyst::Plugin::Authorization::ACL> Plugin
282 Open C<lib/MyApp.pm> in your editor and add the following plugin to the
283 C<use Catalyst> statement:
287 Note that the remaining C<use Catalyst> plugins from earlier sections
288 are not shown here, but they should still be included.
290 =head2 Add ACL Rules to the Application Class
292 Open C<lib/MyApp.pm> in your editor and add the following B<BELOW> the
293 C<__PACKAGE__-E<gt>setup;> statement:
295 # Authorization::ACL Rules
296 __PACKAGE__->deny_access_unless(
297 "/books/form_create",
300 __PACKAGE__->deny_access_unless(
301 "/books/form_create_do",
304 __PACKAGE__->deny_access_unless(
309 Each of the three statements above comprises an ACL plugin "rule". The
310 first two rules only allow admin-level users to create new books using
311 the form (both the form itself and the data submission logic are
312 protected). The third statement allows both users and admins to delete
313 books. The C</books/url_create> action will continue to be protected by
314 the "manually configured" authorization created earlier in this part of
317 The ACL plugin permits you to apply allow/deny logic in a variety of
318 ways. The following provides a basic overview of the capabilities:
324 The ACL plugin only operates on the Catalyst "private namespace". You
325 are using the private namespace when you use C<Local> actions. C<Path>,
326 C<Regex>, and C<Global> allow you to specify actions where the path and
327 the namespace differ -- the ACL plugin will not work in these cases.
331 Each rule is expressed in a separate
332 C<__PACKAGE__-E<gt>deny_access_unless()> or
333 C<__PACKAGE__-E<gt>allow_access_if()> line (there are several other
334 methods that can be used for more complex policies, see the C<METHODS>
336 L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL>
337 documentation for more details).
341 Each rule can contain multiple roles but only a single path.
345 The rules are tried in order (with the "most specific" rules tested
346 first), and processing stops at the first "match" where an allow or deny
347 is specified. Rules "fall through" if there is not a "match" (where a
348 "match" means the user has the specified role). If a "match" is found,
349 then processing stops there and the appropriate allow/deny action is
354 If none of the rules match, then access is allowed.
358 The rules currently need to be specific in the application class
359 C<lib\MyApp.pm> B<after> the C<__PACKAGE__-E<gt>setup;> line.
363 =head2 Add a Method to Handle Access Violations
366 L<Catalyst::Plugin::Authorization::ACL|Catalyst::Plugin::Authorization::ACL>
367 throws an exception when authorization fails. This will take the user
368 to the Catalyst debug screen, or a "Please come back later" message if
369 you are not using the C<-Debug> flag. This step uses the
370 C<access_denied> method in order to provide more appropriate feedback to
373 Open C<lib/MyApp/Controller/Books.pm> in your editor and add the
378 Handle Catalyst::Plugin::Authorization::ACL access denied exceptions
382 sub access_denied : Private {
385 # Set the error message
386 $c->stash->{error_msg} = 'Unauthorized!';
392 Then run the Catalyst development server script:
394 $ script/myapp_server.pl
396 Log in as C<test02>. Once at the book list, click the "Create" link
397 to try the C<form_create> action. You should receive a red
398 "Unauthorized!" error message at the top of the list. (Note that in
399 the example code the "Create" link code in C<root/src/books/list.tt2>
400 is inside an C<IF> statement that only displays the list to
401 admin-level users.) If you log in as C<test01> you should be able to
402 view the C<form_create> form and add a new book.
404 When you are done, use one of the 'Logout' links (or go to the
405 L<http://localhost:3000/logout> URL directly) when you are done.
410 Kennedy Clark, C<hkclark@gmail.com>
412 Please report any errors, issues or suggestions to the author. The
413 most recent version of the Catalyst Tutorial can be found at
414 L<http://dev.catalyst.perl.org/repos/Catalyst/trunk/Catalyst-Manual/lib/Catalyst/Manual/Tutorial/>.
416 Copyright 2006, Kennedy Clark, under Creative Commons License
417 (L<http://creativecommons.org/licenses/by-nc-sa/2.5/>).