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1= Trac and mod_wsgi
2
3[https://github.com/GrahamDumpleton/mod_wsgi mod_wsgi] is an Apache module for running WSGI-compatible Python applications directly on top of the Apache webserver. The mod_wsgi adapter is written completely in C and provides very good performance.
4
5[[PageOutline(2-3,Overview,inline)]]
6
7== The `trac.wsgi` script
8
9Trac can be run on top of mod_wsgi with the help of an application script, which is just a Python file saved with a `.wsgi` extension. 
10
11A robust and generic version of this file can be created using the `trac-admin <env> deploy <dir>` command which automatically substitutes the required paths, see TracInstall#cgi-bin. The script should be sufficient for most installations and users not wanting more information can proceed to [#Mappingrequeststothescript configuring Apache].
12
13If you are using Trac with multiple projects, you can specify their common parent directory using the `TRAC_ENV_PARENT_DIR` in trac.wsgi:
14{{{#!python
15def application(environ, start_request):
16    # Add this to config when you have multiple projects                                             
17    environ.setdefault('trac.env_parent_dir', '/usr/share/trac/projects') 
18    ..
19}}}
20
21=== A very basic script
22In its simplest form, the script could be:
23
24{{{#!python
25import os
26
27os.environ['TRAC_ENV'] = '/usr/local/trac/mysite'
28os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
29
30import trac.web.main
31application = trac.web.main.dispatch_request
32}}}
33
34The `TRAC_ENV` variable should naturally be the directory for your Trac environment, and the `PYTHON_EGG_CACHE` should be a directory where Python can temporarily extract Python eggs. If you have several Trac environments in a directory, you can also use `TRAC_ENV_PARENT_DIR` instead of `TRAC_ENV`.
35
36On Windows:
37 - If run under the user's session, the Python Egg cache can be found in `%AppData%\Roaming`, for example:
38{{{#!python
39os.environ['PYTHON_EGG_CACHE'] = r'C:\Users\Administrator\AppData\Roaming\Python-Eggs'
40}}}
41 - If run under a Window service, you should create a directory for Python Egg cache:
42{{{#!python
43os.environ['PYTHON_EGG_CACHE'] = r'C:\Trac-Python-Eggs'
44}}}
45
46=== A more elaborate script
47
48If you are using multiple `.wsgi` files (for example one per Trac environment) you must ''not'' use `os.environ['TRAC_ENV']` to set the path to the Trac environment. Using this method may lead to Trac delivering the content of another Trac environment, as the variable may be filled with the path of a previously viewed Trac environment. 
49
50To solve this problem, use the following `.wsgi` file instead:
51{{{#!python
52import os
53
54os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
55
56import trac.web.main
57def application(environ, start_response):
58  environ['trac.env_path'] = '/usr/local/trac/mysite' 
59  return trac.web.main.dispatch_request(environ, start_response)
60}}}
61
62For clarity, you should give this file a `.wsgi` extension. You should probably put the file in its own directory, since you will expose it to Apache. 
63
64If you have installed Trac and Python eggs in a path different from the standard one, you should add that path by adding the following code at the top of the wsgi script:
65
66{{{#!python
67import site
68site.addsitedir('/usr/local/trac/lib/python2.4/site-packages')
69}}}
70
71Change it according to the path you installed the Trac libs at.
72
73== Mapping requests to the script
74
75After preparing your .wsgi script, add the following to your Apache configuration file, typically `httpd.conf`:
76
77{{{#!apache
78WSGIScriptAlias /trac /usr/local/trac/mysite/apache/mysite.wsgi
79
80<Directory /usr/local/trac/mysite/apache>
81    WSGIApplicationGroup %{GLOBAL}
82    Order deny,allow
83    Allow from all
84</Directory>
85}}}
86
87Here, the script is in a subdirectory of the Trac environment.
88
89If you followed the directions [TracInstall#cgi-bin Generating the Trac cgi-bin directory], your Apache configuration file should look like following:
90
91{{{#!apache
92WSGIScriptAlias /trac /usr/share/trac/cgi-bin/trac.wsgi
93
94<Directory /usr/share/trac/cgi-bin>
95    WSGIApplicationGroup %{GLOBAL}
96    Order deny,allow
97    Allow from all
98</Directory>
99}}}
100
101In order to let Apache run the script, access to the directory in which the script resides is opened up to all of Apache. Additionally, the `WSGIApplicationGroup` directive ensures that Trac is always run in the first Python interpreter created by mod_wsgi. This is necessary because the Subversion Python bindings, which are used by Trac, don't always work in other sub-interpreters and may cause requests to hang or cause Apache to crash. After adding this configuration, restart Apache, and then it should work.
102
103To test the setup of Apache, mod_wsgi and Python itself (ie. without involving Trac and dependencies), this simple wsgi application can be used to make sure that requests gets served (use as only content in your `.wsgi` script):
104
105{{{#!python
106def application(environ, start_response):
107        start_response('200 OK',[('Content-type','text/html')])
108        return ['<html><body>Hello World!</body></html>']
109}}}
110
111For more information about using the mod_wsgi specific directives, see the [http://code.google.com/p/modwsgi/wiki/ mod_wsgi's wiki] and more specifically the [http://code.google.com/p/modwsgi/wiki/IntegrationWithTrac IntegrationWithTrac] page.
112
113== Configuring Authentication
114
115The following sections describe different methods for setting up authentication. See also [http://httpd.apache.org/docs/2.2/howto/auth.html Authentication, Authorization and Access Control] in the Apache guide.
116
117=== Using Basic Authentication
118
119The simplest way to enable authentication with Apache is to create a password file. Use the `htpasswd` program as follows:
120{{{#!sh
121$ htpasswd -c /somewhere/trac.htpasswd admin
122New password: <type password>
123Re-type new password: <type password again>
124Adding password for user admin
125}}}
126
127After the first user, you don't need the "-c" option anymore:
128{{{#!sh
129$ htpasswd /somewhere/trac.htpasswd john
130New password: <type password>
131Re-type new password: <type password again>
132Adding password for user john
133}}}
134
135  ''See the man page for `htpasswd` for full documentation.''
136
137After you've created the users, you can set their permissions using TracPermissions.
138
139Now, you need to enable authentication against the password file in the Apache configuration:
140{{{#!apache
141<Location "/trac/login">
142  AuthType Basic
143  AuthName "Trac"
144  AuthUserFile /somewhere/trac.htpasswd
145  Require valid-user
146</Location>
147}}}
148
149If you are hosting multiple projects, you can use the same password file for all of them:
150{{{#!apache
151<LocationMatch "/trac/[^/]+/login">
152  AuthType Basic
153  AuthName "Trac"
154  AuthUserFile /somewhere/trac.htpasswd
155  Require valid-user
156</LocationMatch>
157}}}
158Note that neither a file nor a directory named 'login' needs to exist.[[BR]]
159See also the [http://httpd.apache.org/docs/2.2/mod/mod_auth_basic.html mod_auth_basic] documentation.
160
161=== Using Digest Authentication
162
163For better security, it is recommended that you either enable SSL or at least use the digest authentication scheme instead of Basic. 
164
165You have to create your `.htpasswd` file with the `htdigest` command instead of `htpasswd`, as follows:
166{{{#!sh
167$ htdigest -c /somewhere/trac.htpasswd trac admin
168}}}
169
170The "trac" parameter above is the "realm", and will have to be reused in the Apache configuration in the !AuthName directive:
171
172{{{#!apache
173<Location "/trac/login">
174  AuthType Digest
175  AuthName "trac"
176  AuthDigestDomain /trac
177  AuthUserFile /somewhere/trac.htpasswd
178  Require valid-user
179</Location>
180}}}
181
182For multiple environments, you can use the same `LocationMatch` as described with the previous method.
183
184'''Note: `Location` cannot be used inside .htaccess files, but must instead live within the main httpd.conf file. If you are on a shared server, you therefore will not be able to provide this level of granularity. '''
185
186Don't forget to activate the mod_auth_digest. For example, on a Debian 4.0r1 (etch) system:
187{{{#!apache
188  LoadModule auth_digest_module /usr/lib/apache2/modules/mod_auth_digest.so
189}}}
190
191See also the [http://httpd.apache.org/docs/2.2/mod/mod_auth_digest.html mod_auth_digest] documentation.
192
193=== Using LDAP Authentication
194
195Configuration for [http://httpd.apache.org/docs/2.2/mod/mod_ldap.html mod_ldap] authentication in Apache is more involved (httpd 2.2.x and OpenLDAP: slapd 2.3.19).
196
1971. You need to load the following modules in Apache httpd.conf:
198{{{#!apache
199  LoadModule ldap_module modules/mod_ldap.so
200  LoadModule authnz_ldap_module modules/mod_authnz_ldap.so
201}}}
2021. Your httpd.conf also needs to look something like:
203{{{#!apache
204<Location /trac/>
205  # (if you're using it, mod_python specific settings go here)
206  Order deny,allow
207  Deny from all
208  Allow from 192.168.11.0/24
209  AuthType Basic
210  AuthName "Trac"
211  AuthBasicProvider "ldap"
212  AuthLDAPURL "ldap://127.0.0.1/dc=example,dc=co,dc=ke?uid?sub?(objectClass=inetOrgPerson)"
213  authzldapauthoritative Off
214  Require valid-user
215</Location>
216}}}
2171. You can use the LDAP interface as a way to authenticate to a Microsoft Active Directory. Use the following as your LDAP URL:
218{{{#!apache
219  AuthLDAPURL "ldap://directory.example.com:3268/DC=example,DC=com?sAMAccountName?sub?(objectClass=user)"
220}}}
221 You will also need to provide an account for Apache to use when checking credentials. As this password will be listed in plaintext in the config, you need to use an account specifically for this task:
222{{{#!apache
223  AuthLDAPBindDN ldap-auth-user@example.com
224  AuthLDAPBindPassword "password"
225}}}
226 The whole section looks like:
227{{{#!apache
228<Location /trac/>
229  # (if you're using it, mod_python specific settings go here)
230  Order deny,allow
231  Deny from all
232  Allow from 192.168.11.0/24
233  AuthType Basic
234  AuthName "Trac"
235  AuthBasicProvider "ldap"
236  AuthLDAPURL "ldap://adserver.company.com:3268/DC=company,DC=com?sAMAccountName?sub?(objectClass=user)"
237  AuthLDAPBindDN       ldap-auth-user@company.com
238  AuthLDAPBindPassword "the_password"
239  authzldapauthoritative Off
240  # require valid-user
241  Require ldap-group CN=Trac Users,CN=Users,DC=company,DC=com
242</Location>
243}}}
244
245Note 1: This is the case where the LDAP search will get around the multiple OUs, conecting to the Global Catalog Server portion of AD. Note the port is 3268, not the normal LDAP 389. The GCS is basically a "flattened" tree which allows searching for a user without knowing to which OU they belong.
246
247Note 2: You can also require the user be a member of a certain LDAP group, instead of just having a valid login:
248{{{#!apache
249  Require ldap-group CN=Trac Users,CN=Users,DC=example,DC=com
250}}}
251
252See also:
253 - [http://httpd.apache.org/docs/2.2/mod/mod_authnz_ldap.html mod_authnz_ldap], documentation for mod_authnz_ldap.   
254 - [http://httpd.apache.org/docs/2.2/mod/mod_ldap.html mod_ldap], documentation for mod_ldap, which provides connection pooling and a shared cache.
255 - [http://trac-hacks.org/wiki/LdapPlugin TracHacks:LdapPlugin] for storing TracPermissions in LDAP.
256
257=== Using SSPI Authentication
258
259If you are using Apache on Windows, you can use mod_auth_sspi to provide single-sign-on. Download the module from the !SourceForge [http://sourceforge.net/projects/mod-auth-sspi/ mod-auth-sspi project] and then add the following to your !VirtualHost:
260{{{#!apache
261<Location /trac/login>
262  AuthType SSPI
263  AuthName "Trac Login"
264  SSPIAuth On
265  SSPIAuthoritative On
266  SSPIDomain MyLocalDomain
267  SSPIOfferBasic On
268  SSPIOmitDomain Off
269  SSPIBasicPreferred On
270  Require valid-user
271</Location>
272}}}
273
274Using the above, usernames in Trac will be of the form `DOMAIN\username`, so you may have to re-add permissions and such. If you do not want the domain to be part of the username, set `SSPIOmitDomain On` instead.
275
276Some common problems with SSPI authentication: [trac:#1055], [trac:#1168] and [trac:#3338].
277
278See also [trac:TracOnWindows/Advanced].
279
280=== Using Apache authentication with the Account Manager plugin's Login form ===
281
282To begin with, see the basic instructions for using the Account Manager plugin's [http://trac-hacks.org/wiki/AccountManagerPlugin/Modules#LoginModule Login module] and its [http://trac-hacks.org/wiki/AccountManagerPlugin/AuthStores#HttpAuthStore HttpAuthStore authentication module].
283
284'''Note:''' If is difficult to get !HttpAuthStore to work with WSGI when using any Account Manager version prior to acct_mgr-0.4. Upgrading is recommended.
285
286Here is an example (from the !HttpAuthStore link) using acct_mgr-0.4 for hosting a single project:
287{{{#!ini
288[components]
289; be sure to enable the component
290acct_mgr.http.HttpAuthStore = enabled
291
292[account-manager]
293; configure the plugin to use a page that is secured with http authentication
294authentication_url = /authFile
295password_store = HttpAuthStore
296}}}
297This will generally be matched with an Apache config like:
298{{{#!apache
299<Location /authFile>
300   HTTP authentication configuration
301   Require valid-user
302</Location>
303}}}
304Note that '''authFile''' need not exist (unless you are using Account Manager older than 0.4). See the !HttpAuthStore link above for examples where multiple Trac projects are hosted on a server.
305
306=== Example: Apache/mod_wsgi with Basic Authentication, Trac being at the root of a virtual host
307
308Per the mod_wsgi documentation linked to above, here is an example Apache configuration that:
309 - serves the Trac instance from a virtualhost subdomain
310 - uses Apache basic authentication for Trac authentication.
311
312If you want your Trac to be served from e.g. !http://trac.my-proj.my-site.org, then from the folder e.g. `/home/trac-for-my-proj`, if you used the command `trac-admin the-env initenv` to create a folder `the-env`, and you used `trac-admin the-env deploy the-deploy` to create a folder `the-deploy`, then first:
313
314Create the htpasswd file:
315{{{#!sh
316cd /home/trac-for-my-proj/the-env
317htpasswd -c htpasswd firstuser
318### and add more users to it as needed:
319htpasswd htpasswd seconduser
320}}}
321Keep the file above your document root for security reasons.
322
323Create this file e.g. (ubuntu) `/etc/apache2/sites-enabled/trac.my-proj.my-site.org.conf` with the following content:
324
325{{{#!apache
326<Directory /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi>
327  WSGIApplicationGroup %{GLOBAL}
328  Order deny,allow
329  Allow from all
330</Directory>
331
332<VirtualHost *:80>
333  ServerName trac.my-proj.my-site.org
334  DocumentRoot /home/trac-for-my-proj/the-env/htdocs/
335  WSGIScriptAlias / /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi
336  <Location '/'>
337    AuthType Basic
338    AuthName "Trac"
339    AuthUserFile /home/trac-for-my-proj/the-env/htpasswd
340    Require valid-user
341  </Location>
342</VirtualHost>
343
344}}}
345
346Note: for subdomains to work you would probably also need to alter `/etc/hosts` and add A-Records to your host's DNS.
347
348== Troubleshooting
349
350=== Use a recent version
351
352Please use either version 1.6, 2.4 or later of `mod_wsgi`. Versions prior to 2.4 in the 2.X branch have problems with some Apache configurations that use WSGI file wrapper extension. This extension is used in Trac to serve up attachments and static media files such as style sheets. If you are affected by this problem, attachments will appear to be empty and formatting of HTML pages will appear not to work due to style sheet files not loading properly. Another frequent symptom is that binary attachment downloads are truncated. See mod_wsgi tickets [http://code.google.com/p/modwsgi/issues/detail?id=100 #100] and [http://code.google.com/p/modwsgi/issues/detail?id=132 #132].
353
354''Note: using mod_wsgi 2.5 and Python 2.6.1 gave an Internal Server Error on my system (Apache 2.2.11 and Trac 0.11.2.1). Upgrading to Python 2.6.2 (as suggested [http://www.mail-archive.com/modwsgi@googlegroups.com/msg01917.html here]) solved this for me[[BR]]-- Graham Shanks''
355
356If you plan to use `mod_wsgi` in embedded mode on Windows or with the MPM worker on Linux, then you will need version 3.4 or greater. See [trac:#10675] for details.
357
358=== Getting Trac to work nicely with SSPI and 'Require Group'
359
360If you have set Trac up on Apache, Win32 and configured SSPI, but added a 'Require group' option to your apache configuration, then the SSPIOmitDomain option is probably not working. If it is not working, your usernames in Trac probably look like 'DOMAIN\user' rather than 'user'.
361
362This WSGI script 'fixes' that:
363{{{#!python
364import os
365import trac.web.main
366
367os.environ['TRAC_ENV'] = '/usr/local/trac/mysite'
368os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
369
370def application(environ, start_response):
371    if "\\" in environ['REMOTE_USER']:
372        environ['REMOTE_USER'] = environ['REMOTE_USER'].split("\\", 1)[1]
373    return trac.web.main.dispatch_request(environ, start_response)
374}}}
375
376=== Trac with PostgreSQL
377
378When using the mod_wsgi adapter with multiple Trac instances and PostgreSQL (or MySQL?) as the database, the server ''may'' create a lot of open database connections and thus PostgreSQL processes.
379
380A somewhat brutal workaround is to disable connection pooling in Trac. This is done by setting `poolable = False` in `trac.db.postgres_backend` on the `PostgreSQLConnection` class.
381
382But it is not necessary to edit the source of Trac. The following lines in `trac.wsgi` will also work:
383
384{{{#!python
385import trac.db.postgres_backend
386trac.db.postgres_backend.PostgreSQLConnection.poolable = False
387}}}
388
389or
390
391{{{#!python
392import trac.db.mysql_backend
393trac.db.mysql_backend.MySQLConnection.poolable = False
394}}}
395
396Now Trac drops the connection after serving a page and the connection count on the database will be kept low.
397
398//This is not a recommended approach though. See also the notes at the bottom of the [http://code.google.com/p/modwsgi/wiki/IntegrationWithTrac mod_wsgi's IntegrationWithTrac] wiki page.//
399
400=== Other resources
401
402For more troubleshooting tips, see also the [TracModPython#Troubleshooting mod_python troubleshooting] section, as most Apache-related issues are quite similar, plus discussion of potential [http://code.google.com/p/modwsgi/wiki/ApplicationIssues application issues] when using mod_wsgi. The wsgi page also has a [http://code.google.com/p/modwsgi/wiki/IntegrationWithTrac Integration With Trac] document.
403
404----
405See also: TracGuide, TracInstall, [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]
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