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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 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
22
23In its simplest form, the script could be:
24
25{{{#!python
26import os
27
28os.environ['TRAC_ENV'] = '/usr/local/trac/mysite'
29os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
30
31import trac.web.main
32application = trac.web.main.dispatch_request
33}}}
34
35The `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`.
36
37On Windows:
38 - If run under the user's session, the Python Egg cache can be found in `%AppData%\Roaming`, for example:
39{{{#!python
40os.environ['PYTHON_EGG_CACHE'] = r'C:\Users\Administrator\AppData\Roaming\Python-Eggs'
41}}}
42 - If run under a Window service, you should create a directory for Python Egg cache:
43{{{#!python
44os.environ['PYTHON_EGG_CACHE'] = r'C:\Trac-Python-Eggs'
45}}}
46
47=== A more elaborate script
48
49If 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. 
50
51To solve this problem, use the following `.wsgi` file instead:
52{{{#!python
53import os
54
55os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
56
57import trac.web.main
58def application(environ, start_response):
59  environ['trac.env_path'] = '/usr/local/trac/mysite' 
60  return trac.web.main.dispatch_request(environ, start_response)
61}}}
62
63For 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. 
64
65If 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:
66
67{{{#!python
68import site
69site.addsitedir('/usr/local/trac/lib/python2.4/site-packages')
70}}}
71
72Change it according to the path you installed the Trac libs at.
73
74== Mapping requests to the script
75
76After preparing your .wsgi script, add the following to your Apache configuration file, typically `httpd.conf`:
77
78{{{#!apache
79WSGIScriptAlias /trac /usr/local/trac/mysite/apache/mysite.wsgi
80
81<Directory /usr/local/trac/mysite/apache>
82    WSGIApplicationGroup %{GLOBAL}
83    # For Apache 2.2
84    <IfModule !mod_authz_core.c>
85        Order deny,allow
86        Allow from all
87    </IfModule>
88    # For Apache 2.4
89    <IfModule mod_authz_core.c>
90        Require all granted
91    </IfModule>
92</Directory>
93}}}
94
95Here, the script is in a subdirectory of the Trac environment.
96
97If you followed the directions [TracInstall#cgi-bin Generating the Trac cgi-bin directory], your Apache configuration file should look like following:
98
99{{{#!apache
100WSGIScriptAlias /trac /usr/share/trac/cgi-bin/trac.wsgi
101
102<Directory /usr/share/trac/cgi-bin>
103    WSGIApplicationGroup %{GLOBAL}
104    # For Apache 2.2
105    <IfModule !mod_authz_core.c>
106        Order deny,allow
107        Allow from all
108    </IfModule>
109    # For Apache 2.4
110    <IfModule mod_authz_core.c>
111        Require all granted
112    </IfModule>
113</Directory>
114}}}
115
116In 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.
117
118To 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):
119
120{{{#!python
121def application(environ, start_response):
122        start_response('200 OK',[('Content-type','text/html')])
123        return ['<html><body>Hello World!</body></html>']
124}}}
125
126For more information about using the mod_wsgi specific directives, see the [https://code.google.com/archive/p/modwsgi/wikis mod_wsgi's wiki] and more specifically the [https://code.google.com/archive/p/modwsgi/wikis/IntegrationWithTrac.wiki IntegrationWithTrac] page.
127
128== Configuring Authentication
129
130The following sections describe different methods for setting up authentication. See also [http://httpd.apache.org/docs/2.4/howto/auth.html Authentication, Authorization and Access Control] in the Apache guide.
131
132=== Using Basic Authentication
133
134The simplest way to enable authentication with Apache is to create a password file. Use the `htpasswd` program as follows:
135{{{#!sh
136$ htpasswd -c /somewhere/trac.htpasswd admin
137New password: <type password>
138Re-type new password: <type password again>
139Adding password for user admin
140}}}
141
142After the first user, you don't need the "-c" option anymore:
143{{{#!sh
144$ htpasswd /somewhere/trac.htpasswd john
145New password: <type password>
146Re-type new password: <type password again>
147Adding password for user john
148}}}
149
150See the man page for `htpasswd` for full documentation.
151
152After you've created the users, you can set their permissions using TracPermissions.
153
154Now, you need to enable authentication against the password file in the Apache configuration:
155{{{#!apache
156<Location "/trac/login">
157  AuthType Basic
158  AuthName "Trac"
159  AuthUserFile /somewhere/trac.htpasswd
160  Require valid-user
161</Location>
162}}}
163
164If you are hosting multiple projects, you can use the same password file for all of them:
165{{{#!apache
166<LocationMatch "/trac/[^/]+/login">
167  AuthType Basic
168  AuthName "Trac"
169  AuthUserFile /somewhere/trac.htpasswd
170  Require valid-user
171</LocationMatch>
172}}}
173
174Note that neither a file nor a directory named 'login' needs to exist. See also the [https://httpd.apache.org/docs/2.4/mod/mod_auth_basic.html mod_auth_basic] documentation.
175
176=== Using Digest Authentication
177
178For better security, it is recommended that you either enable SSL or at least use the "digest" authentication scheme instead of "Basic".
179
180You have to create your `.htpasswd` file with the `htdigest` command instead of `htpasswd`, as follows:
181{{{#!sh
182$ htdigest -c /somewhere/trac.htpasswd trac admin
183}}}
184
185The "trac" parameter above is the "realm", and will have to be reused in the Apache configuration in the !AuthName directive:
186
187{{{#!apache
188<Location "/trac/login">
189  AuthType Digest
190  AuthName "trac"
191  AuthDigestDomain /trac
192  AuthUserFile /somewhere/trac.htpasswd
193  Require valid-user
194</Location>
195}}}
196
197For multiple environments, you can use the same `LocationMatch` as described with the previous method.
198
199'''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.
200
201Don't forget to activate the mod_auth_digest. For example, on a Debian 4.0r1 (etch) system:
202{{{#!apache
203  LoadModule auth_digest_module /usr/lib/apache2/modules/mod_auth_digest.so
204}}}
205
206See also the [https://httpd.apache.org/docs/2.4/mod/mod_auth_basic.html mod_auth_digest] documentation.
207
208=== Using LDAP Authentication
209
210Configuration for [https://httpd.apache.org/docs/2.4/mod/mod_ldap.html mod_ldap] authentication in Apache is more involved (httpd 2.2+ and OpenLDAP: slapd 2.3.19).
211
2121. You need to load the following modules in Apache httpd.conf:
213{{{#!apache
214  LoadModule ldap_module modules/mod_ldap.so
215  LoadModule authnz_ldap_module modules/mod_authnz_ldap.so
216}}}
2171. Your httpd.conf also needs to look something like:
218{{{#!apache
219<Location /trac/>
220  # (if you're using it, mod_python specific settings go here)
221  Order deny,allow
222  Deny from all
223  Allow from 192.168.11.0/24
224  AuthType Basic
225  AuthName "Trac"
226  AuthBasicProvider "ldap"
227  AuthLDAPURL "ldap://127.0.0.1/dc=example,dc=co,dc=ke?uid?sub?(objectClass=inetOrgPerson)"
228  authzldapauthoritative Off
229  Require valid-user
230</Location>
231}}}
2321. You can use the LDAP interface as a way to authenticate to a Microsoft Active Directory. Use the following as your LDAP URL:
233{{{#!apache
234  AuthLDAPURL "ldap://directory.example.com:3268/DC=example,DC=com?sAMAccountName?sub?(objectClass=user)"
235}}}
236 You will also need to provide an account for Apache to use when checking credentials. As this password will be listed in plain text in the configuration, you need to use an account specifically for this task:
237{{{#!apache
238  AuthLDAPBindDN ldap-auth-user@example.com
239  AuthLDAPBindPassword "password"
240}}}
241 The whole section looks like:
242{{{#!apache
243<Location /trac/>
244  # (if you're using it, mod_python specific settings go here)
245  Order deny,allow
246  Deny from all
247  Allow from 192.168.11.0/24
248  AuthType Basic
249  AuthName "Trac"
250  AuthBasicProvider "ldap"
251  AuthLDAPURL "ldap://adserver.company.com:3268/DC=company,DC=com?sAMAccountName?sub?(objectClass=user)"
252  AuthLDAPBindDN       ldap-auth-user@company.com
253  AuthLDAPBindPassword "the_password"
254  authzldapauthoritative Off
255  # require valid-user
256  Require ldap-group CN=Trac Users,CN=Users,DC=company,DC=com
257</Location>
258}}}
259
260Note 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.
261
262Note 2: You can also require the user be a member of a certain LDAP group, instead of just having a valid login:
263{{{#!apache
264  Require ldap-group CN=Trac Users,CN=Users,DC=example,DC=com
265}}}
266
267See also:
268 - [https://httpd.apache.org/docs/2.4/mod/mod_authnz_ldap.html mod_authnz_ldap], documentation for mod_authnz_ldap.   
269 - [https://httpd.apache.org/docs/2.4/mod/mod_ldap.html mod_ldap], documentation for mod_ldap, which provides connection pooling and a shared cache.
270 - [https://trac-hacks.org/wiki/LdapPlugin TracHacks:LdapPlugin] for storing TracPermissions in LDAP.
271
272=== Using SSPI Authentication
273
274If 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:
275{{{#!apache
276<Location /trac/login>
277  AuthType SSPI
278  AuthName "Trac Login"
279  SSPIAuth On
280  SSPIAuthoritative On
281  SSPIDomain MyLocalDomain
282  SSPIOfferBasic On
283  SSPIOmitDomain Off
284  SSPIBasicPreferred On
285  Require valid-user
286</Location>
287}}}
288
289Using 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.
290
291Some common problems with SSPI authentication: [trac:#1055], [trac:#1168] and [trac:#3338].
292
293See also [trac:TracOnWindows/Advanced].
294
295=== Using CA !SiteMinder Authentication
296
297Setup CA !SiteMinder to protect your Trac login URL, for example `/trac/login`. Also, make sure the policy is set to include the HTTP_REMOTE_USER variable. If your site allows it, you can set this in `LocalConfig.conf`:
298{{{#!apache
299RemoteUserVar="WHATEVER_IT_SHOULD_BE"
300SetRemoteUser="YES"
301}}}
302
303The specific variable is site-dependent. Ask your site administrator. If your site does not allow the use of `LocalConfig.conf` for security reasons, have your site administrator set the policy on the server to set REMOTE_USER.
304
305Also add a !LogOffUri parameter to the agent configuration, for example `/trac/logout`.
306
307Then modify the trac.wsgi script generated using `trac-admin <env> deploy <dir>` to add the following lines, which extract the `HTTP_REMOTE_USER` variable and set it to `REMOTE_USER`:
308
309{{{#!python
310def application(environ, start_request): 
311    # Set authenticated username on CA SiteMinder to REMOTE_USER variable
312    # strip() is used to remove any spaces on the end of the string
313    if 'HTTP_SM_USER' in environ: 
314        environ['REMOTE_USER'] = environ['HTTP_REMOTE_USER'].strip()
315    ...
316}}}
317
318You do not need any Apache "Location" directives.
319
320=== Example: Apache/mod_wsgi with Basic Authentication, Trac being at the root of a virtual host
321
322Per the mod_wsgi documentation linked to above, here is an example Apache configuration that:
323 - serves the Trac instance from a virtualhost subdomain
324 - uses Apache basic authentication for Trac authentication.
325
326If you want your Trac to be served from eg !http://trac.my-proj.my-site.org, then from the folder eg `/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:
327
328Create the htpasswd file:
329{{{#!sh
330cd /home/trac-for-my-proj/the-env
331htpasswd -c htpasswd firstuser
332### and add more users to it as needed:
333htpasswd htpasswd seconduser
334}}}
335
336Keep the file above your document root for security reasons.
337
338Create this file for example `/etc/apache2/sites-enabled/trac.my-proj.my-site.org.conf` on Ubuntu with the following content:
339
340{{{#!apache
341<Directory /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi>
342  WSGIApplicationGroup %{GLOBAL}
343  Order deny,allow
344  Allow from all
345</Directory>
346
347<VirtualHost *:80>
348  ServerName trac.my-proj.my-site.org
349  DocumentRoot /home/trac-for-my-proj/the-env/htdocs/
350  WSGIScriptAlias / /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi
351  <Location '/'>
352    AuthType Basic
353    AuthName "Trac"
354    AuthUserFile /home/trac-for-my-proj/the-env/htpasswd
355    Require valid-user
356  </Location>
357</VirtualHost>
358
359}}}
360
361For subdomains to work you would probably also need to alter `/etc/hosts` and add A-Records to your host's DNS.
362
363== Troubleshooting
364
365=== Use a recent version
366
367Please 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 [https://code.google.com/archive/p/modwsgi/issues/100 #100] and [https://code.google.com/archive/p/modwsgi/issues/132 #132].
368
369'''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
370
371If 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.
372
373=== Getting Trac to work nicely with SSPI and 'Require Group'
374
375If 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'.
376
377This WSGI script fixes that:
378{{{#!python
379import os
380import trac.web.main
381
382os.environ['TRAC_ENV'] = '/usr/local/trac/mysite'
383os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
384
385def application(environ, start_response):
386    if "\\" in environ['REMOTE_USER']:
387        environ['REMOTE_USER'] = environ['REMOTE_USER'].split("\\", 1)[1]
388    return trac.web.main.dispatch_request(environ, start_response)
389}}}
390
391=== Trac with PostgreSQL
392
393When 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.
394
395A 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.
396
397But it is not necessary to edit the source of Trac. The following lines in `trac.wsgi` will also work:
398
399{{{#!python
400import trac.db.postgres_backend
401trac.db.postgres_backend.PostgreSQLConnection.poolable = False
402}}}
403
404or
405
406{{{#!python
407import trac.db.mysql_backend
408trac.db.mysql_backend.MySQLConnection.poolable = False
409}}}
410
411Now Trac drops the connection after serving a page and the connection count on the database will be kept low.
412
413//This is not a recommended approach though. See also the notes at the bottom of the [https://code.google.com/archive/p/modwsgi/wikis/IntegrationWithTrac.wiki mod_wsgi's IntegrationWithTrac] wiki page.//
414
415=== Missing Headers and Footers
416
417If python optimizations are enabled, then headers and footers will not be rendered. An error will be raised in Trac 1.0.11 and later when optimizations are enabled.
418
419In your WSGI configuration file, the `WSGIPythonOptimize` setting must be set to `0` (`1` or `2` will not work):
420
421{{{#!apache
422    WSGIPythonOptimize 0
423}}}
424
425On Ubuntu, the WSGI mod configuration is at `/etc/apache2/mods-enabled/wsgi.conf`.
426
427The same issue is seen with `PythonOptimize On` in [TracModPython#Pagelayoutissues ModPython].
428
429=== Other resources
430
431For more troubleshooting tips, see also the [TracModPython#Troubleshooting mod_python troubleshooting] section, as most Apache-related issues are quite similar, plus discussion of potential [https://code.google.com/archive/p/modwsgi/wikis/ApplicationIssues.wiki application issues] when using mod_wsgi. The wsgi page also has a [https://code.google.com/archive/p/modwsgi/wikis/IntegrationWithTrac.wiki Integration With Trac] document.
432
433----
434See also: TracGuide, TracInstall, [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]
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