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  • wiki/pages/TracModWSGI

    r37343 r37566  
    1 = Trac and mod_wsgi
    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.
    5 [[PageOutline(2-3,Overview,inline)]]
    7 == The `trac.wsgi` script
    9 Trac 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.
    11 A 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].
    13 If 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
    15 def 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 }}}
    21 === A very basic script
    22 In its simplest form, the script could be:
    24 {{{#!python
    25 import os
    27 os.environ['TRAC_ENV'] = '/usr/local/trac/mysite'
    28 os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
    30 import trac.web.main
    31 application = trac.web.main.dispatch_request
    32 }}}
    34 The `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 On Windows:
    37  - If run under the user's session, the Python Egg cache can be found in `%AppData%\Roaming`, for example:
    38 {{{#!python
    39 os.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
    43 os.environ['PYTHON_EGG_CACHE'] = r'C:\Trac-Python-Eggs'
    44 }}}
    46 === A more elaborate script
    48 If 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 To solve this problem, use the following `.wsgi` file instead:
    51 {{{#!python
    52 import os
    54 os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
    56 import trac.web.main
    57 def application(environ, start_response):
    58   environ['trac.env_path'] = '/usr/local/trac/mysite'
    59   return trac.web.main.dispatch_request(environ, start_response)
    60 }}}
    62 For 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 If 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 {{{#!python
    67 import site
    68 site.addsitedir('/usr/local/trac/lib/python2.4/site-packages')
    69 }}}
    71 Change it according to the path you installed the Trac libs at.
    73 == Mapping requests to the script
    75 After preparing your .wsgi script, add the following to your Apache configuration file, typically `httpd.conf`:
    77 {{{#!apache
    78 WSGIScriptAlias /trac /usr/local/trac/mysite/apache/mysite.wsgi
    80 <Directory /usr/local/trac/mysite/apache>
    81     WSGIApplicationGroup %{GLOBAL}
    82     Order deny,allow
    83     Allow from all
    84 </Directory>
    85 }}}
    87 Here, the script is in a subdirectory of the Trac environment.
    89 If you followed the directions [TracInstall#cgi-bin Generating the Trac cgi-bin directory], your Apache configuration file should look like following:
    91 {{{#!apache
    92 WSGIScriptAlias /trac /usr/share/trac/cgi-bin/trac.wsgi
    94 <Directory /usr/share/trac/cgi-bin>
    95     WSGIApplicationGroup %{GLOBAL}
    96     Order deny,allow
    97     Allow from all
    98 </Directory>
    99 }}}
    101 In 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.
    103 To 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):
    105 {{{#!python
    106 def application(environ, start_response):
    107         start_response('200 OK',[('Content-type','text/html')])
    108         return ['<html><body>Hello World!</body></html>']
    109 }}}
    111 For 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.
    113 == Configuring Authentication
    115 The 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.
    117 === Using Basic Authentication
    119 The 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
    122 New password: <type password>
    123 Re-type new password: <type password again>
    124 Adding password for user admin
    125 }}}
    127 After the first user, you don't need the "-c" option anymore:
    128 {{{#!sh
    129 $ htpasswd /somewhere/trac.htpasswd john
    130 New password: <type password>
    131 Re-type new password: <type password again>
    132 Adding password for user john
    133 }}}
    135   ''See the man page for `htpasswd` for full documentation.''
    137 After you've created the users, you can set their permissions using TracPermissions.
    139 Now, 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 }}}
    149 If 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 }}}
    158 Note that neither a file nor a directory named 'login' needs to exist.[[BR]]
    159 See also the [http://httpd.apache.org/docs/2.2/mod/mod_auth_basic.html mod_auth_basic] documentation.
    161 === Using Digest Authentication
    163 For better security, it is recommended that you either enable SSL or at least use the “digest” authentication scheme instead of “Basic”.
    165 You 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 }}}
    170 The "trac" parameter above is the "realm", and will have to be reused in the Apache configuration in the !AuthName directive:
    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 }}}
    182 For multiple environments, you can use the same `LocationMatch` as described with the previous method.
    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. '''
    186 Don'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 }}}
    191 See also the [http://httpd.apache.org/docs/2.2/mod/mod_auth_digest.html mod_auth_digest] documentation.
    193 === Using LDAP Authentication
    195 Configuration 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).
    197 1. 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 }}}
    202 1. 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
    209   AuthType Basic
    210   AuthName "Trac"
    211   AuthBasicProvider "ldap"
    212   AuthLDAPURL "ldap://,dc=co,dc=ke?uid?sub?(objectClass=inetOrgPerson)"
    213   authzldapauthoritative Off
    214   Require valid-user
    215 </Location>
    216 }}}
    217 1. 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
    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 }}}
    245 Note 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.
    247 Note 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 }}}
    252 See 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.
    257 === Using SSPI Authentication
    259 If 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 }}}
    274 Using 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.
    276 Some common problems with SSPI authentication: [trac:#1055], [trac:#1168] and [trac:#3338].
    278 See also [trac:TracOnWindows/Advanced].
    280 === Using Apache authentication with the Account Manager plugin's Login form ===
    282 To 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].
    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.
    286 Here 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
    290 acct_mgr.http.HttpAuthStore = enabled
    292 [account-manager]
    293 ; configure the plugin to use a page that is secured with http authentication
    294 authentication_url = /authFile
    295 password_store = HttpAuthStore
    296 }}}
    297 This 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 }}}
    304 Note 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.
    306 === Example: Apache/mod_wsgi with Basic Authentication, Trac being at the root of a virtual host
    308 Per 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.
    312 If 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:
    314 Create the htpasswd file:
    315 {{{#!sh
    316 cd /home/trac-for-my-proj/the-env
    317 htpasswd -c htpasswd firstuser
    318 ### and add more users to it as needed:
    319 htpasswd htpasswd seconduser
    320 }}}
    321 Keep the file above your document root for security reasons.
    323 Create this file e.g. (ubuntu) `/etc/apache2/sites-enabled/trac.my-proj.my-site.org.conf` with the following content:
    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>
    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>
    344 }}}
    346 Note: for subdomains to work you would probably also need to alter `/etc/hosts` and add A-Records to your host's DNS.
    348 == Troubleshooting
    350 === Use a recent version
    352 Please 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].
    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 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''
    356 If 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.
    358 === Getting Trac to work nicely with SSPI and 'Require Group'
    360 If 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'.
    362 This WSGI script 'fixes' that:
    363 {{{#!python
    364 import os
    365 import trac.web.main
    367 os.environ['TRAC_ENV'] = '/usr/local/trac/mysite'
    368 os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
    370 def 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 }}}
    376 === Trac with PostgreSQL
    378 When 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.
    380 A 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.
    382 But it is not necessary to edit the source of Trac. The following lines in `trac.wsgi` will also work:
    384 {{{#!python
    385 import trac.db.postgres_backend
    386 trac.db.postgres_backend.PostgreSQLConnection.poolable = False
    387 }}}
    389 or
    391 {{{#!python
    392 import trac.db.mysql_backend
    393 trac.db.mysql_backend.MySQLConnection.poolable = False
    394 }}}
    396 Now Trac drops the connection after serving a page and the connection count on the database will be kept low.
    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.//
    400 === Other resources
    402 For 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.
    404 ----
    405 See also: TracGuide, TracInstall, [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]
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