Changes between Version 1 and Version 2 of TracModWSGI


Ignore:
Timestamp:
May 5, 2015, 2:14:47 PM (3 years ago)
Author:
trac
Comment:

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  • TracModWSGI

    v1 v2  
    11= Trac and mod_wsgi =
    22
    3 '''Important note:''' ''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. 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].''
    4 
    5 [http://code.google.com/p/modwsgi/ mod_wsgi] is an Apache module for running WSGI-compatible Python applications directly on top of Apache. The mod_wsgi adapter is written completely in C and provides significantly better performance than using existing WSGI adapters for mod_python or CGI.
    6 
    7 Trac can be run on top of mod_wsgi with the help of the following application script, which is just a Python file, though usually saved with a .wsgi extension). This file can be created using '''trac-admin <env> deploy <dir>''' command which automatically substitutes required paths.
    8 
    9 {{{
    10 #!python
     3[http://code.google.com/p/modwsgi/ 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 the following application script, which is just a Python file, though usually saved with a `.wsgi` extension.
     10
     11=== A very basic script
     12In its simplest form, the script could be:
     13
     14{{{#!python
    1115import os
    1216
     
    1822}}}
    1923
    20 The `TRAC_ENV` variable should naturally be the directory for your Trac environment (if you have several Trac environments in a directory, you can also use `TRAC_ENV_PARENT_DIR` instead), while the `PYTHON_EGG_CACHE` should be a directory where Python can temporarily extract Python eggs.
    21 
    22 '''Important note:''' If you're 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. (The variable may be filled with the path of a previously viewed Trac environment.) To solve this problem, use the following `.wsgi` file instead:
    23 
    24 {{{
    25 #!python
     24The `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`.
     25
     26On Windows:
     27 - If run under the user's session, the Python Egg cache can be found in `%AppData%\Roaming`, for example:
     28{{{#!python
     29os.environ['PYTHON_EGG_CACHE'] = r'C:\Users\Administrator\AppData\Roaming\Python-Eggs'
     30}}}
     31 - If run under a Window service, you should create a directory for Python Egg cache:
     32{{{#!python
     33os.environ['PYTHON_EGG_CACHE'] = r'C:\Trac-Python-Eggs'
     34}}}
     35
     36=== A more elaborate script
     37
     38If 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.
     39
     40To solve this problem, use the following `.wsgi` file instead:
     41{{{#!python
    2642import os
    2743
     
    3450}}}
    3551
    36 For clarity, you should give this file a `.wsgi` extension. You should probably put the file in it's own directory, since you will open up its directory to Apache. You can create a .wsgi files which handles all this for you by running the TracAdmin command `deploy`.
    37 
    38 If you have installed trac and eggs in a path different from the standard one you should add that path by adding the following code on top of the wsgi script:
    39 
    40 {{{
    41 #!python
     52For 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.
     53
     54If 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:
     55
     56{{{#!python
    4257import site
    4358site.addsitedir('/usr/local/trac/lib/python2.4/site-packages')
    4459}}}
    4560
    46 Change it according to the path you installed the trac libs at.
    47 
    48 After you've done preparing your wsgi-script, add the following to your httpd.conf.
     61Change it according to the path you installed the Trac libs at.
     62
     63=== Recommended `trac.wsgi` script
     64
     65A somewhat 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.
     66
     67If you are using Trac with multiple projects, you can specify their common parent directory using the `TRAC_ENV_PARENT_DIR` in the trac.wsgi in trac.wsgi: ''
     68
     69{{{#!python
     70  def application(environ, start_request):
     71      Add this to config when you have multiple projects                                             
     72      environ.setdefault('trac.env_parent_dir', '/usr/share/trac/projects') 
     73      ..
     74      ..
     75}}}
     76
     77== Mapping requests to the script
     78
     79After preparing your .wsgi script, add the following to your Apache configuration file, typically `httpd.conf`:
    4980
    5081{{{
     
    5889}}}
    5990
    60 Here, the script is in a subdirectory of the Trac environment. 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 subinterpreters and may cause requests to hang or cause Apache to crash as a result. After adding this configuration, restart Apache, and then it should work.
    61 
    62 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):
    63 
    64 {{{
     91Here, the script is in a subdirectory of the Trac environment.
     92
     93If you followed the directions [TracInstall#cgi-bin Generating the Trac cgi-bin directory], your Apache configuration file should look like following:
     94
     95{{{
     96WSGIScriptAlias /trac /usr/share/trac/cgi-bin/trac.wsgi
     97
     98<Directory /usr/share/trac/cgi-bin>
     99    WSGIApplicationGroup %{GLOBAL}
     100    Order deny,allow
     101    Allow from all
     102</Directory>
     103}}}
     104
     105In 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.
     106
     107To 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):
     108
     109{{{#!python
    65110def application(environ, start_response):
    66111        start_response('200 OK',[('Content-type','text/html')])
     
    68113}}}
    69114
    70 See also the mod_wsgi [http://code.google.com/p/modwsgi/wiki/IntegrationWithTrac installation instructions] for Trac.
    71 
    72 For troubleshooting tips, see 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.
     115For 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.
     116
     117== Configuring Authentication
     118
     119The 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.
     120
     121=== Using Basic Authentication ===
     122
     123The simplest way to enable authentication with Apache is to create a password file. Use the `htpasswd` program as follows:
     124{{{
     125$ htpasswd -c /somewhere/trac.htpasswd admin
     126New password: <type password>
     127Re-type new password: <type password again>
     128Adding password for user admin
     129}}}
     130
     131After the first user, you don't need the "-c" option anymore:
     132{{{
     133$ htpasswd /somewhere/trac.htpasswd john
     134New password: <type password>
     135Re-type new password: <type password again>
     136Adding password for user john
     137}}}
     138
     139  ''See the man page for `htpasswd` for full documentation.''
     140
     141After you've created the users, you can set their permissions using TracPermissions.
     142
     143Now, you need to enable authentication against the password file in the Apache configuration:
     144{{{
     145<Location "/trac/login">
     146  AuthType Basic
     147  AuthName "Trac"
     148  AuthUserFile /somewhere/trac.htpasswd
     149  Require valid-user
     150</Location>
     151}}}
     152
     153If you are hosting multiple projects, you can use the same password file for all of them:
     154{{{
     155<LocationMatch "/trac/[^/]+/login">
     156  AuthType Basic
     157  AuthName "Trac"
     158  AuthUserFile /somewhere/trac.htpasswd
     159  Require valid-user
     160</LocationMatch>
     161}}}
     162Note that neither a file nor a directory named 'login' needs to exist.[[BR]]
     163See also the [http://httpd.apache.org/docs/2.2/mod/mod_auth_basic.html mod_auth_basic] documentation.
     164
     165=== Using Digest Authentication ===
     166
     167For better security, it is recommended that you either enable SSL or at least use the “digest” authentication scheme instead of “Basic”.
     168
     169You have to create your `.htpasswd` file with the `htdigest` command instead of `htpasswd`, as follows:
     170{{{
     171# htdigest -c /somewhere/trac.htpasswd trac admin
     172}}}
     173
     174The "trac" parameter above is the "realm", and will have to be reused in the Apache configuration in the !AuthName directive:
     175
     176{{{
     177<Location "/trac/login">
     178
     179    AuthType Digest
     180    AuthName "trac"
     181    AuthDigestDomain /trac
     182    AuthUserFile /somewhere/trac.htpasswd
     183    Require valid-user
     184</Location>
     185}}}
     186
     187For multiple environments, you can use the same `LocationMatch` as described with the previous method.
     188
     189'''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. '''
     190
     191Don't forget to activate the mod_auth_digest. For example, on a Debian 4.0r1 (etch) system:
     192{{{
     193    LoadModule auth_digest_module /usr/lib/apache2/modules/mod_auth_digest.so
     194}}}
     195
     196See also the [http://httpd.apache.org/docs/2.2/mod/mod_auth_digest.html mod_auth_digest] documentation.
     197
     198=== Using LDAP Authentication
     199
     200Configuration 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).
     201
     2021. You need to load the following modules in Apache httpd.conf:
     203{{{
     204LoadModule ldap_module modules/mod_ldap.so
     205LoadModule authnz_ldap_module modules/mod_authnz_ldap.so
     206}}}
     207
     2082. Your httpd.conf also needs to look something like:
     209
     210{{{
     211<Location /trac/>
     212  # (if you're using it, mod_python specific settings go here)
     213  Order deny,allow
     214  Deny from all
     215  Allow from 192.168.11.0/24
     216  AuthType Basic
     217  AuthName "Trac"
     218  AuthBasicProvider "ldap"
     219  AuthLDAPURL "ldap://127.0.0.1/dc=example,dc=co,dc=ke?uid?sub?(objectClass=inetOrgPerson)"
     220  authzldapauthoritative Off
     221  Require valid-user
     222</Location>
     223}}}
     224
     2253. You can use the LDAP interface as a way to authenticate to a Microsoft Active Directory:
     226
     227Use the following as your LDAP URL:
     228{{{
     229    AuthLDAPURL "ldap://directory.example.com:3268/DC=example,DC=com?sAMAccountName?sub?(objectClass=user)"
     230}}}
     231
     232You 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:
     233{{{
     234    AuthLDAPBindDN ldap-auth-user@example.com
     235    AuthLDAPBindPassword "password"
     236}}}
     237
     238The whole section looks like:
     239{{{
     240<Location /trac/>
     241  # (if you're using it, mod_python specific settings go here)
     242  Order deny,allow
     243  Deny from all
     244  Allow from 192.168.11.0/24
     245  AuthType Basic
     246  AuthName "Trac"
     247  AuthBasicProvider "ldap"
     248  AuthLDAPURL "ldap://adserver.company.com:3268/DC=company,DC=com?sAMAccountName?sub?(objectClass=user)"
     249  AuthLDAPBindDN       ldap-auth-user@company.com
     250  AuthLDAPBindPassword "the_password"
     251  authzldapauthoritative Off
     252  # require valid-user
     253  require ldap-group CN=Trac Users,CN=Users,DC=company,DC=com
     254</Location>
     255}}}
     256
     257Note 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.
     258
     259Note 2: You can also require the user be a member of a certain LDAP group, instead of just having a valid login:
     260{{{
     261    Require ldap-group CN=Trac Users,CN=Users,DC=example,DC=com
     262}}}
     263
     264See also:
     265 - [http://httpd.apache.org/docs/2.2/mod/mod_authnz_ldap.html mod_authnz_ldap], documentation for mod_authnz_ldap.   
     266 - [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.
     267 - [http://trac-hacks.org/wiki/LdapPlugin TracHacks:LdapPlugin] for storing TracPermissions in LDAP.
     268
     269=== Using SSPI Authentication
     270
     271If 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:
     272{{{
     273    <Location /trac/login>
     274        AuthType SSPI
     275        AuthName "Trac Login"
     276        SSPIAuth On
     277        SSPIAuthoritative On
     278        SSPIDomain MyLocalDomain
     279        SSPIOfferBasic On
     280        SSPIOmitDomain Off
     281        SSPIBasicPreferred On
     282        Require valid-user
     283    </Location>
     284}}}
     285
     286Using 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.
     287
     288Some common problems with SSPI authentication: [trac:#1055], [trac:#1168] and [trac:#3338].
     289
     290See also [trac:TracOnWindows/Advanced].
     291
     292=== Using Apache authentication with the Account Manager plugin's Login form ===
     293
     294To 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].
     295
     296'''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.
     297
     298Here is an example (from the !HttpAuthStore link) using acct_mgr-0.4 for hosting a single project:
     299{{{
     300[components]
     301; be sure to enable the component
     302acct_mgr.http.HttpAuthStore = enabled
     303
     304[account-manager]
     305; configure the plugin to use a page that is secured with http authentication
     306authentication_url = /authFile
     307password_store = HttpAuthStore
     308}}}
     309This will generally be matched with an Apache config like:
     310{{{
     311<Location /authFile>
     312   …HTTP authentication configuration…
     313   Require valid-user
     314</Location>
     315}}}
     316Note 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.
     317
     318=== Example: Apache/mod_wsgi with Basic Authentication, Trac being at the root of a virtual host
     319
     320Per the mod_wsgi documentation linked to above, here is an example Apache configuration that:
     321 - serves the Trac instance from a virtualhost subdomain
     322 - uses Apache basic authentication for Trac authentication.
     323
     324If 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:
     325
     326Create the htpasswd file:
     327{{{
     328cd /home/trac-for-my-proj/the-env
     329htpasswd -c htpasswd firstuser
     330### and add more users to it as needed:
     331htpasswd htpasswd seconduser
     332}}}
     333Keep the file above your document root for security reasons.
     334
     335Create this file e.g. (ubuntu) `/etc/apache2/sites-enabled/trac.my-proj.my-site.org.conf` with the following content:
     336
     337{{{
     338<Directory /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi>
     339  WSGIApplicationGroup %{GLOBAL}
     340  Order deny,allow
     341  Allow from all
     342</Directory>
     343
     344<VirtualHost *:80>
     345  ServerName trac.my-proj.my-site.org
     346  DocumentRoot /home/trac-for-my-proj/the-env/htdocs/
     347  WSGIScriptAlias / /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi
     348  <Location '/'>
     349    AuthType Basic
     350    AuthName "Trac"
     351    AuthUserFile /home/trac-for-my-proj/the-env/htpasswd
     352    Require valid-user
     353  </Location>
     354</VirtualHost>
     355
     356}}}
     357
     358Note: for subdomains to work you would probably also need to alter `/etc/hosts` and add A-Records to your host's DNS.
     359
     360== Troubleshooting
     361
     362=== Use a recent version
     363
     364Please 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].
    73365
    74366''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''
    75367
    76 == Trac with PostgreSQL ==
    77 
    78 When using the mod_wsgi adapter with multiple Trac instances and PostgreSQL (or MySQL?) as a database back-end the server can get a lot of open database connections. (and thus PostgreSQL processes)
    79 
    80 A workable solution is to disabled connection pooling in Trac. This is done by setting poolable = False in trac.db.postgres_backend on the PostgreSQLConnection class.
    81 
    82 But it's not necessary to edit the source of trac, the following lines in trac.wsgi will also work:
    83 
    84 {{{
    85 import trac.db.postgres_backend
    86 trac.db.postgres_backend.PostgreSQLConnection.poolable = False
    87 }}}
    88 
    89 Now Trac drops the connection after serving a page and the connection count on the database will be kept minimal.
    90 
    91 == Getting Trac to work nicely with SSPI and 'Require Group' ==
    92 If like me you've 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 its not working your usernames in trac are probably looking like 'DOMAIN\user' rather than 'user'.
    93 
    94 This WSGI script 'fixes' things, hope it helps:
    95 {{{
     368If you plan to use `mod_wsgi` in embedded mode on Windows or with the MPM worker on Linux, then you will need version 0.3.4 or greater. See [trac:#10675] for details.
     369
     370=== Getting Trac to work nicely with SSPI and 'Require Group' ===
     371
     372If 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'.
     373
     374This WSGI script 'fixes' that:
     375{{{#!python
    96376import os
    97377import trac.web.main
     
    105385    return trac.web.main.dispatch_request(environ, start_response)
    106386}}}
     387
     388=== Trac with PostgreSQL ===
     389
     390When 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.
     391
     392A 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.
     393
     394But it is not necessary to edit the source of Trac. The following lines in `trac.wsgi` will also work:
     395
     396{{{#!python
     397import trac.db.postgres_backend
     398trac.db.postgres_backend.PostgreSQLConnection.poolable = False
     399}}}
     400
     401or
     402
     403{{{#!python
     404import trac.db.mysql_backend
     405trac.db.mysql_backend.MySQLConnection.poolable = False
     406}}}
     407
     408Now Trac drops the connection after serving a page and the connection count on the database will be kept low.
     409
     410//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.//
     411
     412=== Other resources
     413
     414For 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.
     415
    107416----
    108 See also:  TracGuide, TracInstall, [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]
     417See also: TracGuide, TracInstall, [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]