Changes between Version 1 and Version 2 of TracModWSGI


Ignore:
Timestamp:
22 Apr 2015 15:34:51 (5 years ago)
Author:
trac
Comment:

--

Legend:

Unmodified
Added
Removed
Modified
  • TracModWSGI

    v1 v2  
    1 = Trac and mod_wsgi =
    2 
    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
     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
    1125import os
    1226
     
    1832}}}
    1933
    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
     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
    2652import os
    2753
     
    3460}}}
    3561
    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
     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
    4267import site
    4368site.addsitedir('/usr/local/trac/lib/python2.4/site-packages')
    4469}}}
    4570
    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.
    49 
    50 {{{
     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
    5178WSGIScriptAlias /trac /usr/local/trac/mysite/apache/mysite.wsgi
    5279
     
    5885}}}
    5986
    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 {{{
     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
    65106def application(environ, start_response):
    66107        start_response('200 OK',[('Content-type','text/html')])
     
    68109}}}
    69110
    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.
     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].
    73353
    74354''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''
    75355
    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 {{{
     356If 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.
     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
    96364import os
    97365import trac.web.main
     
    105373    return trac.web.main.dispatch_request(environ, start_response)
    106374}}}
     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
    107404----
    108 See also:  TracGuide, TracInstall, [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]
     405See also: TracGuide, TracInstall, [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]