Changes between Initial Version and Version 1 of TracModPython


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Timestamp:
Feb 24, 2010, 12:11:38 AM (5 years ago)
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trac
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  • TracModPython

    v1 v1  
     1= Trac and mod_python =
     2[[TracGuideToc]]
     3
     4Trac supports [http://www.modpython.org/ mod_python], which speeds up Trac's response times considerably, especially compared to [TracCgi CGI], and permits use of many Apache features not possible with [wiki:TracStandalone tracd]/mod_proxy.
     5
     6These instructions are for Apache 2; if you are still using Apache 1.3, you may have some luck with [trac:wiki:TracModPython2.7 TracModPython2.7].
     7
     8== Simple configuration ==
     9
     10If you just installed mod_python, you may have to add a line to load the module in the Apache configuration:
     11{{{
     12LoadModule python_module modules/mod_python.so
     13}}}
     14
     15''Note: The exact path to the module depends on how the HTTPD installation is laid out.''
     16
     17On Debian using apt-get
     18{{{
     19apt-get install libapache2-mod-python libapache2-mod-python-doc
     20}}}
     21(Still on Debian) after you have installed mod_python, you must enable the modules in apache2 (equivalent of the above Load Module directive):
     22{{{
     23a2enmod mod_python
     24}}}
     25On Fedora use, using yum:
     26{{{
     27yum install mod_python
     28}}}
     29You can test your mod_python installation by adding the following to your httpd.conf.  You should remove this when you are done testing for security reasons. Note: mod_python.testhandler is only available in mod_python 3.2+.
     30{{{
     31#!xml
     32<Location /mpinfo>
     33   SetHandler mod_python
     34   PythonInterpreter main_interpreter
     35   PythonHandler mod_python.testhandler
     36</Location>
     37}}}
     38
     39A simple setup of Trac on mod_python looks like this:
     40{{{
     41#!xml
     42<Location /projects/myproject>
     43   SetHandler mod_python
     44   PythonInterpreter main_interpreter
     45   PythonHandler trac.web.modpython_frontend
     46   PythonOption TracEnv /var/trac/myproject
     47   PythonOption TracUriRoot /projects/myproject
     48</Location>
     49}}}
     50
     51The option '''`TracUriRoot`''' may or may not be necessary in your setup. Try your configuration without it; if the URLs produced by Trac look wrong, if Trac does not seem to recognize URLs correctly, or you get an odd "No handler matched request to..." error, add the '''`TracUriRoot`''' option.  You will notice that the `Location` and '''`TracUriRoot`''' have the same path.
     52
     53The options available are
     54{{{
     55    # For a single project
     56    PythonOption TracEnv /var/trac/myproject
     57    # For multiple projects
     58    PythonOption TracEnvParentDir /var/trac/myprojects
     59    # For the index of multiple projects
     60    PythonOption TracEnvIndexTemplate /srv/www/htdocs/trac/project_list_template.html
     61    # A space delimitted list, with a "," between key and value pairs.
     62    PythonOption TracTemplateVars key1,val1 key2,val2
     63    # Useful to get the date in the wanted order
     64    PythonOption TracLocale en_GB.UTF8
     65    # See description above       
     66    PythonOption TracUriRoot /projects/myproject
     67}}}
     68
     69=== Python Egg Cache ===
     70
     71Compressed python eggs like Genshi are normally extracted into a directory named `.python-eggs` in the users home directory. Since apache's home usually is not writable an alternate egg cache directory can be specified like this:
     72{{{
     73PythonOption PYTHON_EGG_CACHE /var/trac/myprojects/egg-cache
     74}}}
     75
     76or you can uncompress the Genshi egg to resolve problems extracting from it.
     77=== Configuring Authentication ===
     78
     79Creating password files and configuring authentication works similar to the process for [wiki:TracCgi#AddingAuthentication CGI]:
     80{{{
     81#!xml
     82<Location /projects/myproject/login>
     83  AuthType Basic
     84  AuthName "myproject"
     85  AuthUserFile /var/trac/myproject/.htpasswd
     86  Require valid-user
     87</Location>
     88}}}
     89
     90Configuration for mod_ldap authentication in Apache is a bit tricky (httpd 2.2.x and OpenLDAP: slapd 2.3.19)
     91
     921. You need to load the following modules in Apache httpd.conf
     93{{{
     94LoadModule ldap_module modules/mod_ldap.so
     95LoadModule authnz_ldap_module modules/mod_authnz_ldap.so
     96}}}
     97
     982. Your httpd.conf also needs to look something like:
     99
     100{{{
     101#!xml
     102<Location /trac/>
     103  SetHandler mod_python
     104  PythonInterpreter main_interpreter
     105  PythonHandler trac.web.modpython_frontend
     106  PythonOption TracEnv /home/trac/
     107  PythonOption TracUriRoot /trac/
     108  Order deny,allow
     109  Deny from all
     110  Allow from 192.168.11.0/24
     111  AuthType Basic
     112  AuthName "Trac"
     113  AuthBasicProvider "ldap"
     114  AuthLDAPURL "ldap://127.0.0.1/dc=example,dc=co,dc=ke?uid?sub?(objectClass=inetOrgPerson)"
     115  authzldapauthoritative Off
     116  require valid-user
     117</Location>
     118}}}
     119
     120Or the LDAP interface to a Microsoft Active Directory:
     121
     122{{{
     123#!xml
     124<Location /trac/>
     125  SetHandler mod_python
     126  PythonInterpreter main_interpreter
     127  PythonHandler trac.web.modpython_frontend
     128  PythonOption TracEnv /home/trac/
     129  PythonOption TracUriRoot /trac/
     130  Order deny,allow
     131  Deny from all
     132  Allow from 192.168.11.0/24
     133  AuthType Basic
     134  AuthName "Trac"
     135  AuthBasicProvider "ldap"
     136  AuthLDAPURL "ldap://adserver.company.com:3268/DC=company,DC=com?sAMAccountName?sub?(objectClass=user)"
     137  AuthLDAPBindDN       ldap-auth-user@company.com
     138  AuthLDAPBindPassword "the_password"
     139  authzldapauthoritative Off
     140  # require valid-user
     141  require ldap-group CN=Trac Users,CN=Users,DC=company,DC=com
     142</Location>
     143}}}
     144
     145Note 1: This is the case where the LDAP search will get around the multiple OUs, conecting to Global Catalog Server portion of AD (Notice 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.
     146
     147Note 2: Active Directory requires an authenticating user/password to access records (AuthLDAPBindDN and AuthLDAPBindPassword).
     148
     149Note 3: The directive "require ldap-group ..."  specifies an AD group whose members are allowed access.
     150
     151
     152=== Setting the Python Egg Cache ===
     153
     154If the Egg Cache isn't writeable by your Web server, you'll either have to change the permissions, or point Python to a location where Apache can write. This can manifest itself as a ''500 internal server error'' and/or a complaint in the syslog.
     155
     156{{{
     157#!xml
     158<Location /projects/myproject>
     159  ...
     160  PythonOption PYTHON_EGG_CACHE /tmp
     161  ...
     162</Location>
     163}}}
     164
     165
     166=== Setting the !PythonPath ===
     167
     168If the Trac installation isn't installed in your Python path, you'll have to tell Apache where to find the Trac mod_python handler  using the `PythonPath` directive:
     169{{{
     170#!xml
     171<Location /projects/myproject>
     172  ...
     173  PythonPath "sys.path + ['/path/to/trac']"
     174  ...
     175</Location>
     176}}}
     177
     178Be careful about using the !PythonPath directive, and ''not'' `SetEnv PYTHONPATH`, as the latter won't work.
     179
     180== Setting up multiple projects ==
     181
     182The Trac mod_python handler supports a configuration option similar to Subversion's `SvnParentPath`, called `TracEnvParentDir`:
     183{{{
     184#!xml
     185<Location /projects>
     186  SetHandler mod_python
     187  PythonInterpreter main_interpreter
     188  PythonHandler trac.web.modpython_frontend
     189  PythonOption TracEnvParentDir /var/trac
     190  PythonOption TracUriRoot /projects
     191</Location>
     192}}}
     193
     194When you request the `/projects` URL, you will get a listing of all subdirectories of the directory you set as `TracEnvParentDir` that look like Trac environment directories. Selecting any project in the list will bring you to the corresponding Trac environment.
     195
     196If you don't want to have the subdirectory listing as your projects home page you can use a
     197{{{
     198#!xml
     199<LocationMatch "/.+/">
     200}}}
     201
     202This will instruct Apache to use mod_python for all locations different from root while having the possibility of placing a custom home page for root in your !DocumentRoot folder.
     203
     204You can also use the same authentication realm for all of the projects using a `<LocationMatch>` directive:
     205{{{
     206#!xml
     207<LocationMatch "/projects/[^/]+/login">
     208  AuthType Basic
     209  AuthName "Trac"
     210  AuthUserFile /var/trac/.htpasswd
     211  Require valid-user
     212</LocationMatch>
     213}}}
     214
     215== Virtual Host Configuration ==
     216
     217Below is the sample configuration required to set up your trac as a virtual server (i.e. when you access it at the URLs like
     218!http://trac.mycompany.com):
     219
     220{{{
     221#!xml
     222<VirtualHost * >
     223    DocumentRoot /var/www/myproject
     224    ServerName trac.mycompany.com
     225    <Location />
     226        SetHandler mod_python
     227        PythonInterpreter main_interpreter
     228        PythonHandler trac.web.modpython_frontend
     229        PythonOption TracEnv /var/trac/myproject
     230        PythonOption TracUriRoot /
     231    </Location>
     232    <Location /login>
     233        AuthType Basic
     234        AuthName "MyCompany Trac Server"
     235        AuthUserFile /var/trac/myproject/.htpasswd
     236        Require valid-user
     237    </Location>
     238</VirtualHost>
     239}}}
     240
     241This does not seem to work in all cases. What you can do if it does not:
     242 * Try using `<LocationMatch>` instead of `<Location>`
     243 * <Location /> may, in your server setup, refer to the complete host instead of simple the root of the server. This means that everything (including the login directory referenced below) will be sent to python and authentication does not work (i.e. you get the infamous Authentication information missing error). If this applies to you, try using a sub-directory for trac instead of the root (i.e. /web/ and /web/login instead of / and /login).
     244 * Depending on apache's `NameVirtualHost` configuration, you may need to use `<VirtualHost *:80>` instead of `<VirtualHost *>`.
     245
     246For a virtual host that supports multiple projects replace "`TracEnv`" /var/trac/myproject with "`TracEnvParentDir`" /var/trac/
     247
     248Note: !DocumentRoot should not point to your Trac project env. As Asmodai wrote on #trac: "suppose there's a webserver bug that allows disclosure of !DocumentRoot they could then leech the entire Trac environment".
     249
     250== Troubleshooting ==
     251
     252In general, if you get server error pages, you can either check the Apache error log, or enable the `PythonDebug` option:
     253{{{
     254#!xml
     255<Location /projects/myproject>
     256  ...
     257  PythonDebug on
     258</Location>
     259}}}
     260
     261For multiple projects, try restarting the server as well.
     262
     263=== Expat-related segmentation faults === #expat
     264
     265This problem will most certainly hit you on Unix when using Python 2.4.
     266In Python 2.4, some version of Expat (an XML parser library written in C) is used,
     267and if Apache is using another version, this results in segmentation faults.
     268As Trac 0.11 is using Genshi, which will indirectly use Expat, that problem
     269can now hit you even if everything was working fine before with Trac 0.10.
     270
     271See Graham Dumpleton's detailed [http://www.dscpl.com.au/wiki/ModPython/Articles/ExpatCausingApacheCrash explanation and workarounds] for the issue.
     272
     273=== Form submission problems ===
     274
     275If you're experiencing problems submitting some of the forms in Trac (a common problem is that you get redirected to the start page after submission), check whether your {{{DocumentRoot}}} contains a folder or file with the same path that you mapped the mod_python handler to. For some reason, mod_python gets confused when it is mapped to a location that also matches a static resource.
     276
     277=== Problem with virtual host configuration ===
     278
     279If the <Location /> directive is used, setting the `DocumentRoot` may result in a ''403 (Forbidden)'' error. Either remove the `DocumentRoot` directive, or make sure that accessing the directory it points is allowed (in a corresponding `<Directory>` block).
     280
     281Using <Location /> together with `SetHandler` resulted in having everything handled by mod_python, which leads to not being able download any CSS or images/icons. I used <Location /trac> `SetHandler None` </Location> to circumvent the problem, though I do not know if this is the most elegant solution.
     282
     283=== Using .htaccess ===
     284
     285Although it may seem trivial to rewrite the above configuration as a directory in your document root with a `.htaccess` file, this does not work. Apache will append a "/" to any Trac URLs, which interferes with its correct operation.
     286
     287It may be possible to work around this with mod_rewrite, but I failed to get this working. In all, it is more hassle than it is worth. Stick to the provided instructions. :)
     288
     289A success story: For me it worked out-of-box, with following trivial config:
     290{{{
     291SetHandler mod_python
     292PythonInterpreter main_interpreter
     293PythonHandler trac.web.modpython_frontend
     294PythonOption TracEnv /system/path/to/this/directory
     295PythonOption TracUriRoot /path/on/apache
     296
     297AuthType Basic
     298AuthName "ProjectName"
     299AuthUserFile /path/to/.htpasswd
     300Require valid-user
     301}}}
     302
     303The `TracUriRoot` is obviously the path you need to enter to the browser to get to the trac (e.g. domain.tld/projects/trac)
     304
     305=== Additional .htaccess help ===
     306
     307If you are using the .htaccess method you may have additional problems if your trac directory is inheriting .htaccess directives from another.  This may also help to add to your .htaccess file:
     308
     309{{{
     310<IfModule mod_rewrite.c>
     311  RewriteEngine Off
     312</IfModule>
     313}}}
     314
     315
     316=== Win32 Issues ===
     317If you run trac with mod_python < 3.2 on Windows, uploading attachments will '''not''' work. This problem is resolved in mod_python 3.1.4 or later, so please upgrade mod_python to fix this.
     318
     319
     320=== OS X issues ===
     321
     322When using mod_python on OS X you will not be able to restart Apache using `apachectl restart`. This is apparently fixed in mod_python 3.2, but there's also a patch available for earlier versions [http://www.dscpl.com.au/projects/vampire/patches.html here].
     323
     324=== SELinux issues ===
     325
     326If Trac reports something like: ''Cannot get shared lock on db.lock''
     327The security context on the repository may need to be set:
     328
     329{{{
     330chcon -R -h -t httpd_sys_content_t PATH_TO_REPOSITORY
     331}}}
     332
     333See also [http://subversion.tigris.org/faq.html#reposperms]
     334
     335=== FreeBSD issues ===
     336Pay attention to the version of the installed mod_python and sqlite packages. Ports have both the new and old ones, but earlier versions of pysqlite and mod_python won't integrate as the former requires threaded support in python, and the latter requires a threadless install.
     337
     338If you compiled and installed apache2, apache wouldn´t support threads (cause it doesn´t work very well on FreeBSD). You could force thread support when running ./configure for apache, using --enable-threads, but this isn´t recommendable.
     339The best option [http://modpython.org/pipermail/mod_python/2006-September/021983.html seems to be] adding to /usr/local/apache2/bin/ennvars the line
     340
     341{{{
     342export LD_PRELOAD=/usr/lib/libc_r.so
     343}}}
     344
     345=== Subversion issues ===
     346
     347If you get the following Trac Error `Unsupported version control system "svn"` only under mod_python, though it works well on the command-line and even with TracStandalone, chances are that you forgot to add the path to the Python bindings with the [TracModPython#ConfiguringPythonPath PythonPath] directive. (The better way is to add a link to the bindings in the Python `site-packages` directory, or create a `.pth` file in that directory.)
     348
     349If this is not the case, it's possible that you're using Subversion libraries that are binary incompatible with the apache ones (an incompatibility of the `apr` libraries is usually the cause). In that case, you also won't be able to use the svn modules for Apache (`mod_dav_svn`).
     350
     351You also need a recent version of `mod_python` in order to avoid a runtime error ({{{argument number 2: a 'apr_pool_t *' is expected}}}) due to the default usage of multiple sub-interpreters. 3.2.8 ''should'' work, though it's probably better to use the workaround described in [trac:#3371 #3371], in order to force the use of the main interpreter:
     352{{{
     353PythonInterpreter main_interpreter
     354}}}
     355This is anyway the recommended workaround for other well-known issues seen when using the Python bindings for Subversion within mod_python ([trac:#2611 #2611], [trac:#3455 #3455]). See in particular Graham Dumpleton's comment in [trac:comment:9:ticket:3455 #3455] explaining the issue.
     356
     357=== Page layout issues ===
     358
     359If the formatting of the Trac pages look weird chances are that the style sheets governing the page layout are not handled properly by the web server. Try adding the following lines to your apache configuration:
     360{{{
     361#!xml
     362Alias /myproject/css "/usr/share/trac/htdocs/css"
     363<Location /myproject/css>
     364    SetHandler None
     365</Location>
     366}}}
     367
     368Note: For the above configuration to have any effect it must be put after the configuration of your project root location, i.e. {{{<Location /myproject />}}}.
     369
     370=== HTTPS issues ===
     371
     372If you want to run Trac fully under https you might find that it tries to redirect to plain http. In this case just add the following line to your apache configuration:
     373{{{
     374#!xml
     375<VirtualHost * >
     376    DocumentRoot /var/www/myproject
     377    ServerName trac.mycompany.com
     378    SetEnv HTTPS 1
     379    ....
     380</VirtualHost>
     381}}}
     382
     383=== Fedora 7 Issues ===
     384Make sure you install the 'python-sqlite2' package as it seems to be required for TracModPython but not for tracd
     385
     386
     387=== Segmentation fault with php5-mhash or other php5 modules ===
     388You may encounter segfaults (reported on debian etch) if php5-mhash module is installed. Try to remove it to see if this solves the problem. See debian bug report [http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=411487]
     389
     390Some people also have troubles when using php5 compiled with its own 3rd party libraries instead of system libraries. Check here [http://www.djangoproject.com/documentation/modpython/#if-you-get-a-segmentation-fault]
     391
     392----
     393See also:  TracGuide, TracInstall, [wiki:TracModWSGI ModWSGI], [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]