Changes between Initial Version and Version 1 of TracModPython


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Timestamp:
01/30/12 14:43:47 (6 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== A Word of Warning == 
     9 
     10As of 16^th^ June 2010, the mod_python project is officially dead.  If you are considering using mod_python for a new installation, '''please don't'''!  There are known issues which will not be fixed and there are now better alternatives.  Check out the main TracInstall pages for your target version for more information. 
     11 
     12== Simple configuration == 
     13 
     14If you just installed mod_python, you may have to add a line to load the module in the Apache configuration: 
     15{{{ 
     16LoadModule python_module modules/mod_python.so 
     17}}} 
     18 
     19''Note: The exact path to the module depends on how the HTTPD installation is laid out.'' 
     20 
     21On Debian using apt-get 
     22{{{ 
     23apt-get install libapache2-mod-python libapache2-mod-python-doc 
     24}}} 
     25(Still on Debian) after you have installed mod_python, you must enable the modules in apache2 (equivalent of the above Load Module directive): 
     26{{{ 
     27a2enmod python 
     28}}} 
     29On Fedora use, using yum: 
     30{{{ 
     31yum install mod_python 
     32}}} 
     33You 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+. 
     34{{{ 
     35#!xml 
     36<Location /mpinfo> 
     37   SetHandler mod_python 
     38   PythonInterpreter main_interpreter 
     39   PythonHandler mod_python.testhandler 
     40   Order allow,deny 
     41   Allow from all 
     42</Location> 
     43}}} 
     44 
     45A simple setup of Trac on mod_python looks like this: 
     46{{{ 
     47#!xml 
     48<Location /projects/myproject> 
     49   SetHandler mod_python 
     50   PythonInterpreter main_interpreter 
     51   PythonHandler trac.web.modpython_frontend  
     52   PythonOption TracEnv /var/trac/myproject 
     53   PythonOption TracUriRoot /projects/myproject 
     54   Order allow,deny 
     55   Allow from all 
     56</Location> 
     57}}} 
     58 
     59The 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. 
     60 
     61The options available are 
     62{{{ 
     63    # For a single project 
     64    PythonOption TracEnv /var/trac/myproject 
     65    # For multiple projects 
     66    PythonOption TracEnvParentDir /var/trac/myprojects 
     67    # For the index of multiple projects 
     68    PythonOption TracEnvIndexTemplate /srv/www/htdocs/trac/project_list_template.html 
     69    # A space delimitted list, with a "," between key and value pairs. 
     70    PythonOption TracTemplateVars key1,val1 key2,val2 
     71    # Useful to get the date in the wanted order 
     72    PythonOption TracLocale en_GB.UTF8 
     73    # See description above         
     74    PythonOption TracUriRoot /projects/myproject 
     75}}} 
     76 
     77=== Python Egg Cache === 
     78 
     79Compressed 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: 
     80{{{ 
     81PythonOption PYTHON_EGG_CACHE /var/trac/myprojects/egg-cache 
     82}}} 
     83 
     84or you can uncompress the Genshi egg to resolve problems extracting from it. 
     85=== Configuring Authentication === 
     86 
     87Creating password files and configuring authentication works similar to the process for [wiki:TracCgi#AddingAuthentication CGI]: 
     88{{{ 
     89#!xml 
     90<Location /projects/myproject/login> 
     91  AuthType Basic 
     92  AuthName "myproject" 
     93  AuthUserFile /var/trac/myproject/.htpasswd 
     94  Require valid-user 
     95</Location> 
     96}}} 
     97 
     98Configuration for mod_ldap authentication in Apache is a bit tricky (httpd 2.2.x and OpenLDAP: slapd 2.3.19) 
     99 
     1001. You need to load the following modules in Apache httpd.conf 
     101{{{ 
     102LoadModule ldap_module modules/mod_ldap.so 
     103LoadModule authnz_ldap_module modules/mod_authnz_ldap.so 
     104}}} 
     105 
     1062. Your httpd.conf also needs to look something like: 
     107 
     108{{{ 
     109#!xml 
     110<Location /trac/> 
     111  SetHandler mod_python 
     112  PythonInterpreter main_interpreter 
     113  PythonHandler trac.web.modpython_frontend 
     114  PythonOption TracEnv /home/trac/ 
     115  PythonOption TracUriRoot /trac/ 
     116  Order deny,allow 
     117  Deny from all 
     118  Allow from 192.168.11.0/24 
     119  AuthType Basic 
     120  AuthName "Trac" 
     121  AuthBasicProvider "ldap" 
     122  AuthLDAPURL "ldap://127.0.0.1/dc=example,dc=co,dc=ke?uid?sub?(objectClass=inetOrgPerson)" 
     123  authzldapauthoritative Off 
     124  require valid-user 
     125</Location> 
     126}}} 
     127 
     128Or the LDAP interface to a Microsoft Active Directory: 
     129 
     130{{{ 
     131#!xml 
     132<Location /trac/> 
     133  SetHandler mod_python 
     134  PythonInterpreter main_interpreter 
     135  PythonHandler trac.web.modpython_frontend 
     136  PythonOption TracEnv /home/trac/ 
     137  PythonOption TracUriRoot /trac/ 
     138  Order deny,allow 
     139  Deny from all 
     140  Allow from 192.168.11.0/24 
     141  AuthType Basic 
     142  AuthName "Trac" 
     143  AuthBasicProvider "ldap" 
     144  AuthLDAPURL "ldap://adserver.company.com:3268/DC=company,DC=com?sAMAccountName?sub?(objectClass=user)" 
     145  AuthLDAPBindDN       ldap-auth-user@company.com 
     146  AuthLDAPBindPassword "the_password" 
     147  authzldapauthoritative Off 
     148  # require valid-user 
     149  require ldap-group CN=Trac Users,CN=Users,DC=company,DC=com 
     150</Location> 
     151}}} 
     152 
     153Note 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. 
     154 
     155Note 2: Active Directory requires an authenticating user/password to access records (AuthLDAPBindDN and AuthLDAPBindPassword). 
     156 
     157Note 3: The directive "require ldap-group ..."  specifies an AD group whose members are allowed access. 
     158 
     159 
     160=== Setting the Python Egg Cache === 
     161 
     162If 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.  
     163 
     164{{{ 
     165#!xml 
     166<Location /projects/myproject> 
     167  ... 
     168  PythonOption PYTHON_EGG_CACHE /tmp  
     169  ... 
     170</Location> 
     171}}} 
     172 
     173 
     174=== Setting the !PythonPath === 
     175 
     176If 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: 
     177{{{ 
     178#!xml 
     179<Location /projects/myproject> 
     180  ... 
     181  PythonPath "sys.path + ['/path/to/trac']" 
     182  ... 
     183</Location> 
     184}}} 
     185 
     186Be careful about using the !PythonPath directive, and ''not'' `SetEnv PYTHONPATH`, as the latter won't work. 
     187 
     188== Setting up multiple projects == 
     189 
     190The Trac mod_python handler supports a configuration option similar to Subversion's `SvnParentPath`, called `TracEnvParentDir`: 
     191{{{ 
     192#!xml 
     193<Location /projects> 
     194  SetHandler mod_python 
     195  PythonInterpreter main_interpreter 
     196  PythonHandler trac.web.modpython_frontend  
     197  PythonOption TracEnvParentDir /var/trac 
     198  PythonOption TracUriRoot /projects 
     199</Location> 
     200}}} 
     201 
     202When 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. 
     203 
     204If you don't want to have the subdirectory listing as your projects home page you can use a 
     205{{{ 
     206#!xml 
     207<LocationMatch "/.+/"> 
     208}}} 
     209 
     210This 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. 
     211 
     212You can also use the same authentication realm for all of the projects using a `<LocationMatch>` directive: 
     213{{{ 
     214#!xml 
     215<LocationMatch "/projects/[^/]+/login"> 
     216  AuthType Basic 
     217  AuthName "Trac" 
     218  AuthUserFile /var/trac/.htpasswd 
     219  Require valid-user 
     220</LocationMatch> 
     221}}} 
     222 
     223== Virtual Host Configuration == 
     224 
     225Below is the sample configuration required to set up your trac as a virtual server (i.e. when you access it at the URLs like 
     226!http://trac.mycompany.com): 
     227 
     228{{{ 
     229#!xml 
     230<VirtualHost * > 
     231    DocumentRoot /var/www/myproject 
     232    ServerName trac.mycompany.com 
     233    <Location /> 
     234        SetHandler mod_python 
     235        PythonInterpreter main_interpreter 
     236        PythonHandler trac.web.modpython_frontend 
     237        PythonOption TracEnv /var/trac/myproject 
     238        PythonOption TracUriRoot / 
     239    </Location> 
     240    <Location /login> 
     241        AuthType Basic 
     242        AuthName "MyCompany Trac Server" 
     243        AuthUserFile /var/trac/myproject/.htpasswd 
     244        Require valid-user 
     245    </Location> 
     246</VirtualHost> 
     247}}} 
     248 
     249This does not seem to work in all cases. What you can do if it does not: 
     250 * Try using `<LocationMatch>` instead of `<Location>` 
     251 * <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). 
     252 * Depending on apache's `NameVirtualHost` configuration, you may need to use `<VirtualHost *:80>` instead of `<VirtualHost *>`. 
     253 
     254For a virtual host that supports multiple projects replace "`TracEnv`" /var/trac/myproject with "`TracEnvParentDir`" /var/trac/ 
     255 
     256Note: !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". 
     257 
     258== Troubleshooting == 
     259 
     260In general, if you get server error pages, you can either check the Apache error log, or enable the `PythonDebug` option: 
     261{{{ 
     262#!xml 
     263<Location /projects/myproject> 
     264  ... 
     265  PythonDebug on 
     266</Location> 
     267}}} 
     268 
     269For multiple projects, try restarting the server as well. 
     270 
     271=== Expat-related segmentation faults === #expat 
     272 
     273This problem will most certainly hit you on Unix when using Python 2.4. 
     274In Python 2.4, some version of Expat (an XML parser library written in C) is used,  
     275and if Apache is using another version, this results in segmentation faults. 
     276As Trac 0.11 is using Genshi, which will indirectly use Expat, that problem 
     277can now hit you even if everything was working fine before with Trac 0.10. 
     278 
     279See Graham Dumpleton's detailed [http://www.dscpl.com.au/wiki/ModPython/Articles/ExpatCausingApacheCrash explanation and workarounds] for the issue. 
     280 
     281=== Form submission problems === 
     282 
     283If 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. 
     284 
     285=== Problem with virtual host configuration === 
     286 
     287If 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). 
     288 
     289Using <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. 
     290 
     291=== Problem with zipped egg === 
     292 
     293It's possible that your version of mod_python will not import modules from zipped eggs. If you encounter an `ImportError: No module named trac` in your Apache logs but you think everything is where it should be, this might be your problem. Look in your site-packages directory; if the Trac module appears as a ''file'' rather than a ''directory'', then this might be your problem. To rectify, try installing Trac using the `--always-unzip` option, like this: 
     294 
     295{{{ 
     296easy_install --always-unzip Trac-0.12b1.zip 
     297}}} 
     298 
     299=== Using .htaccess === 
     300 
     301Although 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. 
     302 
     303It 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. :) 
     304 
     305A success story: For me it worked out-of-box, with following trivial config: 
     306{{{ 
     307SetHandler mod_python 
     308PythonInterpreter main_interpreter 
     309PythonHandler trac.web.modpython_frontend  
     310PythonOption TracEnv /system/path/to/this/directory 
     311PythonOption TracUriRoot /path/on/apache 
     312 
     313AuthType Basic 
     314AuthName "ProjectName" 
     315AuthUserFile /path/to/.htpasswd 
     316Require valid-user 
     317}}} 
     318 
     319The `TracUriRoot` is obviously the path you need to enter to the browser to get to the trac (e.g. domain.tld/projects/trac) 
     320 
     321=== Additional .htaccess help === 
     322 
     323If 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: 
     324 
     325{{{ 
     326<IfModule mod_rewrite.c> 
     327  RewriteEngine Off 
     328</IfModule> 
     329}}} 
     330 
     331 
     332=== Win32 Issues === 
     333If 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. 
     334 
     335 
     336=== OS X issues === 
     337 
     338When 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]. 
     339 
     340=== SELinux issues === 
     341 
     342If Trac reports something like: ''Cannot get shared lock on db.lock'' 
     343The security context on the repository may need to be set: 
     344 
     345{{{ 
     346chcon -R -h -t httpd_sys_content_t PATH_TO_REPOSITORY 
     347}}} 
     348 
     349See also [http://subversion.tigris.org/faq.html#reposperms] 
     350 
     351=== FreeBSD issues === 
     352Pay 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. 
     353 
     354If 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. 
     355The best option [http://modpython.org/pipermail/mod_python/2006-September/021983.html seems to be] adding to /usr/local/apache2/bin/ennvars the line  
     356 
     357{{{ 
     358export LD_PRELOAD=/usr/lib/libc_r.so 
     359}}} 
     360 
     361=== Subversion issues === 
     362 
     363If 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.) 
     364 
     365If 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`). 
     366 
     367You 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: 
     368{{{ 
     369PythonInterpreter main_interpreter 
     370}}} 
     371This 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. 
     372 
     373=== Page layout issues === 
     374 
     375If 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: 
     376{{{ 
     377#!xml 
     378Alias /myproject/css "/usr/share/trac/htdocs/css" 
     379<Location /myproject/css> 
     380    SetHandler None 
     381</Location> 
     382}}} 
     383 
     384Note: For the above configuration to have any effect it must be put after the configuration of your project root location, i.e. {{{<Location /myproject />}}}. 
     385 
     386Also, setting `PythonOptimize On` seems to mess up the page headers and footers, in addition to hiding the documentation for macros and plugins (see #Trac8956). Considering how little effect the option has, it is probably a good idea to leave it `Off`. 
     387 
     388=== HTTPS issues === 
     389 
     390If 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: 
     391{{{ 
     392#!xml 
     393<VirtualHost * > 
     394    DocumentRoot /var/www/myproject 
     395    ServerName trac.mycompany.com 
     396    SetEnv HTTPS 1 
     397    .... 
     398</VirtualHost> 
     399}}} 
     400 
     401=== Fedora 7 Issues === 
     402Make sure you install the 'python-sqlite2' package as it seems to be required for TracModPython but not for tracd 
     403 
     404 
     405=== Segmentation fault with php5-mhash or other php5 modules === 
     406You 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] 
     407 
     408Some 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] 
     409 
     410---- 
     411See also:  TracGuide, TracInstall, [wiki:TracModWSGI ModWSGI], [wiki:TracFastCgi FastCGI],  [trac:TracNginxRecipe TracNginxRecipe]