Changes between Initial Version and Version 1 of TracModPython

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04/30/10 16:55:49 (8 years ago)
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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 [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 
     76=== Configuring Authentication === 
     77 
     78Creating password files and configuring authentication works similar to the process for [wiki:TracCgi#AddingAuthentication CGI]: 
     79{{{ 
     80#!xml 
     81<Location /projects/myproject/login> 
     82  AuthType Basic 
     83  AuthName "myproject" 
     84  AuthUserFile /var/trac/myproject/.htpasswd 
     85  Require valid-user 
     86</Location> 
     87}}} 
     88 
     89Configuration for mod_ldap authentication in Apache is a bit tricky (httpd 2.2.x and OpenLDAP: slapd 2.3.19) 
     90 
     911. You need to load the following modules in Apache httpd.conf 
     92{{{ 
     93LoadModule ldap_module modules/mod_ldap.so 
     94LoadModule authnz_ldap_module modules/mod_authnz_ldap.so 
     95}}} 
     96 
     972. Your httpd.conf also needs to look something like: 
     98 
     99{{{ 
     100#!xml 
     101<Location /trac/> 
     102  SetHandler mod_python 
     103  PythonInterpreter main_interpreter 
     104  PythonHandler trac.web.modpython_frontend 
     105  PythonOption TracEnv /home/trac/ 
     106  PythonOption TracUriRoot /trac/ 
     107  Order deny,allow 
     108  Deny from all 
     109  Allow from 192.168.11.0/24 
     110  AuthType Basic 
     111  AuthName "Trac" 
     112  AuthBasicProvider "ldap" 
     113  AuthLDAPURL "ldap://127.0.0.1/dc=example,dc=co,dc=ke?uid?sub?(objectClass=inetOrgPerson)" 
     114  authzldapauthoritative Off 
     115  require valid-user 
     116</Location> 
     117}}} 
     118 
     119Or the LDAP interface to a Microsoft Active Directory: 
     120 
     121{{{ 
     122#!xml 
     123<Location /trac/> 
     124  SetHandler mod_python 
     125  PythonInterpreter main_interpreter 
     126  PythonHandler trac.web.modpython_frontend 
     127  PythonOption TracEnv /home/trac/ 
     128  PythonOption TracUriRoot /trac/ 
     129  Order deny,allow 
     130  Deny from all 
     131  Allow from 192.168.11.0/24 
     132  AuthType Basic 
     133  AuthName "Trac" 
     134  AuthBasicProvider "ldap" 
     135  AuthLDAPURL "ldap://adserver.company.com:3268/DC=company,DC=com?sAMAccountName?sub?(objectClass=user)" 
     136  AuthLDAPBindDN       ldap-auth-user@company.com 
     137  AuthLDAPBindPassword "the_password" 
     138  authzldapauthoritative Off 
     139  # require valid-user 
     140  require ldap-group CN=Trac Users,CN=Users,DC=company,DC=com 
     141</Location> 
     142}}} 
     143 
     144Note 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. 
     145 
     146Note 2: Active Directory requires an authenticating user/password to access records (AuthLDAPBindDN and AuthLDAPBindPassword). 
     147 
     148Note 3: The directive "require ldap-group ..."  specifies an AD group whose members are allowed access. 
     149 
     150 
     151 
     152=== Setting the !PythonPath === 
     153 
     154If 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: 
     155{{{ 
     156#!xml 
     157<Location /projects/myproject> 
     158  ... 
     159  PythonPath "sys.path + ['/path/to/trac']" 
     160  ... 
     161</Location> 
     162}}} 
     163 
     164Be careful about using the !PythonPath directive, and ''not'' `SetEnv PYTHONPATH`, as the latter won't work. 
     165 
     166== Setting up multiple projects == 
     167 
     168The Trac mod_python handler supports a configuration option similar to Subversion's `SvnParentPath`, called `TracEnvParentDir`: 
     169{{{ 
     170#!xml 
     171<Location /projects> 
     172  SetHandler mod_python 
     173  PythonInterpreter main_interpreter 
     174  PythonHandler trac.web.modpython_frontend  
     175  PythonOption TracEnvParentDir /var/trac 
     176  PythonOption TracUriRoot /projects 
     177</Location> 
     178}}} 
     179 
     180When 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. 
     181 
     182If you don't want to have the subdirectory listing as your projects home page you can use a 
     183{{{ 
     184#!xml 
     185<LocationMatch "/.+/"> 
     186}}} 
     187 
     188This 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. 
     189 
     190You can also use the same authentication realm for all of the projects using a `<LocationMatch>` directive: 
     191{{{ 
     192#!xml 
     193<LocationMatch "/projects/[^/]+/login"> 
     194  AuthType Basic 
     195  AuthName "Trac" 
     196  AuthUserFile /var/trac/.htpasswd 
     197  Require valid-user 
     198</LocationMatch> 
     199}}} 
     200 
     201== Virtual Host Configuration == 
     202 
     203Below is the sample configuration required to set up your trac as a virtual server (i.e. when you access it at the URLs like 
     204!http://trac.mycompany.com): 
     205 
     206{{{ 
     207#!xml 
     208<VirtualHost * > 
     209    DocumentRoot /var/www/myproject 
     210    ServerName trac.mycompany.com 
     211    <Location /> 
     212        SetHandler mod_python 
     213        PythonInterpreter main_interpreter 
     214        PythonHandler trac.web.modpython_frontend 
     215        PythonOption TracEnv /var/trac/myproject 
     216        PythonOption TracUriRoot / 
     217    </Location> 
     218    <Location /login> 
     219        AuthType Basic 
     220        AuthName "MyCompany Trac Server" 
     221        AuthUserFile /var/trac/myproject/.htpasswd 
     222        Require valid-user 
     223    </Location> 
     224</VirtualHost> 
     225}}} 
     226 
     227This does not seem to work in all cases. What you can do if it does not: 
     228 * Try using `<LocationMatch>` instead of `<Location>` 
     229 * <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). 
     230 
     231For a virtual host that supports multiple projects replace "`TracEnv`" /var/trac/myproject with "`TracEnvParentDir`" /var/trac/ 
     232 
     233Note: !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". 
     234 
     235== Troubleshooting == 
     236 
     237In general, if you get server error pages, you can either check the Apache error log, or enable the `PythonDebug` option: 
     238{{{ 
     239#!xml 
     240<Location /projects/myproject> 
     241  ... 
     242  PythonDebug on 
     243</Location> 
     244}}} 
     245 
     246For multiple projects, try restarting the server as well. 
     247 
     248=== Expat-related segmentation faults === #expat 
     249 
     250This problem will most certainly hit you on Unix when using Python 2.4. 
     251In Python 2.4, some version of Expat (an XML parser library written in C) is used,  
     252and if Apache is using another version, this results in segmentation faults. 
     253As Trac 0.11 is using Genshi, which will indirectly use Expat, that problem 
     254can now hit you even if everything was working fine before with Trac 0.10. 
     255 
     256See Graham Dumpleton's detailed [http://www.dscpl.com.au/wiki/ModPython/Articles/ExpatCausingApacheCrash explanation and workarounds] for the issue. 
     257 
     258=== Form submission problems === 
     259 
     260If 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. 
     261 
     262=== Problem with virtual host configuration === 
     263 
     264If 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). 
     265 
     266Using <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. 
     267 
     268=== Using .htaccess === 
     269 
     270Although 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. 
     271 
     272It 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. :) 
     273 
     274A success story: For me it worked out-of-box, with following trivial config: 
     275{{{ 
     276SetHandler mod_python 
     277PythonInterpreter main_interpreter 
     278PythonHandler trac.web.modpython_frontend  
     279PythonOption TracEnv /system/path/to/this/directory 
     280PythonOption TracUriRoot /path/on/apache 
     281 
     282AuthType Basic 
     283AuthName "ProjectName" 
     284AuthUserFile /path/to/.htpasswd 
     285Require valid-user 
     286}}} 
     287 
     288The TracUriRoot is obviously the path you need to enter to the browser to get to the trac (e.g. domain.tld/projects/trac) 
     289 
     290=== Additional .htaccess help === 
     291 
     292If 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: 
     293 
     294{{{ 
     295<IfModule mod_rewrite.c> 
     296  RewriteEngine Off 
     297</IfModule> 
     298}}} 
     299 
     300 
     301=== Win32 Issues === 
     302If 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. 
     303 
     304 
     305=== OS X issues === 
     306 
     307When 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]. 
     308 
     309=== SELinux issues === 
     310 
     311If Trac reports something like: ''Cannot get shared lock on db.lock'' 
     312The security context on the repository may need to be set: 
     313 
     314{{{ 
     315chcon -R -h -t httpd_sys_content_t PATH_TO_REPOSITORY 
     316}}} 
     317 
     318See also [[http://subversion.tigris.org/faq.html#reposperms]] 
     319 
     320=== FreeBSD issues === 
     321Pay 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. 
     322 
     323If 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. 
     324The best option [[http://modpython.org/pipermail/mod_python/2006-September/021983.html seems to be]] adding to /usr/local/apache2/bin/ennvars the line  
     325 
     326{{{ 
     327export LD_PRELOAD=/usr/lib/libc_r.so 
     328}}} 
     329 
     330=== Subversion issues === 
     331 
     332If 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.) 
     333 
     334If 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`). 
     335 
     336You 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 #3371, in order to force the use of the main interpreter: 
     337{{{ 
     338PythonInterpreter main_interpreter 
     339}}} 
     340This is anyway the recommended workaround for other well-known issues seen when using the Python bindings for Subversion within mod_python (#2611, #3455). See in particular Graham Dumpleton's comment in [comment:ticket:3455:9 #3455] explaining the issue. 
     341 
     342=== Page layout issues === 
     343 
     344If 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: 
     345{{{ 
     346#!xml 
     347Alias /myproject/css "/usr/share/trac/htdocs/css" 
     348<Location /myproject/css> 
     349    SetHandler None 
     350</Location> 
     351}}} 
     352 
     353Note: For the above configuration to have any effect it must be put after the configuration of your project root location, i.e. {{{<Location /myproject />}}}. 
     354 
     355=== HTTPS issues === 
     356 
     357If 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: 
     358{{{ 
     359#!xml 
     360<VirtualHost * > 
     361    DocumentRoot /var/www/myproject 
     362    ServerName trac.mycompany.com 
     363    SetEnv HTTPS 1 
     364    .... 
     365</VirtualHost> 
     366}}} 
     367 
     368=== Fedora 7 Issues === 
     369Make sure you install the 'python-sqlite2' package as it seems to be required for TracModPython but not for tracd 
     370 
     371 
     372=== Segmentation fault with php5-mhash or other php5 modules === 
     373You 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]] 
     374 
     375Some 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]] 
     376 
     377---- 
     378See also:  TracGuide, TracInstall, [wiki:TracModWSGI ModWSGI], [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]