Changes between Version 7 and Version 8 of TracModPython


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Timestamp:
03/24/15 23:16:50 (2 years ago)
Author:
trac
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  • TracModPython

    v7 v8  
    1 = Trac and mod_python =
     1= Trac and mod_python
    22[[TracGuideToc]]
    33
     4Mod_python is an [https://httpd.apache.org/ Apache] module that embeds the Python interpreter within the server, so that web-based applications in Python will run many times faster than traditional CGI and will have the ability to retain database connections.
    45Trac 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.
    56
    6 {{{#!div class="important"
    7 ** A Word of Warning **
    8 
    9 As 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.
    10 }}}
    11 
    12 
    13 These 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], but you'll be totally on your own.
     7These instructions are for Apache 2. If you are using Apache 1.3, you may have some luck with [trac:wiki:TracModPython2.7 TracModPython2.7], but that is a deprecated setup.
    148
    159[[PageOutline(2-3,Overview,inline)]]
     
    2418''Note: The exact path to the module depends on how the HTTPD installation is laid out.''
    2519
    26 On Debian using apt-get
     20On Debian using apt-get:
    2721{{{
    2822apt-get install libapache2-mod-python libapache2-mod-python-doc
    2923}}}
    30 (Still on Debian) after you have installed mod_python, you must enable the modules in apache2 (equivalent of the above Load Module directive):
     24Still on Debian, after you have installed mod_python, you must enable the modules in apache2, equivalent to the above Load Module directive:
    3125{{{
    3226a2enmod python
     
    3630yum install mod_python
    3731}}}
    38 You 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+.
     32You 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+.
    3933{{{
    4034#!xml
     
    6256}}}
    6357
    64 The 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.
    65 
    66 The options available are
     58The 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.
     59
     60The options available are:
    6761{{{
    6862    # For a single project
     
    8579}}}
    8680
    87 === Python Egg Cache ===
    88 
    89 Compressed 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:
     81=== Python Egg Cache
     82
     83Compressed 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:
    9084{{{
    9185PythonOption PYTHON_EGG_CACHE /var/trac/myprojects/egg-cache
     
    9488or you can uncompress the Genshi egg to resolve problems extracting from it.
    9589
    96 === Configuring Authentication ===
     90=== Configuring Authentication
    9791
    9892See corresponding section in the [wiki:TracModWSGI#ConfiguringAuthentication] page.
    9993
    100 
    10194== Advanced Configuration
    10295
    103 === Setting the Python Egg Cache ===
     96=== Setting the Python Egg Cache
    10497
    10598If 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.
     
    114107}}}
    115108
    116 
    117 === Setting the !PythonPath ===
     109=== Setting the !PythonPath
    118110
    119111If 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:
     
    129121Be careful about using the !PythonPath directive, and ''not'' `SetEnv PYTHONPATH`, as the latter won't work.
    130122
    131 === Setting up multiple projects ===
     123=== Setting up multiple projects
    132124
    133125The Trac mod_python handler supports a configuration option similar to Subversion's `SvnParentPath`, called `TracEnvParentDir`:
     
    164156}}}
    165157
    166 === Virtual Host Configuration ===
    167 
    168 Below is the sample configuration required to set up your trac as a virtual server (i.e. when you access it at the URLs like
    169 !http://trac.mycompany.com):
     158=== Virtual Host Configuration
     159
     160Below is the sample configuration required to set up your trac as a virtual server, ie when you access it at the URLs like
     161!http://trac.mycompany.com:
    170162
    171163{{{
     
    192184This does not seem to work in all cases. What you can do if it does not:
    193185 * Try using `<LocationMatch>` instead of `<Location>`
    194  * <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).
     186 * <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, ie /web/ and /web/login instead of / and /login.
    195187 * Depending on apache's `NameVirtualHost` configuration, you may need to use `<VirtualHost *:80>` instead of `<VirtualHost *>`.
    196188
     
    199191Note: !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".
    200192
    201 == Troubleshooting ==
     193== Troubleshooting
    202194
    203195In general, if you get server error pages, you can either check the Apache error log, or enable the `PythonDebug` option:
     
    212204For multiple projects, try restarting the server as well.
    213205
    214 === Login Not Working ===
     206=== Login Not Working
     207
    215208If you've used `<Location />` directive, it will override any other directives, as well as `<Location /login>`.
    216209The workaround is to use negation expression as follows (for multi project setups):
     
    247240
    248241This problem will most certainly hit you on Unix when using Python 2.4.
    249 In Python 2.4, some version of Expat (an XML parser library written in C) is used,
    250 and if Apache is using another version, this results in segmentation faults.
    251 As Trac 0.11 is using Genshi, which will indirectly use Expat, that problem
    252 can now hit you even if everything was working fine before with Trac 0.10.
    253 
    254 See Graham Dumpleton's detailed [http://www.dscpl.com.au/wiki/ModPython/Articles/ExpatCausingApacheCrash explanation and workarounds] for the issue.
    255 
    256 === Form submission problems ===
     242In Python 2.4, some version of [http://expat.sourceforge.net/ Expat] (an XML parser library written in C) is used and if Apache is using another version, this results in segmentation faults.
     243As Trac 0.11 is using Genshi, which will indirectly use Expat, that problem can now hit you even if everything was working fine before with Trac 0.10. This problem has not been reported for Python 2.5+, so best to upgrade.
     244
     245=== Form submission problems
    257246
    258247If 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.
    259248
    260 === Problem with virtual host configuration ===
    261 
    262 If 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).
    263 
    264 Using <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.
    265 
    266 === Problem with zipped egg ===
     249=== Problem with virtual host configuration
     250
     251If 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.
     252
     253Using <Location /> together with `SetHandler` resulted in having everything handled by mod_python, which leads to not being able to download any CSS or images/icons. Use <Location /trac> `SetHandler None` </Location> to circumvent the problem, though this may not be the most elegant solution.
     254
     255=== Problem with zipped egg
    267256
    268257It'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:
     
    272261}}}
    273262
    274 === Using .htaccess ===
     263=== Using .htaccess
    275264
    276265Although 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.
    277266
    278 It 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. :)
    279 
    280 A success story: For me it worked out-of-box, with following trivial config:
     267It 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.
     268
     269This also works out-of-box, with following trivial config:
    281270{{{#!xml
    282271SetHandler mod_python
     
    292281}}}
    293282
    294 The `TracUriRoot` is obviously the path you need to enter to the browser to get to the trac (e.g. domain.tld/projects/trac)
    295 
    296 === Additional .htaccess help ===
    297 
    298 If 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:
     283The `TracUriRoot` is obviously the path you need to enter to the browser to get to Trac, eg domain.tld/projects/trac.
     284
     285=== Additional .htaccess help
     286
     287If 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:
    299288
    300289{{{
     
    305294
    306295=== Platform specific issues
    307 ==== Win32 Issues ====
     296==== Win32 Issues
     297
    308298If 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.
    309299
    310 
    311 ==== OS X issues ====
    312 
    313 When 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].
    314 
    315 ==== SELinux issues ====
     300==== OS X issues
     301
     302When 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, so please upgrade.
     303
     304==== SELinux issues
    316305
    317306If Trac reports something like: ''Cannot get shared lock on db.lock''
     
    322311}}}
    323312
    324 See also [http://subversion.tigris.org/faq.html#reposperms]
    325 
    326 ==== FreeBSD issues ====
    327 Pay 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.
    328 
    329 If 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.
    330 The best option [http://modpython.org/pipermail/mod_python/2006-September/021983.html seems to be] adding to /usr/local/apache2/bin/ennvars the line
     313See also [http://subversion.apache.org/faq.html#reposperms How do I set repository permissions correctly?]
     314
     315==== FreeBSD issues
     316
     317The FreeBSD ports have both the new and old versions of mod_python and SQLite, 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.
     318
     319If you compiled and installed apache2, threads are not automatically supported on FreeBSD. You could force thread support when running `./configure` for Apache, using `--enable-threads`, but this isn´t recommended.
     320The best option [http://modpython.org/pipermail/mod_python/2006-September/021983.html seems to be] adding to /usr/local/apache2/bin/ennvars the line:
    331321
    332322{{{
     
    334324}}}
    335325
    336 
    337 ==== Fedora 7 Issues ====
    338 Make sure you install the 'python-sqlite2' package as it seems to be required for TracModPython but not for tracd
    339 
    340 
    341 === Subversion issues ===
    342 
    343 If 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.)
    344 
    345 If 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`).
    346 
    347 You 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:
     326==== Fedora 7 Issues
     327
     328Make sure you install the 'python-sqlite2' package as it seems to be required for TracModPython but not for tracd.
     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 and 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. Version 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:
    348337{{{
    349338PythonInterpreter main_interpreter
    350339}}}
     340
    351341This 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.
    352342
    353 === Page layout issues ===
    354 
    355 If 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:
     343=== Page layout issues
     344
     345If 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:
    356346{{{
    357347#!xml
     
    364354Note: For the above configuration to have any effect it must be put after the configuration of your project root location, i.e. {{{<Location /myproject />}}}.
    365355
    366 Also, 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`.
    367 
    368 === HTTPS issues ===
     356Also, 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, leave it `Off`.
     357
     358=== HTTPS issues
    369359
    370360If 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:
     
    379369}}}
    380370
    381 
    382 === Segmentation fault with php5-mhash or other php5 modules ===
    383 You 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]
    384 
    385 Some 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]
     371=== Segmentation fault with php5-mhash or other php5 modules
     372
     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 [http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=411487 Debian bug report].
     374
     375Some people also have troubles when using php5 compiled with its own 3rd party libraries instead of system libraries. Check [http://www.djangoproject.com/documentation/modpython/#if-you-get-a-segmentation-fault Django segmentation fault].
    386376
    387377----
    388 See also:  TracGuide, TracInstall, [wiki:TracModWSGI ModWSGI], [wiki:TracFastCgi FastCGI],  [trac:TracNginxRecipe TracNginxRecipe]
     378See also: TracGuide, TracInstall, [wiki:TracModWSGI ModWSGI], [wiki:TracFastCgi FastCGI], [trac:TracNginxRecipe]