Changes between Version 1 and Version 2 of TracModPython


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Timestamp:
01/28/2011 02:52:13 PM (5 years ago)
Author:
trac
Comment:

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  • TracModPython

    v1 v2  
    11= Trac and mod_python =
    2 
    3 Trac 0.7.1 and later supports [http://www.modpython.org/ mod_python], which speeds up Trac's response times considerably and permits use of many Apache features not possible with tracd/mod_proxy.
     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].
    47
    58== Simple configuration ==
    69
    7 Here's a typical Trac CGI/Apache setup:
    8 
    9 {{{
    10 ScriptAlias /projects/myproject /path/to/python/share/trac/cgi-bin/trac.cgi
    11 <Location /projects/myproject>
    12    SetEnv TRAC_ENV /var/trac/myproject
    13 </Location>
    14 }}}
    15 
    16 The equivalent mod_python setup is:
    17 
    18 {{{
     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
    1942<Location /projects/myproject>
    2043   SetHandler mod_python
    21    PythonHandler trac.ModPythonHandler
    22    PythonOption TracUriRoot "/projects/myproject"
     44   PythonInterpreter main_interpreter
     45   PythonHandler trac.web.modpython_frontend
    2346   PythonOption TracEnv /var/trac/myproject
    24 </Location>
    25 }}}
    26 
    27 Note that the option ''TracUriRoot'' may or may not be necessary in your setup. Try without first, and if the URLs produced by Trac look wrong, add the ''TracUriRoot'' option.
     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.
    28179
    29180== Setting up multiple projects ==
    30181
    31 The Trac mod_python handler handler supports a configuration option similar to Subversion's {{{SvnParentPath}}}, called {{{TracEnvParentDir}}}:
    32 
    33 {{{
     182The Trac mod_python handler supports a configuration option similar to Subversion's `SvnParentPath`, called `TracEnvParentDir`:
     183{{{
     184#!xml
    34185<Location /projects>
    35186  SetHandler mod_python
    36   PythonHandler trac.ModPythonHandler
     187  PythonInterpreter main_interpreter
     188  PythonHandler trac.web.modpython_frontend
     189  PythonOption TracEnvParentDir /var/trac
    37190  PythonOption TracUriRoot /projects
    38   PythonOption TracEnvParentDir "/var/trac"
    39 </LocationMatch>
    40 }}}
    41 
    42 When you request the {{{/projects}}} URL, you will get a (currently very simple) listing of all subdirectories of the directory you set as {{{TracEnvParentDir}}}. Selecting any project in the list will bring you to the corresponding Trac instance. You should make sure that the configured directory only contains Trac environment directories that match the currently installed Trac version, because that is not checked prior the the generation of the project list.
    43 
    44 
    45 === Adding authentication ===
    46 
    47 Adding authentication is straightforward in both cases. For example:
    48 
    49 {{{
    50 <LocationMatch /projects/[[:alnum:]]+/login>
     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">
    51208  AuthType Basic
    52209  AuthName "Trac"
    53   AuthUserFile /var/www/passwd
     210  AuthUserFile /var/trac/.htpasswd
    54211  Require valid-user
    55212</LocationMatch>
    56213}}}
    57214
     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=== Problem with zipped egg ===
     284
     285It'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:
     286
     287{{{
     288easy_install --always-unzip Trac-0.12b1.zip
     289}}}
     290
     291=== Using .htaccess ===
     292
     293Although 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.
     294
     295It 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. :)
     296
     297A success story: For me it worked out-of-box, with following trivial config:
     298{{{
     299SetHandler mod_python
     300PythonInterpreter main_interpreter
     301PythonHandler trac.web.modpython_frontend
     302PythonOption TracEnv /system/path/to/this/directory
     303PythonOption TracUriRoot /path/on/apache
     304
     305AuthType Basic
     306AuthName "ProjectName"
     307AuthUserFile /path/to/.htpasswd
     308Require valid-user
     309}}}
     310
     311The `TracUriRoot` is obviously the path you need to enter to the browser to get to the trac (e.g. domain.tld/projects/trac)
     312
     313=== Additional .htaccess help ===
     314
     315If 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:
     316
     317{{{
     318<IfModule mod_rewrite.c>
     319  RewriteEngine Off
     320</IfModule>
     321}}}
     322
     323
    58324=== Win32 Issues ===
    59 
    60 If you run trac with mod_python on Windows, attachments will not work.
    61 
    62 There is a (simple) workaround for this which is to apply the patch attached to
    63 ticket [http://projects.edgewall.com/trac/ticket/554 #554].
    64 
     325If 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.
     326
     327
     328=== OS X issues ===
     329
     330When 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].
     331
     332=== SELinux issues ===
     333
     334If Trac reports something like: ''Cannot get shared lock on db.lock''
     335The security context on the repository may need to be set:
     336
     337{{{
     338chcon -R -h -t httpd_sys_content_t PATH_TO_REPOSITORY
     339}}}
     340
     341See also [http://subversion.tigris.org/faq.html#reposperms]
     342
     343=== FreeBSD issues ===
     344Pay 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.
     345
     346If 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.
     347The best option [http://modpython.org/pipermail/mod_python/2006-September/021983.html seems to be] adding to /usr/local/apache2/bin/ennvars the line
     348
     349{{{
     350export LD_PRELOAD=/usr/lib/libc_r.so
     351}}}
     352
     353=== Subversion issues ===
     354
     355If 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.)
     356
     357If 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`).
     358
     359You 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:
     360{{{
     361PythonInterpreter main_interpreter
     362}}}
     363This 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.
     364
     365=== Page layout issues ===
     366
     367If 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:
     368{{{
     369#!xml
     370Alias /myproject/css "/usr/share/trac/htdocs/css"
     371<Location /myproject/css>
     372    SetHandler None
     373</Location>
     374}}}
     375
     376Note: For the above configuration to have any effect it must be put after the configuration of your project root location, i.e. {{{<Location /myproject />}}}.
     377
     378Also, 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`.
     379
     380=== HTTPS issues ===
     381
     382If 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:
     383{{{
     384#!xml
     385<VirtualHost * >
     386    DocumentRoot /var/www/myproject
     387    ServerName trac.mycompany.com
     388    SetEnv HTTPS 1
     389    ....
     390</VirtualHost>
     391}}}
     392
     393=== Fedora 7 Issues ===
     394Make sure you install the 'python-sqlite2' package as it seems to be required for TracModPython but not for tracd
     395
     396
     397=== Segmentation fault with php5-mhash or other php5 modules ===
     398You 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]
     399
     400Some 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]
    65401
    66402----
    67 See also TracGuide, TracInstall, TracMultipleProjects
     403See also:  TracGuide, TracInstall, [wiki:TracModWSGI ModWSGI], [wiki:TracFastCgi FastCGI],  [trac:TracNginxRecipe TracNginxRecipe]
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