Changes between Version 5 and Version 6 of TracModWSGI


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Timestamp:
Dec 14, 2014, 5:16:20 PM (10 years ago)
Author:
trac
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  • TracModWSGI

    v5 v6  
    11= Trac and mod_wsgi =
    22
     3'''Important note:''' ''Please use either version 1.6, 2.4 or later of `mod_wsgi`. Versions prior to 2.4 in the 2.X branch have problems with some Apache configurations that use WSGI file wrapper extension. This extension is used in Trac to serve up attachments and static media files such as style sheets. If you are affected by this problem attachments will appear to be empty and formatting of HTML pages will appear not to work due to style sheet files not loading properly. See mod_wsgi tickets [http://code.google.com/p/modwsgi/issues/detail?id=100 #100] and [http://code.google.com/p/modwsgi/issues/detail?id=132 #132].''
    34
    4 [http://code.google.com/p/modwsgi/ mod_wsgi] is an Apache module for running WSGI-compatible Python applications directly on top of the Apache webserver. The mod_wsgi adapter is written completely in C and provides very good performances.
     5[http://code.google.com/p/modwsgi/ mod_wsgi] is an Apache module for running WSGI-compatible Python applications directly on top of Apache. The mod_wsgi adapter is written completely in C and provides significantly better performance than using existing WSGI adapters for mod_python or CGI.
    56
    6 [[PageOutline(2-3,Overview,inline)]]
     7Trac can be run on top of mod_wsgi with the help of the following application script, which is just a Python file, though usually saved with a .wsgi extension). This file can be created using '''trac-admin <env> deploy <dir>''' command which automatically substitutes required paths.
    78
    8 == The `trac.wsgi` script
    9 
    10 Trac can be run on top of mod_wsgi with the help of the following application script, which is just a Python file, though usually saved with a `.wsgi` extension).
    11 
    12 === A very basic script
    13 In its simplest form, the script could be:
    14 
    15 {{{#!python
     9{{{
     10#!python
    1611import os
    1712
    … …  
    2520The `TRAC_ENV` variable should naturally be the directory for your Trac environment (if you have several Trac environments in a directory, you can also use `TRAC_ENV_PARENT_DIR` instead), while the `PYTHON_EGG_CACHE` should be a directory where Python can temporarily extract Python eggs.
    2621
    27 === A more elaborate script
     22'''Important note:''' If you're using multiple `.wsgi` files (for example one per Trac environment) you must ''not'' use `os.environ['TRAC_ENV']` to set the path to the Trac environment. Using this method may lead to Trac delivering the content of another Trac environment. (The variable may be filled with the path of a previously viewed Trac environment.) To solve this problem, use the following `.wsgi` file instead:
    2823
    29 If you're using multiple `.wsgi` files (for example one per Trac environment) you must ''not'' use `os.environ['TRAC_ENV']` to set the path to the Trac environment. Using this method may lead to Trac delivering the content of another Trac environment, as the variable may be filled with the path of a previously viewed Trac environment.
    30 
    31 To solve this problem, use the following `.wsgi` file instead:
    32 {{{#!python
     24{{{
     25#!python
    3326import os
    3427
    … …  
    4134}}}
    4235
    43 For clarity, you should give this file a `.wsgi` extension. You should probably put the file in its own directory, since you will expose it to Apache.
     36For clarity, you should give this file a `.wsgi` extension. You should probably put the file in it's own directory, since you will open up its directory to Apache. You can create a .wsgi files which handles all this for you by running the TracAdmin command `deploy`.
    4437
    45 If you have installed Trac and eggs in a path different from the standard one you should add that path by adding the following code at the top of the wsgi script:
     38If you have installed trac and eggs in a path different from the standard one you should add that path by adding the following code on top of the wsgi script:
    4639
    47 {{{#!python
     40{{{
     41#!python
    4842import site
    4943site.addsitedir('/usr/local/trac/lib/python2.4/site-packages')
    5044}}}
    5145
    52 Change it according to the path you installed the Trac libs at.
     46Change it according to the path you installed the trac libs at.
    5347
    54 === Recommended `trac.wsgi` script
    55 
    56 A somewhat robust and generic version of this file can be created using the `trac-admin <env> deploy <dir>` command which automatically substitutes the required paths (see TracInstall#cgi-bin).
    57 
    58 
    59 == Mapping requests to the script
    60 
    61 After you've done preparing your .wsgi script, add the following to your Apache configuration file (`httpd.conf` for example).
     48After you've done preparing your wsgi-script, add the following to your httpd.conf.
    6249
    6350{{{
    … …  
    7158}}}
    7259
    73 Here, the script is in a subdirectory of the Trac environment.
     60Here, the script is in a subdirectory of the Trac environment. In order to let Apache run the script, access to the directory in which the script resides is opened up to all of Apache. Additionally, the {{{WSGIApplicationGroup}}} directive ensures that Trac is always run in the first Python interpreter created by mod_wsgi; this is necessary because the Subversion Python bindings, which are used by Trac, don't always work in other subinterpreters and may cause requests to hang or cause Apache to crash as a result. After adding this configuration, restart Apache, and then it should work.
    7461
    75 If you followed the directions [http://trac.edgewall.org/wiki/TracInstall#cgi-bin Generating the Trac cgi-bin directory], your Apache configuration file should look like following:
     62To test the setup of Apache, mod_wsgi and Python itself (ie. without involving Trac and dependencies), this simple wsgi application can be used to make sure that requests gets served (use as only content in your .wsgi script):
    7663
    7764{{{
    78 WSGIScriptAlias /trac /usr/share/trac/cgi-bin/trac.wsgi
    79 
    80 <Directory /usr/share/trac/cgi-bin>
    81     WSGIApplicationGroup %{GLOBAL}
    82     Order deny,allow
    83     Allow from all
    84 </Directory>
    85 }}}
    86 
    87 In order to let Apache run the script, access to the directory in which the script resides is opened up to all of Apache. Additionally, the `WSGIApplicationGroup` directive ensures that Trac is always run in the first Python interpreter created by mod_wsgi; this is necessary because the Subversion Python bindings, which are used by Trac, don't always work in other sub-interpreters and may cause requests to hang or cause Apache to crash as a result. After adding this configuration, restart Apache, and then it should work.
    88 
    89 To test the setup of Apache, mod_wsgi and Python itself (ie. without involving Trac and dependencies), this simple wsgi application can be used to make sure that requests gets served (use as only content in your `.wsgi` script):
    90 
    91 {{{#!python
    9265def application(environ, start_response):
    9366        start_response('200 OK',[('Content-type','text/html')])
    … …  
    9568}}}
    9669
    97 For more information about using the mod_wsgi specific directives, see the [http://code.google.com/p/modwsgi/wiki/ mod_wsgi's wiki] and more specifically the [http://code.google.com/p/modwsgi/wiki/IntegrationWithTrac IntegrationWithTrac] page.
     70See also the mod_wsgi [http://code.google.com/p/modwsgi/wiki/IntegrationWithTrac installation instructions] for Trac.
    9871
    99 
    100 == Configuring Authentication
    101 
    102 We describe in the the following sections different methods for setting up authentication.
    103 
    104 See also [http://httpd.apache.org/docs/2.2/howto/auth.html Authentication, Authorization and Access Control] in the Apache guide.
    105 
    106 === Using Basic Authentication ===
    107 
    108 The simplest way to enable authentication with Apache is to create a password file. Use the `htpasswd` program to create the password file:
    109 {{{
    110 $ htpasswd -c /somewhere/trac.htpasswd admin
    111 New password: <type password>
    112 Re-type new password: <type password again>
    113 Adding password for user admin
    114 }}}
    115 
    116 After the first user, you dont need the "-c" option anymore:
    117 {{{
    118 $ htpasswd /somewhere/trac.htpasswd john
    119 New password: <type password>
    120 Re-type new password: <type password again>
    121 Adding password for user john
    122 }}}
    123 
    124   ''See the man page for `htpasswd` for full documentation.''
    125 
    126 After you've created the users, you can set their permissions using TracPermissions.
    127 
    128 Now, you'll need to enable authentication against the password file in the Apache configuration:
    129 {{{
    130 <Location "/trac/login">
    131   AuthType Basic
    132   AuthName "Trac"
    133   AuthUserFile /somewhere/trac.htpasswd
    134   Require valid-user
    135 </Location>
    136 }}}
    137 
    138 If you're hosting multiple projects you can use the same password file for all of them:
    139 {{{
    140 <LocationMatch "/trac/[^/]+/login">
    141   AuthType Basic
    142   AuthName "Trac"
    143   AuthUserFile /somewhere/trac.htpasswd
    144   Require valid-user
    145 </LocationMatch>
    146 }}}
    147 Note that neither a file nor a directory named 'login' needs to exist.[[BR]]
    148 See also the [http://httpd.apache.org/docs/2.2/mod/mod_auth_basic.html mod_auth_basic] documentation.
    149 
    150 === Using Digest Authentication ===
    151 
    152 For better security, it is recommended that you either enable SSL or at least use the “digest” authentication scheme instead of “Basic”.
    153 
    154 You'll have to create your `.htpasswd` file with the `htdigest` command instead of `htpasswd`, as follows:
    155 {{{
    156 # htdigest -c /somewhere/trac.htpasswd trac admin
    157 }}}
    158 
    159 The "trac" parameter above is the "realm", and will have to be reused in the Apache configuration in the !AuthName directive:
    160 
    161 {{{
    162 <Location "/trac/login">
    163 
    164     AuthType Digest
    165     AuthName "trac"
    166     AuthDigestDomain /trac
    167     AuthUserFile /somewhere/trac.htpasswd
    168     Require valid-user
    169 </Location>
    170 }}}
    171 
    172 For multiple environments, you can use the same `LocationMatch` as described with the previous method.
    173 
    174 Don't forget to activate the mod_auth_digest. For example, on a Debian 4.0r1 (etch) system:
    175 {{{
    176     LoadModule auth_digest_module /usr/lib/apache2/modules/mod_auth_digest.so
    177 }}}
    178 
    179 
    180 See also the [http://httpd.apache.org/docs/2.2/mod/mod_auth_digest.html mod_auth_digest] documentation.
    181 
    182 === Using LDAP Authentication
    183 
    184 Configuration for [http://httpd.apache.org/docs/2.2/mod/mod_ldap.html mod_ldap] authentication in Apache is a bit tricky (httpd 2.2.x and OpenLDAP: slapd 2.3.19)
    185 
    186 1. You need to load the following modules in Apache httpd.conf
    187 {{{
    188 LoadModule ldap_module modules/mod_ldap.so
    189 LoadModule authnz_ldap_module modules/mod_authnz_ldap.so
    190 }}}
    191 
    192 2. Your httpd.conf also needs to look something like:
    193 
    194 {{{
    195 <Location /trac/>
    196   # (if you're using it, mod_python specific settings go here)
    197   Order deny,allow
    198   Deny from all
    199   Allow from 192.168.11.0/24
    200   AuthType Basic
    201   AuthName "Trac"
    202   AuthBasicProvider "ldap"
    203   AuthLDAPURL "ldap://127.0.0.1/dc=example,dc=co,dc=ke?uid?sub?(objectClass=inetOrgPerson)"
    204   authzldapauthoritative Off
    205   Require valid-user
    206 </Location>
    207 }}}
    208 
    209 
    210 3. You can use the LDAP interface as a way to authenticate to a Microsoft Active Directory:
    211 
    212 
    213 Use the following as your LDAP URL:
    214 {{{
    215     AuthLDAPURL "ldap://directory.example.com:3268/DC=example,DC=com?sAMAccountName?sub?(objectClass=user)"
    216 }}}
    217 
    218 You will also need to provide an account for Apache to use when checking
    219 credentials. As this password will be listed in plaintext in the
    220 config, you should be sure to use an account specifically for this task:
    221 {{{
    222     AuthLDAPBindDN ldap-auth-user@example.com
    223     AuthLDAPBindPassword "password"
    224 }}}
    225 
    226 The whole section looks like:
    227 {{{
    228 <Location /trac/>
    229   # (if you're using it, mod_python specific settings go here)
    230   Order deny,allow
    231   Deny from all
    232   Allow from 192.168.11.0/24
    233   AuthType Basic
    234   AuthName "Trac"
    235   AuthBasicProvider "ldap"
    236   AuthLDAPURL "ldap://adserver.company.com:3268/DC=company,DC=com?sAMAccountName?sub?(objectClass=user)"
    237   AuthLDAPBindDN       ldap-auth-user@company.com
    238   AuthLDAPBindPassword "the_password"
    239   authzldapauthoritative Off
    240   # require valid-user
    241   require ldap-group CN=Trac Users,CN=Users,DC=company,DC=com
    242 </Location>
    243 }}}
    244 
    245 Note 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.
    246 
    247 Note 2: You can also require the user be a member of a certain LDAP group, instead of
    248 just having a valid login:
    249 {{{
    250     Require ldap-group CN=Trac Users,CN=Users,DC=example,DC=com
    251 }}}
    252 
    253 See also:
    254   - [http://httpd.apache.org/docs/2.2/mod/mod_authnz_ldap.html mod_authnz_ldap], documentation for mod_authnz_ldap
    255    
    256  - [http://httpd.apache.org/docs/2.2/mod/mod_ldap.html mod_ldap], documentation for mod_ldap, which provides connection pooling and a shared cache.
    257  - [http://trac-hacks.org/wiki/LdapPlugin TracHacks:LdapPlugin] for storing TracPermissions in LDAP.
    258 
    259 === Using SSPI Authentication
    260 
    261 If you are using Apache on Windows, you can use mod_auth_sspi to provide
    262 single-sign-on. Download the module from the !SourceForge [http://sourceforge.net/projects/mod-auth-sspi/ mod-auth-sspi project] and then add the
    263 following to your !VirtualHost:
    264 {{{
    265     <Location /trac/login>
    266         AuthType SSPI
    267         AuthName "Trac Login"
    268         SSPIAuth On
    269         SSPIAuthoritative On
    270         SSPIDomain MyLocalDomain
    271         SSPIOfferBasic On
    272         SSPIOmitDomain Off
    273         SSPIBasicPreferred On
    274         Require valid-user
    275     </Location>
    276 }}}
    277 
    278 Using the above, usernames in Trac will be of the form `DOMAIN\username`, so
    279 you may have to re-add permissions and such. If you do not want the domain to
    280 be part of the username, set `SSPIOmitDomain On` instead.
    281 
    282 Some common problems with SSPI authentication: [trac:#1055], [trac:#1168] and [trac:#3338].
    283 
    284 See also [trac:TracOnWindows/Advanced].
    285 
    286 === Using Apache authentication with the Account Manager plugin's Login form ===
    287 
    288 To begin with, see the basic instructions for using the Account Manager plugin's [http://trac-hacks.org/wiki/AccountManagerPlugin/Modules#LoginModule Login module] and its [http://trac-hacks.org/wiki/AccountManagerPlugin/AuthStores#HttpAuthStore HttpAuthStore authentication module].
    289 
    290 '''Note:''' If is difficult to get !HttpAuthStore to work with WSGI when using any Account Manager version prior to acct_mgr-0.4. Upgrading is recommended.
    291 
    292 Here is an example (from the !HttpAuthStore link) using acct_mgr-0.4 for hosting a single project:
    293 {{{
    294 [components]
    295 ; be sure to enable the component
    296 acct_mgr.http.HttpAuthStore = enabled
    297 
    298 [account-manager]
    299 ; configure the plugin to use a page that is secured with http authentication
    300 authentication_url = /authFile
    301 password_store = HttpAuthStore
    302 }}}
    303 This will generally be matched with an Apache config like:
    304 {{{
    305 <Location /authFile>
    306    …HTTP authentication configuration…
    307    Require valid-user
    308 </Location>
    309 }}}
    310 Note that '''authFile''' need not exist. See the !HttpAuthStore link above for examples where multiple Trac projects are hosted on a server.
    311 
    312 === Example: Apache/mod_wsgi with Basic Authentication, Trac being at the root of a virtual host
    313 
    314 Per the mod_wsgi documentation linked to above, here is an example Apache configuration that a) serves the Trac instance from a virtualhost subdomain and b) uses Apache basic authentication for Trac authentication.
    315 
    316 
    317 If you want your Trac to be served from e.g. !http://trac.my-proj.my-site.org, then from the folder e.g. `/home/trac-for-my-proj`, if you used the command `trac-admin the-env initenv` to create a folder `the-env`, and you used `trac-admin the-env deploy the-deploy` to create a folder `the-deploy`, then first:
    318 
    319 Create the htpasswd file:
    320 {{{
    321 cd /home/trac-for-my-proj/the-env
    322 htpasswd -c htpasswd firstuser
    323 ### and add more users to it as needed:
    324 htpasswd htpasswd seconduser
    325 }}}
    326 (keep the file above your document root for security reasons)
    327 
    328 Create this file e.g. (ubuntu) `/etc/apache2/sites-enabled/trac.my-proj.my-site.org.conf` with the following contents:
    329 
    330 {{{
    331 <Directory /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi>
    332   WSGIApplicationGroup %{GLOBAL}
    333   Order deny,allow
    334   Allow from all
    335 </Directory>
    336 
    337 <VirtualHost *:80>
    338   ServerName trac.my-proj.my-site.org
    339   DocumentRoot /home/trac-for-my-proj/the-env/htdocs/
    340   WSGIScriptAlias / /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi
    341   <Location '/'>
    342     AuthType Basic
    343     AuthName "Trac"
    344     AuthUserFile /home/trac-for-my-proj/the-env/htpasswd
    345     Require valid-user
    346   </Location>
    347 </VirtualHost>
    348 
    349 }}}
    350 
    351 Note: for subdomains to work you would probably also need to alter `/etc/hosts` and add A-Records to your host's DNS.
    352 
    353 
    354 == Troubleshooting
    355 
    356 === Use a recent version
    357 
    358 Please use either version 1.6, 2.4 or later of `mod_wsgi`. Versions prior to 2.4 in the 2.X branch have problems with some Apache configurations that use WSGI file wrapper extension. This extension is used in Trac to serve up attachments and static media files such as style sheets. If you are affected by this problem attachments will appear to be empty and formatting of HTML pages will appear not to work due to style sheet files not loading properly. Another frequent symptom is that binary attachment downloads are truncated. See mod_wsgi tickets [http://code.google.com/p/modwsgi/issues/detail?id=100 #100] and [http://code.google.com/p/modwsgi/issues/detail?id=132 #132].
     72For troubleshooting tips, see the [TracModPython#Troubleshooting mod_python troubleshooting] section, as most Apache-related issues are quite similar, plus discussion of potential [http://code.google.com/p/modwsgi/wiki/ApplicationIssues application issues] when using mod_wsgi.
    35973
    36074''Note: using mod_wsgi 2.5 and Python 2.6.1 gave an Internal Server Error on my system (Apache 2.2.11 and Trac 0.11.2.1). Upgrading to Python 2.6.2 (as suggested [http://www.mail-archive.com/modwsgi@googlegroups.com/msg01917.html here]) solved this for me[[BR]]-- Graham Shanks''
    36175
    362 === Getting Trac to work nicely with SSPI and 'Require Group' ===
     76== Trac with PostgreSQL ==
     77
     78When using the mod_wsgi adapter with multiple Trac instances and PostgreSQL (or MySQL?) as a database back-end the server can get a lot of open database connections. (and thus PostgreSQL processes)
     79
     80A workable solution is to disabled connection pooling in Trac. This is done by setting poolable = False in trac.db.postgres_backend on the PostgreSQLConnection class.
     81
     82But it's not necessary to edit the source of trac, the following lines in trac.wsgi will also work:
     83
     84{{{
     85import trac.db.postgres_backend
     86trac.db.postgres_backend.PostgreSQLConnection.poolable = False
     87}}}
     88
     89Now Trac drops the connection after serving a page and the connection count on the database will be kept minimal.
     90
     91== Getting Trac to work nicely with SSPI and 'Require Group' ==
    36392If like me you've set Trac up on Apache, Win32 and configured SSPI, but added a 'Require group' option to your apache configuration, then the SSPIOmitDomain option is probably not working.  If its not working your usernames in trac are probably looking like 'DOMAIN\user' rather than 'user'.
    36493
    36594This WSGI script 'fixes' things, hope it helps:
    366 {{{#!python
     95{{{
    36796import os
    36897import trac.web.main
    … …  
    376105    return trac.web.main.dispatch_request(environ, start_response)
    377106}}}
    378 
    379 
    380 === Trac with PostgreSQL ===
    381 
    382 When using the mod_wsgi adapter with multiple Trac instances and PostgreSQL (or MySQL?) as a database back-end, the server ''may'' create a lot of open database connections and thus PostgreSQL processes.
    383 
    384 A somewhat brutal workaround is to disabled connection pooling in Trac. This is done by setting `poolable = False` in `trac.db.postgres_backend` on the `PostgreSQLConnection` class.
    385 
    386 But it's not necessary to edit the source of Trac, the following lines in `trac.wsgi` will also work:
    387 
    388 {{{
    389 import trac.db.postgres_backend
    390 trac.db.postgres_backend.PostgreSQLConnection.poolable = False
    391 }}}
    392 
    393 Now Trac drops the connection after serving a page and the connection count on the database will be kept minimal.
    394 
    395 //This is not a recommended approach though. See also the notes at the bottom of the [http://code.google.com/p/modwsgi/wiki/IntegrationWithTrac mod_wsgi's IntegrationWithTrac] wiki page.//
    396 
    397 === Other resources
    398 
    399 For more troubleshooting tips, see also the [TracModPython#Troubleshooting mod_python troubleshooting] section, as most Apache-related issues are quite similar, plus discussion of potential [http://code.google.com/p/modwsgi/wiki/ApplicationIssues application issues] when using mod_wsgi.
    400 
    401 
    402107----
    403108See also:  TracGuide, TracInstall, [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]