Changes between Version 2 and Version 3 of TracModWSGI


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Timestamp:
Nov 17, 2014, 9:39:05 PM (10 years ago)
Author:
trac
Comment:

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  • TracModWSGI

    v2 v3  
    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].''
    4 
    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.
    6 
    7 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). This file can be created using '''trac-admin <env> deploy <dir>''' command which automatically substitutes required paths.
    8 
    9 {{{
    10 #!python
     3
     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 performance.
     5
     6[[PageOutline(2-3,Overview,inline)]]
     7
     8== The `trac.wsgi` script
     9
     10Trac 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
     13In its simplest form, the script could be:
     14
     15{{{#!python
    1116import os
    1217
    … …  
    2025The `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.
    2126
    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:
    23 
    24 {{{
    25 #!python
     27On Windows:
     28 - If run under the user's session, the Python Egg cache can be found in `%AppData%\Roaming`, for example:
     29{{{#!python
     30os.environ['PYTHON_EGG_CACHE'] = r'C:\Users\Administrator\AppData\Roaming\Python-Eggs'
     31}}}
     32 - If run under a Window service, you should create a directory for Python Egg cache.
     33{{{#!python
     34os.environ['PYTHON_EGG_CACHE'] = r'C:\Trac-Python-Eggs'
     35}}}
     36
     37=== A more elaborate script
     38
     39If 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.
     40
     41To solve this problem, use the following `.wsgi` file instead:
     42{{{#!python
    2643import os
    2744
    … …  
    3451}}}
    3552
    36 For 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`.
    37 
    38 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 on top of the wsgi script:
    39 
    40 {{{
    41 #!python
     53For 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.
     54
     55If 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:
     56
     57{{{#!python
    4258import site
    4359site.addsitedir('/usr/local/trac/lib/python2.4/site-packages')
    4460}}}
    4561
    46 Change it according to the path you installed the trac libs at.
    47 
    48 After you've done preparing your wsgi-script, add the following to your httpd.conf.
     62Change it according to the path you installed the Trac libs at.
     63
     64=== Recommended `trac.wsgi` script
     65
     66A 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).
     67
     68
     69== Mapping requests to the script
     70
     71After you've done preparing your .wsgi script, add the following to your Apache configuration file (`httpd.conf` for example).
    4972
    5073{{{
    … …  
    5881}}}
    5982
    60 Here, 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.
    61 
    62 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):
    63 
    64 {{{
     83Here, the script is in a subdirectory of the Trac environment.
     84
     85If you followed the directions [TracInstall#cgi-bin Generating the Trac cgi-bin directory], your Apache configuration file should look like following:
     86
     87{{{
     88WSGIScriptAlias /trac /usr/share/trac/cgi-bin/trac.wsgi
     89
     90<Directory /usr/share/trac/cgi-bin>
     91    WSGIApplicationGroup %{GLOBAL}
     92    Order deny,allow
     93    Allow from all
     94</Directory>
     95}}}
     96
     97In 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.
     98
     99To 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):
     100
     101{{{#!python
    65102def application(environ, start_response):
    66103        start_response('200 OK',[('Content-type','text/html')])
    … …  
    68105}}}
    69106
    70 See also the mod_wsgi [http://code.google.com/p/modwsgi/wiki/IntegrationWithTrac installation instructions] for Trac.
    71 
    72 For 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.
    73 
    74 ''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''
    75 
    76 == Apache Basic Authentication for Trac thru mod_wsgi ==
    77 
    78 Per the mod_wsgi documentation linked to above, here is an example Apache configuration that a) serves the trac from a virtualhost subdomain and b) uses Apache basic authentication for Trac authentication.
    79 
    80 
    81 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:
    82 
    83 create the htpasswd file:
     107For 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.
     108
     109
     110== Configuring Authentication
     111
     112We describe in the the following sections different methods for setting up authentication.
     113
     114See also [http://httpd.apache.org/docs/2.2/howto/auth.html Authentication, Authorization and Access Control] in the Apache guide.
     115
     116=== Using Basic Authentication ===
     117
     118The simplest way to enable authentication with Apache is to create a password file. Use the `htpasswd` program to create the password file:
     119{{{
     120$ htpasswd -c /somewhere/trac.htpasswd admin
     121New password: <type password>
     122Re-type new password: <type password again>
     123Adding password for user admin
     124}}}
     125
     126After the first user, you dont need the "-c" option anymore:
     127{{{
     128$ htpasswd /somewhere/trac.htpasswd john
     129New password: <type password>
     130Re-type new password: <type password again>
     131Adding password for user john
     132}}}
     133
     134  ''See the man page for `htpasswd` for full documentation.''
     135
     136After you've created the users, you can set their permissions using TracPermissions.
     137
     138Now, you'll need to enable authentication against the password file in the Apache configuration:
     139{{{
     140<Location "/trac/login">
     141  AuthType Basic
     142  AuthName "Trac"
     143  AuthUserFile /somewhere/trac.htpasswd
     144  Require valid-user
     145</Location>
     146}}}
     147
     148If you're hosting multiple projects you can use the same password file for all of them:
     149{{{
     150<LocationMatch "/trac/[^/]+/login">
     151  AuthType Basic
     152  AuthName "Trac"
     153  AuthUserFile /somewhere/trac.htpasswd
     154  Require valid-user
     155</LocationMatch>
     156}}}
     157Note that neither a file nor a directory named 'login' needs to exist.[[BR]]
     158See also the [http://httpd.apache.org/docs/2.2/mod/mod_auth_basic.html mod_auth_basic] documentation.
     159
     160=== Using Digest Authentication ===
     161
     162For better security, it is recommended that you either enable SSL or at least use the “digest” authentication scheme instead of “Basic”.
     163
     164You'll have to create your `.htpasswd` file with the `htdigest` command instead of `htpasswd`, as follows:
     165{{{
     166# htdigest -c /somewhere/trac.htpasswd trac admin
     167}}}
     168
     169The "trac" parameter above is the "realm", and will have to be reused in the Apache configuration in the !AuthName directive:
     170
     171{{{
     172<Location "/trac/login">
     173
     174    AuthType Digest
     175    AuthName "trac"
     176    AuthDigestDomain /trac
     177    AuthUserFile /somewhere/trac.htpasswd
     178    Require valid-user
     179</Location>
     180}}}
     181
     182For multiple environments, you can use the same `LocationMatch` as described with the previous method.
     183
     184'''Note: `Location` cannot be used inside .htaccess files, but must instead live within the main httpd.conf file. If you are on a shared server, you therefore will not be able to provide this level of granularity. '''
     185
     186Don't forget to activate the mod_auth_digest. For example, on a Debian 4.0r1 (etch) system:
     187{{{
     188    LoadModule auth_digest_module /usr/lib/apache2/modules/mod_auth_digest.so
     189}}}
     190
     191
     192See also the [http://httpd.apache.org/docs/2.2/mod/mod_auth_digest.html mod_auth_digest] documentation.
     193
     194=== Using LDAP Authentication
     195
     196Configuration 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)
     197
     1981. You need to load the following modules in Apache httpd.conf
     199{{{
     200LoadModule ldap_module modules/mod_ldap.so
     201LoadModule authnz_ldap_module modules/mod_authnz_ldap.so
     202}}}
     203
     2042. Your httpd.conf also needs to look something like:
     205
     206{{{
     207<Location /trac/>
     208  # (if you're using it, mod_python specific settings go here)
     209  Order deny,allow
     210  Deny from all
     211  Allow from 192.168.11.0/24
     212  AuthType Basic
     213  AuthName "Trac"
     214  AuthBasicProvider "ldap"
     215  AuthLDAPURL "ldap://127.0.0.1/dc=example,dc=co,dc=ke?uid?sub?(objectClass=inetOrgPerson)"
     216  authzldapauthoritative Off
     217  Require valid-user
     218</Location>
     219}}}
     220
     221
     2223. You can use the LDAP interface as a way to authenticate to a Microsoft Active Directory:
     223
     224
     225Use the following as your LDAP URL:
     226{{{
     227    AuthLDAPURL "ldap://directory.example.com:3268/DC=example,DC=com?sAMAccountName?sub?(objectClass=user)"
     228}}}
     229
     230You will also need to provide an account for Apache to use when checking
     231credentials. As this password will be listed in plaintext in the
     232config, you should be sure to use an account specifically for this task:
     233{{{
     234    AuthLDAPBindDN ldap-auth-user@example.com
     235    AuthLDAPBindPassword "password"
     236}}}
     237
     238The whole section looks like:
     239{{{
     240<Location /trac/>
     241  # (if you're using it, mod_python specific settings go here)
     242  Order deny,allow
     243  Deny from all
     244  Allow from 192.168.11.0/24
     245  AuthType Basic
     246  AuthName "Trac"
     247  AuthBasicProvider "ldap"
     248  AuthLDAPURL "ldap://adserver.company.com:3268/DC=company,DC=com?sAMAccountName?sub?(objectClass=user)"
     249  AuthLDAPBindDN       ldap-auth-user@company.com
     250  AuthLDAPBindPassword "the_password"
     251  authzldapauthoritative Off
     252  # require valid-user
     253  require ldap-group CN=Trac Users,CN=Users,DC=company,DC=com
     254</Location>
     255}}}
     256
     257Note 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.
     258
     259Note 2: You can also require the user be a member of a certain LDAP group, instead of
     260just having a valid login:
     261{{{
     262    Require ldap-group CN=Trac Users,CN=Users,DC=example,DC=com
     263}}}
     264
     265See also:
     266  - [http://httpd.apache.org/docs/2.2/mod/mod_authnz_ldap.html mod_authnz_ldap], documentation for mod_authnz_ldap
     267   
     268 - [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.
     269 - [http://trac-hacks.org/wiki/LdapPlugin TracHacks:LdapPlugin] for storing TracPermissions in LDAP.
     270
     271=== Using SSPI Authentication
     272
     273If you are using Apache on Windows, you can use mod_auth_sspi to provide
     274single-sign-on. Download the module from the !SourceForge [http://sourceforge.net/projects/mod-auth-sspi/ mod-auth-sspi project] and then add the
     275following to your !VirtualHost:
     276{{{
     277    <Location /trac/login>
     278        AuthType SSPI
     279        AuthName "Trac Login"
     280        SSPIAuth On
     281        SSPIAuthoritative On
     282        SSPIDomain MyLocalDomain
     283        SSPIOfferBasic On
     284        SSPIOmitDomain Off
     285        SSPIBasicPreferred On
     286        Require valid-user
     287    </Location>
     288}}}
     289
     290Using the above, usernames in Trac will be of the form `DOMAIN\username`, so
     291you may have to re-add permissions and such. If you do not want the domain to
     292be part of the username, set `SSPIOmitDomain On` instead.
     293
     294Some common problems with SSPI authentication: [trac:#1055], [trac:#1168] and [trac:#3338].
     295
     296See also [trac:TracOnWindows/Advanced].
     297
     298=== Using Apache authentication with the Account Manager plugin's Login form ===
     299
     300To 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].
     301
     302'''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.
     303
     304Here is an example (from the !HttpAuthStore link) using acct_mgr-0.4 for hosting a single project:
     305{{{
     306[components]
     307; be sure to enable the component
     308acct_mgr.http.HttpAuthStore = enabled
     309
     310[account-manager]
     311; configure the plugin to use a page that is secured with http authentication
     312authentication_url = /authFile
     313password_store = HttpAuthStore
     314}}}
     315This will generally be matched with an Apache config like:
     316{{{
     317<Location /authFile>
     318   …HTTP authentication configuration…
     319   Require valid-user
     320</Location>
     321}}}
     322Note that '''authFile''' need not exist (unless you are using Account Manager older than 0.4). See the !HttpAuthStore link above for examples where multiple Trac projects are hosted on a server.
     323
     324=== Example: Apache/mod_wsgi with Basic Authentication, Trac being at the root of a virtual host
     325
     326Per 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.
     327
     328
     329If 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:
     330
     331Create the htpasswd file:
    84332{{{
    85333cd /home/trac-for-my-proj/the-env
    … …  
    88336htpasswd htpasswd seconduser
    89337}}}
    90 (for security keep the file above your document root)
    91 
    92 create this file e.g. (ubuntu) {{{/etc/apache2/sites-enabled/trac.my-proj.my-site.org.conf}}} with these contents:
     338(keep the file above your document root for security reasons)
     339
     340Create this file e.g. (ubuntu) `/etc/apache2/sites-enabled/trac.my-proj.my-site.org.conf` with the following contents:
    93341
    94342{{{
    … …  
    113361}}}
    114362
    115 
    116 (for subdomains to work you would probably also need to alter /etc/hosts and add A-Records to your host's DNS.)
    117 
    118 == Trac with PostgreSQL ==
    119 
    120 When 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)
    121 
    122 A 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.
    123 
    124 But it's not necessary to edit the source of trac, the following lines in trac.wsgi will also work:
    125 
    126 {{{
    127 import trac.db.postgres_backend
    128 trac.db.postgres_backend.PostgreSQLConnection.poolable = False
    129 }}}
    130 
    131 Now Trac drops the connection after serving a page and the connection count on the database will be kept minimal.
    132 
    133 == Getting Trac to work nicely with SSPI and 'Require Group' ==
     363Note: for subdomains to work you would probably also need to alter `/etc/hosts` and add A-Records to your host's DNS.
     364
     365
     366== Troubleshooting
     367
     368=== Use a recent version
     369
     370Please 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].
     371
     372''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''
     373
     374If you plan to use `mod_wsgi` in embedded mode on Windows or with the MPM worker on Linux, then you'll even need version 0.3.4 or greater (see [trac:#10675] for details).
     375
     376=== Getting Trac to work nicely with SSPI and 'Require Group' ===
    134377If 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'.
    135378
    136379This WSGI script 'fixes' things, hope it helps:
    137 {{{
     380{{{#!python
    138381import os
    139382import trac.web.main
    … …  
    147390    return trac.web.main.dispatch_request(environ, start_response)
    148391}}}
     392
     393
     394=== Trac with PostgreSQL ===
     395
     396When 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.
     397
     398A 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.
     399
     400But it's not necessary to edit the source of Trac, the following lines in `trac.wsgi` will also work:
     401
     402{{{#!python
     403import trac.db.postgres_backend
     404trac.db.postgres_backend.PostgreSQLConnection.poolable = False
     405}}}
     406
     407or
     408
     409{{{#!python
     410import trac.db.mysql_backend
     411trac.db.mysql_backend.MySQLConnection.poolable = False
     412}}}
     413
     414Now Trac drops the connection after serving a page and the connection count on the database will be kept minimal.
     415
     416//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.//
     417
     418=== Other resources
     419
     420For 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. The wsgi page also has a [http://code.google.com/p/modwsgi/wiki/IntegrationWithTrac Integration With Trac] document.
     421
     422
    149423----
    150424See also:  TracGuide, TracInstall, [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]