Changes between Initial Version and Version 1 of TracModWSGI


Ignore:
Timestamp:
06/11/16 19:55:22 (4 years ago)
Author:
trac
Comment:

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  • TracModWSGI

    v1 v1  
     1= Trac and mod_wsgi
     2
     3[https://github.com/GrahamDumpleton/mod_wsgi 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.
     4
     5[[PageOutline(2-3,Overview,inline)]]
     6
     7== The `trac.wsgi` script
     8
     9Trac can be run on top of mod_wsgi with the help of an application script, which is just a Python file saved with a `.wsgi` extension.
     10
     11A 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. The script should be sufficient for most installations and users not wanting more information can proceed to [#Mappingrequeststothescript configuring Apache].
     12
     13If you are using Trac with multiple projects, you can specify their common parent directory using the `TRAC_ENV_PARENT_DIR` in trac.wsgi:
     14{{{#!python
     15def application(environ, start_request):
     16    # Add this to config when you have multiple projects                                             
     17    environ.setdefault('trac.env_parent_dir', '/usr/share/trac/projects') 
     18    ..
     19}}}
     20
     21=== A very basic script
     22In its simplest form, the script could be:
     23
     24{{{#!python
     25import os
     26
     27os.environ['TRAC_ENV'] = '/usr/local/trac/mysite'
     28os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
     29
     30import trac.web.main
     31application = trac.web.main.dispatch_request
     32}}}
     33
     34The `TRAC_ENV` variable should naturally be the directory for your Trac environment, and the `PYTHON_EGG_CACHE` should be a directory where Python can temporarily extract Python eggs. If you have several Trac environments in a directory, you can also use `TRAC_ENV_PARENT_DIR` instead of `TRAC_ENV`.
     35
     36On Windows:
     37 - If run under the user's session, the Python Egg cache can be found in `%AppData%\Roaming`, for example:
     38{{{#!python
     39os.environ['PYTHON_EGG_CACHE'] = r'C:\Users\Administrator\AppData\Roaming\Python-Eggs'
     40}}}
     41 - If run under a Window service, you should create a directory for Python Egg cache:
     42{{{#!python
     43os.environ['PYTHON_EGG_CACHE'] = r'C:\Trac-Python-Eggs'
     44}}}
     45
     46=== A more elaborate script
     47
     48If you are 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.
     49
     50To solve this problem, use the following `.wsgi` file instead:
     51{{{#!python
     52import os
     53
     54os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
     55
     56import trac.web.main
     57def application(environ, start_response):
     58  environ['trac.env_path'] = '/usr/local/trac/mysite'
     59  return trac.web.main.dispatch_request(environ, start_response)
     60}}}
     61
     62For 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.
     63
     64If you have installed Trac and Python 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:
     65
     66{{{#!python
     67import site
     68site.addsitedir('/usr/local/trac/lib/python2.4/site-packages')
     69}}}
     70
     71Change it according to the path you installed the Trac libs at.
     72
     73== Mapping requests to the script
     74
     75After preparing your .wsgi script, add the following to your Apache configuration file, typically `httpd.conf`:
     76
     77{{{#!apache
     78WSGIScriptAlias /trac /usr/local/trac/mysite/apache/mysite.wsgi
     79
     80<Directory /usr/local/trac/mysite/apache>
     81    WSGIApplicationGroup %{GLOBAL}
     82    # For Apache 2.2
     83    <IfModule !mod_authz_core.c>
     84        Order deny,allow
     85        Allow from all
     86    </IfModule>
     87    # For Apache 2.4
     88    <IfModule mod_authz_core.c>
     89        Require all granted
     90    </IfModule>
     91</Directory>
     92}}}
     93
     94Here, the script is in a subdirectory of the Trac environment.
     95
     96If you followed the directions [TracInstall#cgi-bin Generating the Trac cgi-bin directory], your Apache configuration file should look like following:
     97
     98{{{#!apache
     99WSGIScriptAlias /trac /usr/share/trac/cgi-bin/trac.wsgi
     100
     101<Directory /usr/share/trac/cgi-bin>
     102    WSGIApplicationGroup %{GLOBAL}
     103    # For Apache 2.2
     104    <IfModule !mod_authz_core.c>
     105        Order deny,allow
     106        Allow from all
     107    </IfModule>
     108    # For Apache 2.4
     109    <IfModule mod_authz_core.c>
     110        Require all granted
     111    </IfModule>
     112</Directory>
     113}}}
     114
     115In 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. After adding this configuration, restart Apache, and then it should work.
     116
     117To 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):
     118
     119{{{#!python
     120def application(environ, start_response):
     121        start_response('200 OK',[('Content-type','text/html')])
     122        return ['<html><body>Hello World!</body></html>']
     123}}}
     124
     125For 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.
     126
     127== Configuring Authentication
     128
     129The following sections describe different methods for setting up authentication. See also [http://httpd.apache.org/docs/2.2/howto/auth.html Authentication, Authorization and Access Control] in the Apache guide.
     130
     131=== Using Basic Authentication
     132
     133The simplest way to enable authentication with Apache is to create a password file. Use the `htpasswd` program as follows:
     134{{{#!sh
     135$ htpasswd -c /somewhere/trac.htpasswd admin
     136New password: <type password>
     137Re-type new password: <type password again>
     138Adding password for user admin
     139}}}
     140
     141After the first user, you don't need the "-c" option anymore:
     142{{{#!sh
     143$ htpasswd /somewhere/trac.htpasswd john
     144New password: <type password>
     145Re-type new password: <type password again>
     146Adding password for user john
     147}}}
     148
     149  ''See the man page for `htpasswd` for full documentation.''
     150
     151After you've created the users, you can set their permissions using TracPermissions.
     152
     153Now, you need to enable authentication against the password file in the Apache configuration:
     154{{{#!apache
     155<Location "/trac/login">
     156  AuthType Basic
     157  AuthName "Trac"
     158  AuthUserFile /somewhere/trac.htpasswd
     159  Require valid-user
     160</Location>
     161}}}
     162
     163If you are hosting multiple projects, you can use the same password file for all of them:
     164{{{#!apache
     165<LocationMatch "/trac/[^/]+/login">
     166  AuthType Basic
     167  AuthName "Trac"
     168  AuthUserFile /somewhere/trac.htpasswd
     169  Require valid-user
     170</LocationMatch>
     171}}}
     172Note that neither a file nor a directory named 'login' needs to exist.[[BR]]
     173See also the [http://httpd.apache.org/docs/2.2/mod/mod_auth_basic.html mod_auth_basic] documentation.
     174
     175=== Using Digest Authentication
     176
     177For better security, it is recommended that you either enable SSL or at least use the “digest” authentication scheme instead of “Basic”.
     178
     179You have to create your `.htpasswd` file with the `htdigest` command instead of `htpasswd`, as follows:
     180{{{#!sh
     181$ htdigest -c /somewhere/trac.htpasswd trac admin
     182}}}
     183
     184The "trac" parameter above is the "realm", and will have to be reused in the Apache configuration in the !AuthName directive:
     185
     186{{{#!apache
     187<Location "/trac/login">
     188  AuthType Digest
     189  AuthName "trac"
     190  AuthDigestDomain /trac
     191  AuthUserFile /somewhere/trac.htpasswd
     192  Require valid-user
     193</Location>
     194}}}
     195
     196For multiple environments, you can use the same `LocationMatch` as described with the previous method.
     197
     198'''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. '''
     199
     200Don't forget to activate the mod_auth_digest. For example, on a Debian 4.0r1 (etch) system:
     201{{{#!apache
     202  LoadModule auth_digest_module /usr/lib/apache2/modules/mod_auth_digest.so
     203}}}
     204
     205See also the [http://httpd.apache.org/docs/2.2/mod/mod_auth_digest.html mod_auth_digest] documentation.
     206
     207=== Using LDAP Authentication
     208
     209Configuration for [http://httpd.apache.org/docs/2.2/mod/mod_ldap.html mod_ldap] authentication in Apache is more involved (httpd 2.2.x and OpenLDAP: slapd 2.3.19).
     210
     2111. You need to load the following modules in Apache httpd.conf:
     212{{{#!apache
     213  LoadModule ldap_module modules/mod_ldap.so
     214  LoadModule authnz_ldap_module modules/mod_authnz_ldap.so
     215}}}
     2161. Your httpd.conf also needs to look something like:
     217{{{#!apache
     218<Location /trac/>
     219  # (if you're using it, mod_python specific settings go here)
     220  Order deny,allow
     221  Deny from all
     222  Allow from 192.168.11.0/24
     223  AuthType Basic
     224  AuthName "Trac"
     225  AuthBasicProvider "ldap"
     226  AuthLDAPURL "ldap://127.0.0.1/dc=example,dc=co,dc=ke?uid?sub?(objectClass=inetOrgPerson)"
     227  authzldapauthoritative Off
     228  Require valid-user
     229</Location>
     230}}}
     2311. You can use the LDAP interface as a way to authenticate to a Microsoft Active Directory. Use the following as your LDAP URL:
     232{{{#!apache
     233  AuthLDAPURL "ldap://directory.example.com:3268/DC=example,DC=com?sAMAccountName?sub?(objectClass=user)"
     234}}}
     235 You will also need to provide an account for Apache to use when checking credentials. As this password will be listed in plaintext in the config, you need to use an account specifically for this task:
     236{{{#!apache
     237  AuthLDAPBindDN ldap-auth-user@example.com
     238  AuthLDAPBindPassword "password"
     239}}}
     240 The whole section looks like:
     241{{{#!apache
     242<Location /trac/>
     243  # (if you're using it, mod_python specific settings go here)
     244  Order deny,allow
     245  Deny from all
     246  Allow from 192.168.11.0/24
     247  AuthType Basic
     248  AuthName "Trac"
     249  AuthBasicProvider "ldap"
     250  AuthLDAPURL "ldap://adserver.company.com:3268/DC=company,DC=com?sAMAccountName?sub?(objectClass=user)"
     251  AuthLDAPBindDN       ldap-auth-user@company.com
     252  AuthLDAPBindPassword "the_password"
     253  authzldapauthoritative Off
     254  # require valid-user
     255  Require ldap-group CN=Trac Users,CN=Users,DC=company,DC=com
     256</Location>
     257}}}
     258
     259Note 1: This is the case where the LDAP search will get around the multiple OUs, conecting to the Global Catalog Server portion of AD. Note 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.
     260
     261Note 2: You can also require the user be a member of a certain LDAP group, instead of just having a valid login:
     262{{{#!apache
     263  Require ldap-group CN=Trac Users,CN=Users,DC=example,DC=com
     264}}}
     265
     266See also:
     267 - [http://httpd.apache.org/docs/2.2/mod/mod_authnz_ldap.html mod_authnz_ldap], documentation for mod_authnz_ldap.   
     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 single-sign-on. Download the module from the !SourceForge [http://sourceforge.net/projects/mod-auth-sspi/ mod-auth-sspi project] and then add the following to your !VirtualHost:
     274{{{#!apache
     275<Location /trac/login>
     276  AuthType SSPI
     277  AuthName "Trac Login"
     278  SSPIAuth On
     279  SSPIAuthoritative On
     280  SSPIDomain MyLocalDomain
     281  SSPIOfferBasic On
     282  SSPIOmitDomain Off
     283  SSPIBasicPreferred On
     284  Require valid-user
     285</Location>
     286}}}
     287
     288Using the above, usernames in Trac will be of the form `DOMAIN\username`, so you may have to re-add permissions and such. If you do not want the domain to be part of the username, set `SSPIOmitDomain On` instead.
     289
     290Some common problems with SSPI authentication: [trac:#1055], [trac:#1168] and [trac:#3338].
     291
     292See also [trac:TracOnWindows/Advanced].
     293
     294=== Using CA !SiteMinder Authentication
     295Setup CA !SiteMinder to protect your Trac login URL (e.g. `/trac/login`).  Also, make sure the policy is set to include the HTTP_REMOTE_USER variable.  If your site allows it, you can set this in LocalConfig.conf:
     296{{{#!apache
     297RemoteUserVar="WHATEVER_IT_SHOULD_BE"
     298SetRemoteUser="YES"
     299}}}
     300The specific variable is site-dependent.  Ask your site administrator.  If your site does not allow the use of LocalConfig.conf for security reasons, have your site administrator set the policy on the server to set REMOTE_USER.
     301
     302Also add a !LogOffUri parameter to the agent configuration (e.g. `/trac/logout`).
     303
     304Then modify the trac.wsgi script generated using `trac-admin <env> deploy <dir>` to add the following lines, which extract the `HTTP_REMOTE_USER` variable and set it to `REMOTE_USER`:
     305
     306{{{#!python
     307def application(environ, start_request):
     308    # Set authenticated username on CA SiteMinder to REMOTE_USER variable
     309    # strip() is used to remove any spaces on the end of the string
     310    if 'HTTP_SM_USER' in environ:
     311        environ['REMOTE_USER'] = environ['HTTP_REMOTE_USER'].strip()
     312    ...
     313}}}
     314
     315Note:  you do not need any Apache "Location" directives.
     316
     317=== Using Apache authentication with the Account Manager plugin's Login form ===
     318
     319To 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].
     320
     321'''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.
     322
     323Here is an example (from the !HttpAuthStore link) using acct_mgr-0.4 for hosting a single project:
     324{{{#!ini
     325[components]
     326; be sure to enable the component
     327acct_mgr.http.HttpAuthStore = enabled
     328
     329[account-manager]
     330; configure the plugin to use a page that is secured with http authentication
     331authentication_url = /authFile
     332password_store = HttpAuthStore
     333}}}
     334This will generally be matched with an Apache config like:
     335{{{#!apache
     336<Location /authFile>
     337   # HTTP authentication configuration
     338   Require valid-user
     339</Location>
     340}}}
     341Note 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.
     342
     343=== Example: Apache/mod_wsgi with Basic Authentication, Trac being at the root of a virtual host
     344
     345Per the mod_wsgi documentation linked to above, here is an example Apache configuration that:
     346 - serves the Trac instance from a virtualhost subdomain
     347 - uses Apache basic authentication for Trac authentication.
     348
     349If 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:
     350
     351Create the htpasswd file:
     352{{{#!sh
     353cd /home/trac-for-my-proj/the-env
     354htpasswd -c htpasswd firstuser
     355### and add more users to it as needed:
     356htpasswd htpasswd seconduser
     357}}}
     358Keep the file above your document root for security reasons.
     359
     360Create this file e.g. (ubuntu) `/etc/apache2/sites-enabled/trac.my-proj.my-site.org.conf` with the following content:
     361
     362{{{#!apache
     363<Directory /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi>
     364  WSGIApplicationGroup %{GLOBAL}
     365  Order deny,allow
     366  Allow from all
     367</Directory>
     368
     369<VirtualHost *:80>
     370  ServerName trac.my-proj.my-site.org
     371  DocumentRoot /home/trac-for-my-proj/the-env/htdocs/
     372  WSGIScriptAlias / /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi
     373  <Location '/'>
     374    AuthType Basic
     375    AuthName "Trac"
     376    AuthUserFile /home/trac-for-my-proj/the-env/htpasswd
     377    Require valid-user
     378  </Location>
     379</VirtualHost>
     380
     381}}}
     382
     383Note: for subdomains to work you would probably also need to alter `/etc/hosts` and add A-Records to your host's DNS.
     384
     385== Troubleshooting
     386
     387=== Use a recent version
     388
     389Please 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].
     390
     391''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''
     392
     393If you plan to use `mod_wsgi` in embedded mode on Windows or with the MPM worker on Linux, then you will need version 3.4 or greater. See [trac:#10675] for details.
     394
     395=== Getting Trac to work nicely with SSPI and 'Require Group'
     396
     397If you have 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 it is not working, your usernames in Trac probably look like 'DOMAIN\user' rather than 'user'.
     398
     399This WSGI script 'fixes' that:
     400{{{#!python
     401import os
     402import trac.web.main
     403
     404os.environ['TRAC_ENV'] = '/usr/local/trac/mysite'
     405os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
     406
     407def application(environ, start_response):
     408    if "\\" in environ['REMOTE_USER']:
     409        environ['REMOTE_USER'] = environ['REMOTE_USER'].split("\\", 1)[1]
     410    return trac.web.main.dispatch_request(environ, start_response)
     411}}}
     412
     413=== Trac with PostgreSQL
     414
     415When using the mod_wsgi adapter with multiple Trac instances and PostgreSQL (or MySQL?) as the database, the server ''may'' create a lot of open database connections and thus PostgreSQL processes.
     416
     417A somewhat brutal workaround is to disable connection pooling in Trac. This is done by setting `poolable = False` in `trac.db.postgres_backend` on the `PostgreSQLConnection` class.
     418
     419But it is not necessary to edit the source of Trac. The following lines in `trac.wsgi` will also work:
     420
     421{{{#!python
     422import trac.db.postgres_backend
     423trac.db.postgres_backend.PostgreSQLConnection.poolable = False
     424}}}
     425
     426or
     427
     428{{{#!python
     429import trac.db.mysql_backend
     430trac.db.mysql_backend.MySQLConnection.poolable = False
     431}}}
     432
     433Now Trac drops the connection after serving a page and the connection count on the database will be kept low.
     434
     435//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.//
     436
     437=== Missing Headers and Footers
     438
     439If python optimizations are enabled, then headers and footers will not be rendered.
     440
     441In your WSGI configuration file, the `WSGIPythonOptimize` setting must be set to `0` as follows (`1` or `2` will not work):
     442
     443{{{#!apache
     444    WSGIPythonOptimize 0
     445}}}
     446
     447On Ubuntu, the WSGI mod configuration is at `/etc/apache2/mods-enabled/wsgi.conf`.
     448
     449NOTE: This is the WSGI equivalent of the same issue that happens with `PythonOptimize On` in [TracModPython#Pagelayoutissues ModPython] (see [trac:#8956]).
     450
     451=== Other resources
     452
     453For 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.
     454
     455----
     456See also: TracGuide, TracInstall, [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]