Changes between Initial Version and Version 1 of TracModWSGI

07/10/20 13:09:46 (2 years ago)



  • TracModWSGI

    v1 v1  
     1= Trac and mod_wsgi
     3[ 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.
     7== The `trac.wsgi` script
     9Trac can be run on top of mod_wsgi with the help of an application script, which is a Python file saved with a `.wsgi` extension.
     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].
     13If you are using Trac with multiple projects, you can specify their common parent directory in `trac.wsgi`:
     15def application(environ, start_request):
     16    # Add this when you have multiple projects
     17    environ.setdefault('trac.env_parent_dir', '/usr/share/trac/projects')
     18    ..
     21Directories residing in `trac.env_parent_dir` that are not environment directories will display an error message on the [TracInterfaceCustomization#ProjectList project index page]. The directories can be excluded by listing them in a `.tracignore` file residing in `trac.env_parent_dir`. Unix [ shell-style wildcard patterns] can be used in the newline separated list of directories.
     23=== A very basic script
     25In its simplest form, the script could be:
     28import os
     30os.environ['TRAC_ENV'] = '/usr/local/trac/mysite'
     31os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
     33import trac.web.main
     34application = trac.web.main.dispatch_request
     37The `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`.
     39On Windows:
     40 - If run under the user's session, the Python Egg cache can be found in `%AppData%\Roaming`, for example:
     42os.environ['PYTHON_EGG_CACHE'] = r'C:\Users\Administrator\AppData\Roaming\Python-Eggs'
     44 - If run under a Window service, you should create a directory for Python Egg cache:
     46os.environ['PYTHON_EGG_CACHE'] = r'C:\Trac-Python-Eggs'
     49=== A more elaborate script
     51If 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.
     53To solve this problem, use the following `.wsgi` file instead:
     55import os
     57os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
     59import trac.web.main
     60def application(environ, start_response):
     61  environ['trac.env_path'] = '/usr/local/trac/mysite'
     62  return trac.web.main.dispatch_request(environ, start_response)
     65For 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.
     67If 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:
     70import site
     74Change it according to the path you installed the Trac libs at.
     76== Mapping requests to the script
     78After preparing your .wsgi script, add the following to your Apache configuration file, typically `httpd.conf`:
     81WSGIScriptAlias /trac /usr/local/trac/mysite/apache/mysite.wsgi
     83<Directory /usr/local/trac/mysite/apache>
     84    WSGIApplicationGroup %{GLOBAL}
     85    # For Apache 2.2
     86    <IfModule !mod_authz_core.c>
     87        Order deny,allow
     88        Allow from all
     89    </IfModule>
     90    # For Apache 2.4
     91    <IfModule mod_authz_core.c>
     92        Require all granted
     93    </IfModule>
     97Here, the script is in a subdirectory of the Trac environment.
     99If you followed the directions [TracInstall#cgi-bin Generating the Trac cgi-bin directory], your Apache configuration file should look like following:
     102WSGIScriptAlias /trac /usr/share/trac/cgi-bin/trac.wsgi
     104<Directory /usr/share/trac/cgi-bin>
     105    WSGIApplicationGroup %{GLOBAL}
     106    # For Apache 2.2
     107    <IfModule !mod_authz_core.c>
     108        Order deny,allow
     109        Allow from all
     110    </IfModule>
     111    # For Apache 2.4
     112    <IfModule mod_authz_core.c>
     113        Require all granted
     114    </IfModule>
     118In 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.
     120To 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):
     123def application(environ, start_response):
     124        start_response('200 OK',[('Content-type','text/html')])
     125        return ['<html><body>Hello World!</body></html>']
     128For more information about using the mod_wsgi specific directives, see the [ mod_wsgi's wiki] and more specifically the [ IntegrationWithTrac] page.
     130== Configuring Authentication
     132The following sections describe different methods for setting up authentication. See also [ Authentication, Authorization and Access Control] in the Apache guide.
     134=== Using Basic Authentication
     136The simplest way to enable authentication with Apache is to create a password file. Use the `htpasswd` program as follows:
     138$ htpasswd -c /somewhere/trac.htpasswd admin
     139New password: <type password>
     140Re-type new password: <type password again>
     141Adding password for user admin
     144After the first user, you don't need the "-c" option anymore:
     146$ htpasswd /somewhere/trac.htpasswd john
     147New password: <type password>
     148Re-type new password: <type password again>
     149Adding password for user john
     152See the man page for `htpasswd` for full documentation.
     154After you've created the users, you can set their permissions using TracPermissions.
     156Now, you need to enable authentication against the password file in the Apache configuration:
     158<Location "/trac/login">
     159  AuthType Basic
     160  AuthName "Trac"
     161  AuthUserFile /somewhere/trac.htpasswd
     162  Require valid-user
     166If you are hosting multiple projects, you can use the same password file for all of them:
     168<LocationMatch "/trac/[^/]+/login">
     169  AuthType Basic
     170  AuthName "Trac"
     171  AuthUserFile /somewhere/trac.htpasswd
     172  Require valid-user
     176Note that neither a file nor a directory named 'login' needs to exist. See also the [ mod_auth_basic] documentation.
     178=== Using Digest Authentication
     180For better security, it is recommended that you either enable SSL or at least use the "digest" authentication scheme instead of "Basic".
     182You have to create your `.htpasswd` file with the `htdigest` command instead of `htpasswd`, as follows:
     184$ htdigest -c /somewhere/trac.htpasswd trac admin
     187The "trac" parameter above is the "realm", and will have to be reused in the Apache configuration in the !AuthName directive:
     190<Location "/trac/login">
     191  AuthType Digest
     192  AuthName "trac"
     193  AuthDigestDomain /trac
     194  AuthUserFile /somewhere/trac.htpasswd
     195  Require valid-user
     199For multiple environments, you can use the same `LocationMatch` as described with the previous method.
     201'''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.
     203Don't forget to activate the mod_auth_digest. For example, on a Debian 4.0r1 (etch) system:
     205  LoadModule auth_digest_module /usr/lib/apache2/modules/
     208See also the [ mod_auth_digest] documentation.
     210=== Using LDAP Authentication
     212Configuration for [ mod_ldap] authentication in Apache is more involved (httpd 2.2+ and OpenLDAP: slapd 2.3.19).
     2141. You need to load the following modules in Apache httpd.conf:
     216  LoadModule ldap_module modules/
     217  LoadModule authnz_ldap_module modules/
     2191. Your httpd.conf also needs to look something like:
     221<Location /trac/>
     222  # (if you're using it, mod_python specific settings go here)
     223  Order deny,allow
     224  Deny from all
     225  Allow from
     226  AuthType Basic
     227  AuthName "Trac"
     228  AuthBasicProvider "ldap"
     229  AuthLDAPURL "ldap://,dc=co,dc=ke?uid?sub?(objectClass=inetOrgPerson)"
     230  authzldapauthoritative Off
     231  Require valid-user
     2341. You can use the LDAP interface as a way to authenticate to a Microsoft Active Directory. Use the following as your LDAP URL:
     236  AuthLDAPURL "ldap://,DC=com?sAMAccountName?sub?(objectClass=user)"
     238 You will also need to provide an account for Apache to use when checking credentials. As this password will be listed in plain text in the configuration, you need to use an account specifically for this task:
     240  AuthLDAPBindDN
     241  AuthLDAPBindPassword "password"
     243 The whole section looks like:
     245<Location /trac/>
     246  # (if you're using it, mod_python specific settings go here)
     247  Order deny,allow
     248  Deny from all
     249  Allow from
     250  AuthType Basic
     251  AuthName "Trac"
     252  AuthBasicProvider "ldap"
     253  AuthLDAPURL "ldap://,DC=com?sAMAccountName?sub?(objectClass=user)"
     254  AuthLDAPBindDN
     255  AuthLDAPBindPassword "the_password"
     256  authzldapauthoritative Off
     257  # require valid-user
     258  Require ldap-group CN=Trac Users,CN=Users,DC=company,DC=com
     262Note 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.
     264Note 2: You can also require the user be a member of a certain LDAP group, instead of just having a valid login:
     266  Require ldap-group CN=Trac Users,CN=Users,DC=example,DC=com
     269See also:
     270 - [ mod_authnz_ldap], documentation for mod_authnz_ldap.
     271 - [ mod_ldap], documentation for mod_ldap, which provides connection pooling and a shared cache.
     272 - [ TracHacks:LdapPlugin] for storing TracPermissions in LDAP.
     274=== Using SSPI Authentication
     276If you are using Apache on Windows, you can use mod_auth_sspi to provide single-sign-on. Download the module from the !SourceForge [ mod-auth-sspi project] and then add the following to your !VirtualHost:
     278<Location /trac/login>
     279  AuthType SSPI
     280  AuthName "Trac Login"
     281  SSPIAuth On
     282  SSPIAuthoritative On
     283  SSPIDomain MyLocalDomain
     284  SSPIOfferBasic On
     285  SSPIOmitDomain Off
     286  SSPIBasicPreferred On
     287  Require valid-user
     291Using 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.
     293Some common problems with SSPI authentication: [trac:#1055], [trac:#1168] and [trac:#3338].
     295See also [trac:TracOnWindows/Advanced].
     297=== Using CA !SiteMinder Authentication
     299Setup CA !SiteMinder to protect your Trac login URL, for example `/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`:
     305The 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.
     307Also add a !LogOffUri parameter to the agent configuration, for example `/trac/logout`.
     309Then 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`:
     312def application(environ, start_request):
     313    # Set authenticated username on CA SiteMinder to REMOTE_USER variable
     314    # strip() is used to remove any spaces on the end of the string
     315    if 'HTTP_SM_USER' in environ:
     316        environ['REMOTE_USER'] = environ['HTTP_REMOTE_USER'].strip()
     317    ...
     320You do not need any Apache "Location" directives.
     322=== Example: Apache/mod_wsgi with Basic Authentication, Trac being at the root of a virtual host
     324Per the mod_wsgi documentation linked to above, here is an example Apache configuration that:
     325 - serves the Trac instance from a virtualhost subdomain
     326 - uses Apache basic authentication for Trac authentication.
     328If you want your Trac to be served from eg !, then from the folder eg `/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:
     330Create the htpasswd file:
     332cd /home/trac-for-my-proj/the-env
     333htpasswd -c htpasswd firstuser
     334### and add more users to it as needed:
     335htpasswd htpasswd seconduser
     338Keep the file above your document root for security reasons.
     340Create this file for example `/etc/apache2/sites-enabled/` on Ubuntu with the following content:
     343<Directory /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi>
     344  WSGIApplicationGroup %{GLOBAL}
     345  Order deny,allow
     346  Allow from all
     349<VirtualHost *:80>
     350  ServerName
     351  DocumentRoot /home/trac-for-my-proj/the-env/htdocs/
     352  WSGIScriptAlias / /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi
     353  <Location '/'>
     354    AuthType Basic
     355    AuthName "Trac"
     356    AuthUserFile /home/trac-for-my-proj/the-env/htpasswd
     357    Require valid-user
     358  </Location>
     363For subdomains to work you would probably also need to alter `/etc/hosts` and add A-Records to your host's DNS.
     365== Troubleshooting
     367=== Use a recent version
     369Please 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 [ #100] and [ #132].
     371'''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 Upgrading to Python 2.6.2 (as suggested [ here]) solved this for me[[BR]]-- Graham Shanks
     373If 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.
     375=== Getting Trac to work nicely with SSPI and 'Require Group'
     377If 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'.
     379This WSGI script fixes that:
     381import os
     382import trac.web.main
     384os.environ['TRAC_ENV'] = '/usr/local/trac/mysite'
     385os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
     387def application(environ, start_response):
     388    if "\\" in environ['REMOTE_USER']:
     389        environ['REMOTE_USER'] = environ['REMOTE_USER'].split("\\", 1)[1]
     390    return trac.web.main.dispatch_request(environ, start_response)
     393=== Trac with PostgreSQL
     395When 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.
     397A 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.
     399But it is not necessary to edit the source of Trac. The following lines in `trac.wsgi` will also work:
     402import trac.db.postgres_backend
     403trac.db.postgres_backend.PostgreSQLConnection.poolable = False
     409import trac.db.mysql_backend
     410trac.db.mysql_backend.MySQLConnection.poolable = False
     413Now Trac drops the connection after serving a page and the connection count on the database will be kept low.
     415//This is not a recommended approach though. See also the notes at the bottom of the [ mod_wsgi's IntegrationWithTrac] wiki page.//
     417=== Other resources
     419For more troubleshooting tips, see also the [TracModPython#Troubleshooting mod_python troubleshooting] section, as most Apache-related issues are quite similar, plus discussion of potential [ application issues] when using mod_wsgi. The wsgi page also has a [ Integration With Trac] document.
     422See also: TracGuide, TracInstall, [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]