Changes between Initial Version and Version 1 of TracModWSGI

11/05/16 17:06:47 (7 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 using the `TRAC_ENV_PARENT_DIR` in trac.wsgi:
     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    ..
     21=== A very basic script
     23In its simplest form, the script could be:
     26import os
     28os.environ['TRAC_ENV'] = '/usr/local/trac/mysite'
     29os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
     31import trac.web.main
     32application = trac.web.main.dispatch_request
     35The `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`.
     37On Windows:
     38 - If run under the user's session, the Python Egg cache can be found in `%AppData%\Roaming`, for example:
     40os.environ['PYTHON_EGG_CACHE'] = r'C:\Users\Administrator\AppData\Roaming\Python-Eggs'
     42 - If run under a Window service, you should create a directory for Python Egg cache:
     44os.environ['PYTHON_EGG_CACHE'] = r'C:\Trac-Python-Eggs'
     47=== A more elaborate script
     49If 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.
     51To solve this problem, use the following `.wsgi` file instead:
     53import os
     55os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
     57import trac.web.main
     58def application(environ, start_response):
     59  environ['trac.env_path'] = '/usr/local/trac/mysite'
     60  return trac.web.main.dispatch_request(environ, start_response)
     63For 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.
     65If 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:
     68import site
     72Change it according to the path you installed the Trac libs at.
     74== Mapping requests to the script
     76After preparing your .wsgi script, add the following to your Apache configuration file, typically `httpd.conf`:
     79WSGIScriptAlias /trac /usr/local/trac/mysite/apache/mysite.wsgi
     81<Directory /usr/local/trac/mysite/apache>
     82    WSGIApplicationGroup %{GLOBAL}
     83    # For Apache 2.2
     84    <IfModule !mod_authz_core.c>
     85        Order deny,allow
     86        Allow from all
     87    </IfModule>
     88    # For Apache 2.4
     89    <IfModule mod_authz_core.c>
     90        Require all granted
     91    </IfModule>
     95Here, the script is in a subdirectory of the Trac environment.
     97If you followed the directions [TracInstall#cgi-bin Generating the Trac cgi-bin directory], your Apache configuration file should look like following:
     100WSGIScriptAlias /trac /usr/share/trac/cgi-bin/trac.wsgi
     102<Directory /usr/share/trac/cgi-bin>
     103    WSGIApplicationGroup %{GLOBAL}
     104    # For Apache 2.2
     105    <IfModule !mod_authz_core.c>
     106        Order deny,allow
     107        Allow from all
     108    </IfModule>
     109    # For Apache 2.4
     110    <IfModule mod_authz_core.c>
     111        Require all granted
     112    </IfModule>
     116In 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.
     118To 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):
     121def application(environ, start_response):
     122        start_response('200 OK',[('Content-type','text/html')])
     123        return ['<html><body>Hello World!</body></html>']
     126For more information about using the mod_wsgi specific directives, see the [ mod_wsgi's wiki] and more specifically the [ IntegrationWithTrac] page.
     128== Configuring Authentication
     130The following sections describe different methods for setting up authentication. See also [ Authentication, Authorization and Access Control] in the Apache guide.
     132=== Using Basic Authentication
     134The simplest way to enable authentication with Apache is to create a password file. Use the `htpasswd` program as follows:
     136$ htpasswd -c /somewhere/trac.htpasswd admin
     137New password: <type password>
     138Re-type new password: <type password again>
     139Adding password for user admin
     142After the first user, you don't need the "-c" option anymore:
     144$ htpasswd /somewhere/trac.htpasswd john
     145New password: <type password>
     146Re-type new password: <type password again>
     147Adding password for user john
     150See the man page for `htpasswd` for full documentation.
     152After you've created the users, you can set their permissions using TracPermissions.
     154Now, you need to enable authentication against the password file in the Apache configuration:
     156<Location "/trac/login">
     157  AuthType Basic
     158  AuthName "Trac"
     159  AuthUserFile /somewhere/trac.htpasswd
     160  Require valid-user
     164If you are hosting multiple projects, you can use the same password file for all of them:
     166<LocationMatch "/trac/[^/]+/login">
     167  AuthType Basic
     168  AuthName "Trac"
     169  AuthUserFile /somewhere/trac.htpasswd
     170  Require valid-user
     174Note that neither a file nor a directory named 'login' needs to exist. See also the [ mod_auth_basic] documentation.
     176=== Using Digest Authentication
     178For better security, it is recommended that you either enable SSL or at least use the "digest" authentication scheme instead of "Basic".
     180You have to create your `.htpasswd` file with the `htdigest` command instead of `htpasswd`, as follows:
     182$ htdigest -c /somewhere/trac.htpasswd trac admin
     185The "trac" parameter above is the "realm", and will have to be reused in the Apache configuration in the !AuthName directive:
     188<Location "/trac/login">
     189  AuthType Digest
     190  AuthName "trac"
     191  AuthDigestDomain /trac
     192  AuthUserFile /somewhere/trac.htpasswd
     193  Require valid-user
     197For multiple environments, you can use the same `LocationMatch` as described with the previous method.
     199'''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.
     201Don't forget to activate the mod_auth_digest. For example, on a Debian 4.0r1 (etch) system:
     203  LoadModule auth_digest_module /usr/lib/apache2/modules/
     206See also the [ mod_auth_digest] documentation.
     208=== Using LDAP Authentication
     210Configuration for [ mod_ldap] authentication in Apache is more involved (httpd 2.2+ and OpenLDAP: slapd 2.3.19).
     2121. You need to load the following modules in Apache httpd.conf:
     214  LoadModule ldap_module modules/
     215  LoadModule authnz_ldap_module modules/
     2171. Your httpd.conf also needs to look something like:
     219<Location /trac/>
     220  # (if you're using it, mod_python specific settings go here)
     221  Order deny,allow
     222  Deny from all
     223  Allow from
     224  AuthType Basic
     225  AuthName "Trac"
     226  AuthBasicProvider "ldap"
     227  AuthLDAPURL "ldap://,dc=co,dc=ke?uid?sub?(objectClass=inetOrgPerson)"
     228  authzldapauthoritative Off
     229  Require valid-user
     2321. You can use the LDAP interface as a way to authenticate to a Microsoft Active Directory. Use the following as your LDAP URL:
     234  AuthLDAPURL "ldap://,DC=com?sAMAccountName?sub?(objectClass=user)"
     236 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:
     238  AuthLDAPBindDN
     239  AuthLDAPBindPassword "password"
     241 The whole section looks like:
     243<Location /trac/>
     244  # (if you're using it, mod_python specific settings go here)
     245  Order deny,allow
     246  Deny from all
     247  Allow from
     248  AuthType Basic
     249  AuthName "Trac"
     250  AuthBasicProvider "ldap"
     251  AuthLDAPURL "ldap://,DC=com?sAMAccountName?sub?(objectClass=user)"
     252  AuthLDAPBindDN
     253  AuthLDAPBindPassword "the_password"
     254  authzldapauthoritative Off
     255  # require valid-user
     256  Require ldap-group CN=Trac Users,CN=Users,DC=company,DC=com
     260Note 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.
     262Note 2: You can also require the user be a member of a certain LDAP group, instead of just having a valid login:
     264  Require ldap-group CN=Trac Users,CN=Users,DC=example,DC=com
     267See also:
     268 - [ mod_authnz_ldap], documentation for mod_authnz_ldap.   
     269 - [ mod_ldap], documentation for mod_ldap, which provides connection pooling and a shared cache.
     270 - [ TracHacks:LdapPlugin] for storing TracPermissions in LDAP.
     272=== Using SSPI Authentication
     274If 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:
     276<Location /trac/login>
     277  AuthType SSPI
     278  AuthName "Trac Login"
     279  SSPIAuth On
     280  SSPIAuthoritative On
     281  SSPIDomain MyLocalDomain
     282  SSPIOfferBasic On
     283  SSPIOmitDomain Off
     284  SSPIBasicPreferred On
     285  Require valid-user
     289Using 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.
     291Some common problems with SSPI authentication: [trac:#1055], [trac:#1168] and [trac:#3338].
     293See also [trac:TracOnWindows/Advanced].
     295=== Using CA !SiteMinder Authentication
     297Setup 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`:
     303The 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.
     305Also add a !LogOffUri parameter to the agent configuration, for example `/trac/logout`.
     307Then 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`:
     310def application(environ, start_request):
     311    # Set authenticated username on CA SiteMinder to REMOTE_USER variable
     312    # strip() is used to remove any spaces on the end of the string
     313    if 'HTTP_SM_USER' in environ:
     314        environ['REMOTE_USER'] = environ['HTTP_REMOTE_USER'].strip()
     315    ...
     318You do not need any Apache "Location" directives.
     320=== Example: Apache/mod_wsgi with Basic Authentication, Trac being at the root of a virtual host
     322Per the mod_wsgi documentation linked to above, here is an example Apache configuration that:
     323 - serves the Trac instance from a virtualhost subdomain
     324 - uses Apache basic authentication for Trac authentication.
     326If 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:
     328Create the htpasswd file:
     330cd /home/trac-for-my-proj/the-env
     331htpasswd -c htpasswd firstuser
     332### and add more users to it as needed:
     333htpasswd htpasswd seconduser
     336Keep the file above your document root for security reasons.
     338Create this file for example `/etc/apache2/sites-enabled/` on Ubuntu with the following content:
     341<Directory /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi>
     342  WSGIApplicationGroup %{GLOBAL}
     343  Order deny,allow
     344  Allow from all
     347<VirtualHost *:80>
     348  ServerName
     349  DocumentRoot /home/trac-for-my-proj/the-env/htdocs/
     350  WSGIScriptAlias / /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi
     351  <Location '/'>
     352    AuthType Basic
     353    AuthName "Trac"
     354    AuthUserFile /home/trac-for-my-proj/the-env/htpasswd
     355    Require valid-user
     356  </Location>
     361For subdomains to work you would probably also need to alter `/etc/hosts` and add A-Records to your host's DNS.
     363== Troubleshooting
     365=== Use a recent version
     367Please 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].
     369'''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
     371If 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.
     373=== Getting Trac to work nicely with SSPI and 'Require Group'
     375If 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'.
     377This WSGI script fixes that:
     379import os
     380import trac.web.main
     382os.environ['TRAC_ENV'] = '/usr/local/trac/mysite'
     383os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
     385def application(environ, start_response):
     386    if "\\" in environ['REMOTE_USER']:
     387        environ['REMOTE_USER'] = environ['REMOTE_USER'].split("\\", 1)[1]
     388    return trac.web.main.dispatch_request(environ, start_response)
     391=== Trac with PostgreSQL
     393When 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.
     395A 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.
     397But it is not necessary to edit the source of Trac. The following lines in `trac.wsgi` will also work:
     400import trac.db.postgres_backend
     401trac.db.postgres_backend.PostgreSQLConnection.poolable = False
     407import trac.db.mysql_backend
     408trac.db.mysql_backend.MySQLConnection.poolable = False
     411Now Trac drops the connection after serving a page and the connection count on the database will be kept low.
     413//This is not a recommended approach though. See also the notes at the bottom of the [ mod_wsgi's IntegrationWithTrac] wiki page.//
     415=== Missing Headers and Footers
     417If python optimizations are enabled, then headers and footers will not be rendered. An error will be raised in Trac 1.0.11 and later when optimizations are enabled.
     419In your WSGI configuration file, the `WSGIPythonOptimize` setting must be set to `0` (`1` or `2` will not work):
     422    WSGIPythonOptimize 0
     425On Ubuntu, the WSGI mod configuration is at `/etc/apache2/mods-enabled/wsgi.conf`.
     427The same issue is seen with `PythonOptimize On` in [TracModPython#Pagelayoutissues ModPython].
     429=== Other resources
     431For 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.
     434See also: TracGuide, TracInstall, [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]