Changes between Initial Version and Version 1 of TracModWSGI

Oct 23, 2015, 12:16:58 PM (6 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 just 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
     22In its simplest form, the script could be:
     25import os
     27os.environ['TRAC_ENV'] = '/usr/local/trac/mysite'
     28os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
     30import trac.web.main
     31application = trac.web.main.dispatch_request
     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`.
     36On Windows:
     37 - If run under the user's session, the Python Egg cache can be found in `%AppData%\Roaming`, for example:
     39os.environ['PYTHON_EGG_CACHE'] = r'C:\Users\Administrator\AppData\Roaming\Python-Eggs'
     41 - If run under a Window service, you should create a directory for Python Egg cache:
     43os.environ['PYTHON_EGG_CACHE'] = r'C:\Trac-Python-Eggs'
     46=== A more elaborate script
     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.
     50To solve this problem, use the following `.wsgi` file instead:
     52import os
     54os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
     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)
     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.
     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:
     67import site
     71Change it according to the path you installed the Trac libs at.
     73== Mapping requests to the script
     75After preparing your .wsgi script, add the following to your Apache configuration file, typically `httpd.conf`:
     78WSGIScriptAlias /trac /usr/local/trac/mysite/apache/mysite.wsgi
     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>
     94Here, the script is in a subdirectory of the Trac environment.
     96If you followed the directions [TracInstall#cgi-bin Generating the Trac cgi-bin directory], your Apache configuration file should look like following:
     99WSGIScriptAlias /trac /usr/share/trac/cgi-bin/trac.wsgi
     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>
     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.
     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):
     120def application(environ, start_response):
     121        start_response('200 OK',[('Content-type','text/html')])
     122        return ['<html><body>Hello World!</body></html>']
     125For more information about using the mod_wsgi specific directives, see the [ mod_wsgi's wiki] and more specifically the [ IntegrationWithTrac] page.
     127== Configuring Authentication
     129The following sections describe different methods for setting up authentication. See also [ Authentication, Authorization and Access Control] in the Apache guide.
     131=== Using Basic Authentication
     133The simplest way to enable authentication with Apache is to create a password file. Use the `htpasswd` program as follows:
     135$ htpasswd -c /somewhere/trac.htpasswd admin
     136New password: <type password>
     137Re-type new password: <type password again>
     138Adding password for user admin
     141After the first user, you don't need the "-c" option anymore:
     143$ htpasswd /somewhere/trac.htpasswd john
     144New password: <type password>
     145Re-type new password: <type password again>
     146Adding password for user john
     149  ''See the man page for `htpasswd` for full documentation.''
     151After you've created the users, you can set their permissions using TracPermissions.
     153Now, you need to enable authentication against the password file in the Apache configuration:
     155<Location "/trac/login">
     156  AuthType Basic
     157  AuthName "Trac"
     158  AuthUserFile /somewhere/trac.htpasswd
     159  Require valid-user
     163If you are hosting multiple projects, you can use the same password file for all of them:
     165<LocationMatch "/trac/[^/]+/login">
     166  AuthType Basic
     167  AuthName "Trac"
     168  AuthUserFile /somewhere/trac.htpasswd
     169  Require valid-user
     172Note that neither a file nor a directory named 'login' needs to exist.[[BR]]
     173See also the [ mod_auth_basic] documentation.
     175=== Using Digest Authentication
     177For better security, it is recommended that you either enable SSL or at least use the “digest” authentication scheme instead of “Basic”.
     179You have to create your `.htpasswd` file with the `htdigest` command instead of `htpasswd`, as follows:
     181$ htdigest -c /somewhere/trac.htpasswd trac admin
     184The "trac" parameter above is the "realm", and will have to be reused in the Apache configuration in the !AuthName directive:
     187<Location "/trac/login">
     188  AuthType Digest
     189  AuthName "trac"
     190  AuthDigestDomain /trac
     191  AuthUserFile /somewhere/trac.htpasswd
     192  Require valid-user
     196For multiple environments, you can use the same `LocationMatch` as described with the previous method.
     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. '''
     200Don't forget to activate the mod_auth_digest. For example, on a Debian 4.0r1 (etch) system:
     202  LoadModule auth_digest_module /usr/lib/apache2/modules/
     205See also the [ mod_auth_digest] documentation.
     207=== Using LDAP Authentication
     209Configuration for [ mod_ldap] authentication in Apache is more involved (httpd 2.2.x and OpenLDAP: slapd 2.3.19).
     2111. You need to load the following modules in Apache httpd.conf:
     213  LoadModule ldap_module modules/
     214  LoadModule authnz_ldap_module modules/
     2161. Your httpd.conf also needs to look something like:
     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
     223  AuthType Basic
     224  AuthName "Trac"
     225  AuthBasicProvider "ldap"
     226  AuthLDAPURL "ldap://,dc=co,dc=ke?uid?sub?(objectClass=inetOrgPerson)"
     227  authzldapauthoritative Off
     228  Require valid-user
     2311. You can use the LDAP interface as a way to authenticate to a Microsoft Active Directory. Use the following as your LDAP URL:
     233  AuthLDAPURL "ldap://,DC=com?sAMAccountName?sub?(objectClass=user)"
     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:
     237  AuthLDAPBindDN
     238  AuthLDAPBindPassword "password"
     240 The whole section looks like:
     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
     247  AuthType Basic
     248  AuthName "Trac"
     249  AuthBasicProvider "ldap"
     250  AuthLDAPURL "ldap://,DC=com?sAMAccountName?sub?(objectClass=user)"
     251  AuthLDAPBindDN
     252  AuthLDAPBindPassword "the_password"
     253  authzldapauthoritative Off
     254  # require valid-user
     255  Require ldap-group CN=Trac Users,CN=Users,DC=company,DC=com
     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.
     261Note 2: You can also require the user be a member of a certain LDAP group, instead of just having a valid login:
     263  Require ldap-group CN=Trac Users,CN=Users,DC=example,DC=com
     266See also:
     267 - [ mod_authnz_ldap], documentation for mod_authnz_ldap.   
     268 - [ mod_ldap], documentation for mod_ldap, which provides connection pooling and a shared cache.
     269 - [ TracHacks:LdapPlugin] for storing TracPermissions in LDAP.
     271=== Using SSPI Authentication
     273If 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:
     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
     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.
     290Some common problems with SSPI authentication: [trac:#1055], [trac:#1168] and [trac:#3338].
     292See also [trac:TracOnWindows/Advanced].
     294=== Using CA !SiteMinder Authentication
     295Setup CA !SiteMinder to protect your Trac login URL (e.g. /trac/login).  Then modify the trac.wsgi script generated using `trac-admin <env> deploy <dir>` to add the following lines, which extract the HTTP_SM_USER variable and set it to REMOTE_USER:
     298def application(environ, start_request):
     299    # Set authenticated username on CA SiteMinder to REMOTE_USER variable
     300    # strip() is used to remove any spaces on the end of the string
     301    if 'HTTP_SM_USER' in environ:
     302        environ['REMOTE_USER'] = environ['HTTP_SM_USER'].strip()
     303    ...
     306Note:  you do not need any Apache "Location" directives.
     308=== Using Apache authentication with the Account Manager plugin's Login form ===
     310To begin with, see the basic instructions for using the Account Manager plugin's [ Login module] and its [ HttpAuthStore authentication module].
     312'''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.
     314Here is an example (from the !HttpAuthStore link) using acct_mgr-0.4 for hosting a single project:
     317; be sure to enable the component
     318acct_mgr.http.HttpAuthStore = enabled
     321; configure the plugin to use a page that is secured with http authentication
     322authentication_url = /authFile
     323password_store = HttpAuthStore
     325This will generally be matched with an Apache config like:
     327<Location /authFile>
     328   …HTTP authentication configuration…
     329   Require valid-user
     332Note 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.
     334=== Example: Apache/mod_wsgi with Basic Authentication, Trac being at the root of a virtual host
     336Per the mod_wsgi documentation linked to above, here is an example Apache configuration that:
     337 - serves the Trac instance from a virtualhost subdomain
     338 - uses Apache basic authentication for Trac authentication.
     340If you want your Trac to be served from e.g. !, 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:
     342Create the htpasswd file:
     344cd /home/trac-for-my-proj/the-env
     345htpasswd -c htpasswd firstuser
     346### and add more users to it as needed:
     347htpasswd htpasswd seconduser
     349Keep the file above your document root for security reasons.
     351Create this file e.g. (ubuntu) `/etc/apache2/sites-enabled/` with the following content:
     354<Directory /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi>
     355  WSGIApplicationGroup %{GLOBAL}
     356  Order deny,allow
     357  Allow from all
     360<VirtualHost *:80>
     361  ServerName
     362  DocumentRoot /home/trac-for-my-proj/the-env/htdocs/
     363  WSGIScriptAlias / /home/trac-for-my-proj/the-deploy/cgi-bin/trac.wsgi
     364  <Location '/'>
     365    AuthType Basic
     366    AuthName "Trac"
     367    AuthUserFile /home/trac-for-my-proj/the-env/htpasswd
     368    Require valid-user
     369  </Location>
     374Note: for subdomains to work you would probably also need to alter `/etc/hosts` and add A-Records to your host's DNS.
     376== Troubleshooting
     378=== Use a recent version
     380Please 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].
     382''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''
     384If 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.
     386=== Getting Trac to work nicely with SSPI and 'Require Group'
     388If 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'.
     390This WSGI script 'fixes' that:
     392import os
     393import trac.web.main
     395os.environ['TRAC_ENV'] = '/usr/local/trac/mysite'
     396os.environ['PYTHON_EGG_CACHE'] = '/usr/local/trac/mysite/eggs'
     398def application(environ, start_response):
     399    if "\\" in environ['REMOTE_USER']:
     400        environ['REMOTE_USER'] = environ['REMOTE_USER'].split("\\", 1)[1]
     401    return trac.web.main.dispatch_request(environ, start_response)
     404=== Trac with PostgreSQL
     406When 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.
     408A 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.
     410But it is not necessary to edit the source of Trac. The following lines in `trac.wsgi` will also work:
     413import trac.db.postgres_backend
     414trac.db.postgres_backend.PostgreSQLConnection.poolable = False
     420import trac.db.mysql_backend
     421trac.db.mysql_backend.MySQLConnection.poolable = False
     424Now Trac drops the connection after serving a page and the connection count on the database will be kept low.
     426//This is not a recommended approach though. See also the notes at the bottom of the [ mod_wsgi's IntegrationWithTrac] wiki page.//
     428=== Other resources
     430For 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.
     433See also: TracGuide, TracInstall, [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]