Changes between Version 1 and Version 2 of TracModWSGI


Ignore:
Timestamp:
04/03/14 16:26:47 (11 years ago)
Author:
trac
Comment:

--

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  • TracModWSGI

    v1 v2  
    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 performances. 
     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 
     27=== A more elaborate script 
     28 
     29If 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.  
     30 
     31To solve this problem, use the following `.wsgi` file instead: 
     32{{{#!python 
    2633import os 
    2734 
    … …  
    3441}}} 
    3542 
    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 
     43For 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.  
     44 
     45If 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: 
     46 
     47{{{#!python 
    4248import site 
    4349site.addsitedir('/usr/local/trac/lib/python2.4/site-packages') 
    4450}}} 
    4551 
    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. 
     52Change it according to the path you installed the Trac libs at. 
     53 
     54=== Recommended `trac.wsgi` script 
     55 
     56A 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). 
     57 
     58 
     59== Mapping requests to the script 
     60 
     61After you've done preparing your .wsgi script, add the following to your Apache configuration file (`httpd.conf` for example). 
    4962 
    5063{{{ 
    … …  
    5871}}} 
    5972 
    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 {{{ 
     73Here, the script is in a subdirectory of the Trac environment. 
     74 
     75If you followed the directions [http://trac.edgewall.org/wiki/TracInstall#cgi-bin Generating the Trac cgi-bin directory], your Apache configuration file should look like following: 
     76 
     77{{{ 
     78WSGIScriptAlias /trac /usr/share/trac/cgi-bin/trac.wsgi 
     79 
     80<Directory /usr/share/trac/cgi-bin> 
     81    WSGIApplicationGroup %{GLOBAL} 
     82    Order deny,allow 
     83    Allow from all 
     84</Directory> 
     85}}} 
     86 
     87In 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. 
     88 
     89To 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): 
     90 
     91{{{#!python 
    6592def application(environ, start_response): 
    6693        start_response('200 OK',[('Content-type','text/html')]) 
    … …  
    6895}}} 
    6996 
    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: 
     97For 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. 
     98 
     99 
     100== Configuring Authentication 
     101 
     102We describe in the the following sections different methods for setting up authentication. 
     103 
     104See also [http://httpd.apache.org/docs/2.2/howto/auth.html Authentication, Authorization and Access Control] in the Apache guide. 
     105 
     106=== Using Basic Authentication === 
     107 
     108The simplest way to enable authentication with Apache is to create a password file. Use the `htpasswd` program to create the password file: 
     109{{{ 
     110$ htpasswd -c /somewhere/trac.htpasswd admin 
     111New password: <type password> 
     112Re-type new password: <type password again> 
     113Adding password for user admin 
     114}}} 
     115 
     116After the first user, you dont need the "-c" option anymore: 
     117{{{ 
     118$ htpasswd /somewhere/trac.htpasswd john 
     119New password: <type password> 
     120Re-type new password: <type password again> 
     121Adding password for user john 
     122}}} 
     123 
     124  ''See the man page for `htpasswd` for full documentation.'' 
     125 
     126After you've created the users, you can set their permissions using TracPermissions. 
     127 
     128Now, you'll need to enable authentication against the password file in the Apache configuration: 
     129{{{ 
     130<Location "/trac/login"> 
     131  AuthType Basic 
     132  AuthName "Trac" 
     133  AuthUserFile /somewhere/trac.htpasswd 
     134  Require valid-user 
     135</Location> 
     136}}} 
     137 
     138If you're hosting multiple projects you can use the same password file for all of them: 
     139{{{ 
     140<LocationMatch "/trac/[^/]+/login"> 
     141  AuthType Basic 
     142  AuthName "Trac" 
     143  AuthUserFile /somewhere/trac.htpasswd 
     144  Require valid-user 
     145</LocationMatch> 
     146}}} 
     147Note that neither a file nor a directory named 'login' needs to exist.[[BR]] 
     148See also the [http://httpd.apache.org/docs/2.2/mod/mod_auth_basic.html mod_auth_basic] documentation. 
     149 
     150=== Using Digest Authentication === 
     151 
     152For better security, it is recommended that you either enable SSL or at least use the “digest” authentication scheme instead of “Basic”.  
     153 
     154You'll have to create your `.htpasswd` file with the `htdigest` command instead of `htpasswd`, as follows: 
     155{{{ 
     156# htdigest -c /somewhere/trac.htpasswd trac admin 
     157}}} 
     158 
     159The "trac" parameter above is the "realm", and will have to be reused in the Apache configuration in the !AuthName directive: 
     160 
     161{{{ 
     162<Location "/trac/login"> 
     163 
     164    AuthType Digest 
     165    AuthName "trac" 
     166    AuthDigestDomain /trac 
     167    AuthUserFile /somewhere/trac.htpasswd 
     168    Require valid-user 
     169</Location> 
     170}}} 
     171 
     172For multiple environments, you can use the same `LocationMatch` as described with the previous method. 
     173 
     174Don't forget to activate the mod_auth_digest. For example, on a Debian 4.0r1 (etch) system: 
     175{{{ 
     176    LoadModule auth_digest_module /usr/lib/apache2/modules/mod_auth_digest.so 
     177}}} 
     178 
     179 
     180See also the [http://httpd.apache.org/docs/2.2/mod/mod_auth_digest.html mod_auth_digest] documentation. 
     181 
     182=== Using LDAP Authentication  
     183 
     184Configuration 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) 
     185 
     1861. You need to load the following modules in Apache httpd.conf 
     187{{{ 
     188LoadModule ldap_module modules/mod_ldap.so 
     189LoadModule authnz_ldap_module modules/mod_authnz_ldap.so 
     190}}} 
     191 
     1922. Your httpd.conf also needs to look something like: 
     193 
     194{{{ 
     195<Location /trac/> 
     196  # (if you're using it, mod_python specific settings go here) 
     197  Order deny,allow 
     198  Deny from all 
     199  Allow from 192.168.11.0/24 
     200  AuthType Basic 
     201  AuthName "Trac" 
     202  AuthBasicProvider "ldap" 
     203  AuthLDAPURL "ldap://127.0.0.1/dc=example,dc=co,dc=ke?uid?sub?(objectClass=inetOrgPerson)" 
     204  authzldapauthoritative Off 
     205  Require valid-user 
     206</Location> 
     207}}} 
     208 
     209 
     2103. You can use the LDAP interface as a way to authenticate to a Microsoft Active Directory: 
     211 
     212 
     213Use the following as your LDAP URL: 
     214{{{ 
     215    AuthLDAPURL "ldap://directory.example.com:3268/DC=example,DC=com?sAMAccountName?sub?(objectClass=user)" 
     216}}} 
     217 
     218You will also need to provide an account for Apache to use when checking 
     219credentials. As this password will be listed in plaintext in the 
     220config, you should be sure to use an account specifically for this task: 
     221{{{ 
     222    AuthLDAPBindDN ldap-auth-user@example.com 
     223    AuthLDAPBindPassword "password" 
     224}}} 
     225 
     226The whole section looks like: 
     227{{{ 
     228<Location /trac/> 
     229  # (if you're using it, mod_python specific settings go here) 
     230  Order deny,allow 
     231  Deny from all 
     232  Allow from 192.168.11.0/24 
     233  AuthType Basic 
     234  AuthName "Trac" 
     235  AuthBasicProvider "ldap" 
     236  AuthLDAPURL "ldap://adserver.company.com:3268/DC=company,DC=com?sAMAccountName?sub?(objectClass=user)" 
     237  AuthLDAPBindDN       ldap-auth-user@company.com 
     238  AuthLDAPBindPassword "the_password" 
     239  authzldapauthoritative Off 
     240  # require valid-user 
     241  require ldap-group CN=Trac Users,CN=Users,DC=company,DC=com 
     242</Location> 
     243}}} 
     244 
     245Note 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. 
     246 
     247Note 2: You can also require the user be a member of a certain LDAP group, instead of 
     248just having a valid login: 
     249{{{ 
     250    Require ldap-group CN=Trac Users,CN=Users,DC=example,DC=com 
     251}}} 
     252 
     253See also: 
     254  - [http://httpd.apache.org/docs/2.2/mod/mod_authnz_ldap.html mod_authnz_ldap], documentation for mod_authnz_ldap 
     255     
     256 - [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. 
     257 - [http://trac-hacks.org/wiki/LdapPlugin TracHacks:LdapPlugin] for storing TracPermissions in LDAP. 
     258 
     259=== Using SSPI Authentication 
     260 
     261If you are using Apache on Windows, you can use mod_auth_sspi to provide 
     262single-sign-on. Download the module from the !SourceForge [http://sourceforge.net/projects/mod-auth-sspi/ mod-auth-sspi project] and then add the 
     263following to your !VirtualHost: 
     264{{{ 
     265    <Location /trac/login> 
     266        AuthType SSPI 
     267        AuthName "Trac Login" 
     268        SSPIAuth On 
     269        SSPIAuthoritative On 
     270        SSPIDomain MyLocalDomain 
     271        SSPIOfferBasic On 
     272        SSPIOmitDomain Off 
     273        SSPIBasicPreferred On 
     274        Require valid-user 
     275    </Location> 
     276}}} 
     277 
     278Using the above, usernames in Trac will be of the form `DOMAIN\username`, so 
     279you may have to re-add permissions and such. If you do not want the domain to 
     280be part of the username, set `SSPIOmitDomain On` instead. 
     281 
     282Some common problems with SSPI authentication: [trac:#1055], [trac:#1168] and [trac:#3338]. 
     283 
     284See also [trac:TracOnWindows/Advanced]. 
     285 
     286=== Using Apache authentication with the Account Manager plugin's Login form === 
     287 
     288To 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]. 
     289 
     290'''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. 
     291 
     292Here is an example (from the !HttpAuthStore link) using acct_mgr-0.4 for hosting a single project: 
     293{{{ 
     294[components] 
     295; be sure to enable the component 
     296acct_mgr.http.HttpAuthStore = enabled 
     297 
     298[account-manager] 
     299; configure the plugin to use a page that is secured with http authentication 
     300authentication_url = /authFile 
     301password_store = HttpAuthStore 
     302}}} 
     303This will generally be matched with an Apache config like: 
     304{{{ 
     305<Location /authFile> 
     306   …HTTP authentication configuration… 
     307   Require valid-user 
     308</Location> 
     309}}} 
     310Note that '''authFile''' need not exist. See the !HttpAuthStore link above for examples where multiple Trac projects are hosted on a server. 
     311 
     312=== Example: Apache/mod_wsgi with Basic Authentication, Trac being at the root of a virtual host 
     313 
     314Per 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. 
     315 
     316 
     317If 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: 
     318 
     319Create the htpasswd file: 
    84320{{{ 
    85321cd /home/trac-for-my-proj/the-env 
    … …  
    88324htpasswd htpasswd seconduser 
    89325}}} 
    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: 
     326(keep the file above your document root for security reasons) 
     327 
     328Create this file e.g. (ubuntu) `/etc/apache2/sites-enabled/trac.my-proj.my-site.org.conf` with the following contents: 
    93329 
    94330{{{ 
    … …  
    113349}}} 
    114350 
    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' == 
     351Note: for subdomains to work you would probably also need to alter `/etc/hosts` and add A-Records to your host's DNS. 
     352 
     353 
     354== Troubleshooting 
     355 
     356=== Use a recent version 
     357 
     358Please 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]. 
     359 
     360''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'' 
     361 
     362If 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). 
     363 
     364=== Getting Trac to work nicely with SSPI and 'Require Group' === 
    134365If 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'. 
    135366 
    136367This WSGI script 'fixes' things, hope it helps: 
    137 {{{ 
     368{{{#!python 
    138369import os 
    139370import trac.web.main 
    … …  
    147378    return trac.web.main.dispatch_request(environ, start_response) 
    148379}}} 
     380 
     381 
     382=== Trac with PostgreSQL === 
     383 
     384When 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. 
     385 
     386A 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. 
     387 
     388But it's not necessary to edit the source of Trac, the following lines in `trac.wsgi` will also work: 
     389 
     390{{{ 
     391import trac.db.postgres_backend 
     392trac.db.postgres_backend.PostgreSQLConnection.poolable = False 
     393}}} 
     394 
     395or 
     396 
     397{{{ 
     398import trac.db.mysql_backend 
     399trac.db.mysql_backend.MySQLConnection.poolable = False 
     400}}} 
     401 
     402Now Trac drops the connection after serving a page and the connection count on the database will be kept minimal. 
     403 
     404//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.// 
     405 
     406=== Other resources 
     407 
     408For 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. 
     409 
     410 
    149411---- 
    150412See also:  TracGuide, TracInstall, [wiki:TracFastCgi FastCGI], [wiki:TracModPython ModPython], [trac:TracNginxRecipe TracNginxRecipe]