en/glep/glep-0011.txt

GLEP: 11
Title: Web Application Installation
Version: $Revision: 1.4 $
Last-Modified: $Date: 2003/08/13 13:45:38 $
Author: Troy Dack <tad@gentoo.org>
Author: Stuart Herbert <stuart@gentoo.org>
Discussions-To: gentoo-dev@gentoo.org
Status: Accepted
Type: Standards Track
Content-Type: text/x-rst
Created: 02-August-2003
Post-History: 07-Aug-2003, 12-Aug-2003, 13-Aug-2003

Credits
=======

Based on comments posted to gentoo-dev mailing list [#WebAppPost1]_
[#WebAppPost2]_ [#WebAppPost3]_ by:

        Stuart Herbert <stuart at gentoo.org>, Max Kalika <max at gentoo.org>,
        Robin H.Johnson <robbat2 at gentoo.org> and others

Definitions
===========

        *Web Application*
                an application that requires a web server to function and interacts with
                the user via a browser

        *Web Application Instance*
                An apparent install of the Web Application that is served up via the
                webserver. There may be any number of instances per Web Application.
                This is a major use for web applications. Our Gentoo Zope setup
                already provides instances and can be used for some concepts on this
                matter.

        *Web Application Setup Program*
                A script similar in function to zope-config that sets up instances.

        *Document Root*
                a location in the file system that forms the main document tree visible from
                the web

Conventions
===========

        When describing the location of a directory in the file system it
        wil be shown *with* a trailing slash, eg::

                /foo/bar/

        When describing the location of a specific file (irrespective of any
        file extention) it will shown *with out* a trailing slash, eg::

                /foo/blah

Abstract
========

To define where and how web based applications should be installed by Gentoo.

Motivation
==========

Currently there is no standard defined regarding the installation of web
based applicaitons in Gentoo.  This leads to ebuild authors creating a
variety of methods to determine:

        * where the application should be installed
        * what user and permissions the application should be given
        * where any configuration files related to the application should be
          installed.

Due to a lack of standard install method configuration files are at
risk of being overwritten during upgrade, potentially causing system
administrators down tine as they have to reconfigure web applications
after an upgrade.

Rationale
=========

A discussion on the gentoo-dev mailing list [#WebAppPost1]_ raised the
following points regarding how Gentoo handles the installation of web based
applications:

        1. Gentoo installed web applications (eg: horde, phpbb, cacti,
           phpmysql) should not be installed in the Document Root of a web server.
        2. Web applications should not have their configuration files installed
           under the Document Root of a web server.

                i. Web Application must be slotted by their full version numbers to
                   further avoid downtime when true configuration changes are required.

        3. Web applications should not be owned by the same user as the web server.
        4. It should be easily possible to have multiple instances of a web
           application without any duplication of source files.
        5. It should be immediately apparent how to control instances of a web
           application.

Implementation
==============

Max Kalika <max at gentoo.org> stated that he has a preliminary eclass that
implements a good deal of this GLEP.

Stuart Herbert <stuart at gentoo.org> has committed::

        webapp-apache.eclass

to CVS, this is a stop-gap measure whilst this GLEP is being finalised.


1. Web Server
-------------

A common default web server should be selected.  Selection of a default web 
server will help to reduce the number of bugs that are reported.

Given the popularity of the Apache web server it is suggested that Apache be 
selected as the Gentoo default web server.

The Virtual Host Configuration tool (see below) will transparently support
different web servers, thus enabling web applications to be installed on a 
Gentoo system irrespective of the installed web server.

1.1 Default Document Root
'''''''''''''''''''''''''

The current default Document Root for Gentoo is /home/httpd/, this is
unsuitable for a couple of reasons:

        * /home/ may be exported via nfs to numerous other hosts, it is not
          acceptable to share publically accessible files with numerous hosts.

        * there is a potential (all be it small) for a user name clash

To ensure the greatest flexibility when installing applications the following
*Document Root* locations are to be used:

        * For single host installations::

                /var/www/localhost/

        * For multiple virtual host installations::

                /var/www/<fully qualified domain name>/

                eg:
                        /var/www/www.gentoo.org/

Additionally the chosen location ( /var/www/ ) appears to be becoming a defacto
standard for Linux distributions.

1.2 Apache 2
''''''''''''

All web application .ebuilds will honour any USE flags that are intended to
add support for Apache 2 as well as supporting Apache 1 installations.

2. Application Installation
---------------------------

The current accepted standard Document Root in Gentoo is /home/httpd.  The
discussion suggest that this is not the best location to install web based
applications.

2.1 Application SLOTs
'''''''''''''''''''''

All ebuilds are to set the SLOT variable as follows::

        SLOT="${PV}"

Setting the SLOT variable as shown will enable different versions of the same
web application to be served concurrently by one server.

2.2 Installation Paths
''''''''''''''''''''''

Web applications should be installed outside of the Document Root using the following
defaults:

        * for files to be served to clients::

                /usr/share/webapps/${PF}/htdocs/

                /usr/share/webapps/${PF}/cgi-bin/

        * install *site default* configuration files in::

                /etc/webapps/${PF}/

        * for documentation files (not served to clients)::

                /usr/share/doc/${PF}/

3. Virtual Host Support
-----------------------

The ability to easily configure and administer multiple virtual hosts is a
must.

3.1 New "vhost" USE Flag
''''''''''''''''''''''''

To enable support for multiple virtual host installations a new USE flag is
to be added to Portage. The use flag will be::

        vhost

When *vhost* is _set_ the installation location and configuration for the web
application will be effected, see below for more details.

3.2 VHost Configuration Tool
''''''''''''''''''''''''''''

To assist administration of multiple virtual hosts a "VHost Configuration Tool"
needs to be developed and implemented.  Initial discussion regarding the VHost
Config tool and proposed usage can be found at http://article.gmane.org/gmane.linux.gentoo.devel/10874.

It's the job of the VHost Config toolset to make a local instance of the web
application run under a specific web server.

The VHost Configuration Utility will need to be a seperate package, maintained by Gentoo.

Web Server .ebuilds will require the VHost Config tool as a dependency (DEPEND).

`Bug #26293`_ will be used to track the initial progress of the VHost
Configuration Tool.

.. _Bug #26293: http://bugs.gentoo.org/show_bug.cgi?id=26293


The vhost-config must do three main things:

        - creates directories (copies a skeleton directory for the most part).
        - create web server vhost config files.
        - HUP web server so it reads in the new config without stopping.

Initially the VHost Config tool should provide support for the Apache web
server.  As the tool matures support for other web servers can be added.

3.3 Single Host Installation
''''''''''''''''''''''''''''

For single host installations the .ebuild will make the required
configurations changes and symlinks using the VHost Config tool to ensure
that the web application is available to be served from::

        /var/www/localhost/htdocs/${PF}/

In this case it may be feasible for the VHost Config tool to simply symlink the
directories from /usr/share/webapps/${PF}/ as is appropriate.

3.4 Virtual Host Installation
'''''''''''''''''''''''''''''

For installations that support multiple virtual hosts the .ebuild will
install the web application into the default location and then leave configuration
to the user through the VHost Config tool.

In this case the web application files will be copied from
/usr/share/webapps/${PF}/ to /var/www/<FQDN>/ by the VHost Config tool.

3.5 Configuration Files
'''''''''''''''''''''''

As stated above web application *site default* configuration files are to be
installed into::

        /etc/webapps/${PF}/

The files in this directory are then copied (not symlinked!) by the VHost
Config tool to the Document Root for each instance of the app that is installed.

This will require the VHost Config toolset to emulate Portage's CONFIG_PROTECT
behaviour for the web applications.

4. Application Permissions
--------------------------

Installing web applications and giving the web server ownership of the files
is a security risk.  This can possibly lead to application configuration
files being accessed by unwanted third parties.

All web applications should be owned by *root* unless the application
absolutely requires write access to its installation directories at execution
time.

Backwards Compatibility
=======================

There may be some issues regarding compatibility with existing installs of
web applications.  This is particularly true if the default Document Root is
moved from what is accepted as the current standard (/home/httpd).

The main issues are:
        * transition of existing configuration files to the
          /etc/webapps/${PF}/ directory.
        * modification/reconfiguration of applications so that they
          are aware of the location of configuration files.
        * creating the VHost Config toolset to enable installation and
          configuration of web applications irrespective of web server.


References
==========

.. [#WebAppPost1] http://article.gmane.org/gmane.linux.gentoo.devel/10411
.. [#WebAppPost2] http://news.gmane.org/onethread.php?group=gmane.linux.gentoo.devel&root=%3C1059843010.5023.80.camel%40carbon.internal.lan%3E
.. [#WebAppPost3] http://news.gmane.org/onethread.php?group=gmane.linux.gentoo.devel&root=%3C86960000.1060038977%40valkyrie.lsit.ucsb.edu%3E

Copyright
=========

This document has been placed in the public domain.
1	GLEP: 11
2	Title: Web Application Installation
3	Version: $Revision: 1.4 $
4	Last-Modified: $Date: 2003/08/13 13:45:38 $
5	Author: Troy Dack <tad@gentoo.org>
6	Author: Stuart Herbert <stuart@gentoo.org>
7	Discussions-To: gentoo-dev@gentoo.org
8	Status: Accepted
9	Type: Standards Track
10	Content-Type: text/x-rst
11	Created: 02-August-2003
12	Post-History: 07-Aug-2003, 12-Aug-2003, 13-Aug-2003
13
14	Credits
15	=======
16
17	Based on comments posted to gentoo-dev mailing list [#WebAppPost1]_
18	[#WebAppPost2]_ [#WebAppPost3]_ by:
19
20	Stuart Herbert <stuart at gentoo.org>, Max Kalika <max at gentoo.org>,
21	Robin H.Johnson <robbat2 at gentoo.org> and others
22
23	Definitions
24	===========
25
26	Web Application
27	an application that requires a web server to function and interacts with
28	the user via a browser
29
30	Web Application Instance
31	An apparent install of the Web Application that is served up via the
32	webserver. There may be any number of instances per Web Application.
33	This is a major use for web applications. Our Gentoo Zope setup
34	already provides instances and can be used for some concepts on this
35	matter.
36
37	Web Application Setup Program
38	A script similar in function to zope-config that sets up instances.
39
40	Document Root
41	a location in the file system that forms the main document tree visible from
42	the web
43
44	Conventions
45	===========
46
47	When describing the location of a directory in the file system it
48	wil be shown with a trailing slash, eg::
49
50	/foo/bar/
51
52	When describing the location of a specific file (irrespective of any
53	file extention) it will shown with out a trailing slash, eg::
54
55	/foo/blah
56
57	Abstract
58	========
59
60	To define where and how web based applications should be installed by Gentoo.
61
62	Motivation
63	==========
64
65	Currently there is no standard defined regarding the installation of web
66	based applicaitons in Gentoo. This leads to ebuild authors creating a
67	variety of methods to determine:
68
69	* where the application should be installed
70	* what user and permissions the application should be given
71	* where any configuration files related to the application should be
72	installed.
73
74	Due to a lack of standard install method configuration files are at
75	risk of being overwritten during upgrade, potentially causing system
76	administrators down tine as they have to reconfigure web applications
77	after an upgrade.
78
79	Rationale
80	=========
81
82	A discussion on the gentoo-dev mailing list [#WebAppPost1]_ raised the
83	following points regarding how Gentoo handles the installation of web based
84	applications:
85
86	1. Gentoo installed web applications (eg: horde, phpbb, cacti,
87	phpmysql) should not be installed in the Document Root of a web server.
88	2. Web applications should not have their configuration files installed
89	under the Document Root of a web server.
90
91	i. Web Application must be slotted by their full version numbers to
92	further avoid downtime when true configuration changes are required.
93
94	3. Web applications should not be owned by the same user as the web server.
95	4. It should be easily possible to have multiple instances of a web
96	application without any duplication of source files.
97	5. It should be immediately apparent how to control instances of a web
98	application.
99
100	Implementation
101	==============
102
103	Max Kalika <max at gentoo.org> stated that he has a preliminary eclass that
104	implements a good deal of this GLEP.
105
106	Stuart Herbert <stuart at gentoo.org> has committed::
107
108	webapp-apache.eclass
109
110	to CVS, this is a stop-gap measure whilst this GLEP is being finalised.
111
112
113	1. Web Server
114	-------------
115
116	A common default web server should be selected. Selection of a default web
117	server will help to reduce the number of bugs that are reported.
118
119	Given the popularity of the Apache web server it is suggested that Apache be
120	selected as the Gentoo default web server.
121
122	The Virtual Host Configuration tool (see below) will transparently support
123	different web servers, thus enabling web applications to be installed on a
124	Gentoo system irrespective of the installed web server.
125
126	1.1 Default Document Root
127	'''''''''''''''''''''''''
128
129	The current default Document Root for Gentoo is /home/httpd/, this is
130	unsuitable for a couple of reasons:
131
132	* /home/ may be exported via nfs to numerous other hosts, it is not
133	acceptable to share publically accessible files with numerous hosts.
134
135	* there is a potential (all be it small) for a user name clash
136
137	To ensure the greatest flexibility when installing applications the following
138	Document Root locations are to be used:
139
140	* For single host installations::
141
142	/var/www/localhost/
143
144	* For multiple virtual host installations::
145
146	/var/www/<fully qualified domain name>/
147
148	eg:
149	/var/www/www.gentoo.org/
150
151	Additionally the chosen location ( /var/www/ ) appears to be becoming a defacto
152	standard for Linux distributions.
153
154	1.2 Apache 2
155	''''''''''''
156
157	All web application .ebuilds will honour any USE flags that are intended to
158	add support for Apache 2 as well as supporting Apache 1 installations.
159
160	2. Application Installation
161	---------------------------
162
163	The current accepted standard Document Root in Gentoo is /home/httpd. The
164	discussion suggest that this is not the best location to install web based
165	applications.
166
167	2.1 Application SLOTs
168	'''''''''''''''''''''
169
170	All ebuilds are to set the SLOT variable as follows::
171
172	SLOT="${PV}"
173
174	Setting the SLOT variable as shown will enable different versions of the same
175	web application to be served concurrently by one server.
176
177	2.2 Installation Paths
178	''''''''''''''''''''''
179
180	Web applications should be installed outside of the Document Root using the following
181	defaults:
182
183	* for files to be served to clients::
184
185	/usr/share/webapps/${PF}/htdocs/
186
187	/usr/share/webapps/${PF}/cgi-bin/
188
189	* install site default configuration files in::
190
191	/etc/webapps/${PF}/
192
193	* for documentation files (not served to clients)::
194
195	/usr/share/doc/${PF}/
196
197	3. Virtual Host Support
198	-----------------------
199
200	The ability to easily configure and administer multiple virtual hosts is a
201	must.
202
203	3.1 New "vhost" USE Flag
204	''''''''''''''''''''''''
205
206	To enable support for multiple virtual host installations a new USE flag is
207	to be added to Portage. The use flag will be::
208
209	vhost
210
211	When vhost is _set_ the installation location and configuration for the web
212	application will be effected, see below for more details.
213
214	3.2 VHost Configuration Tool
215	''''''''''''''''''''''''''''
216
217	To assist administration of multiple virtual hosts a "VHost Configuration Tool"
218	needs to be developed and implemented. Initial discussion regarding the VHost
219	Config tool and proposed usage can be found at http://article.gmane.org/gmane.linux.gentoo.devel/10874.
220
221	It's the job of the VHost Config toolset to make a local instance of the web
222	application run under a specific web server.
223
224	The VHost Configuration Utility will need to be a seperate package, maintained by Gentoo.
225
226	Web Server .ebuilds will require the VHost Config tool as a dependency (DEPEND).
227
228	`Bug #26293`_ will be used to track the initial progress of the VHost
229	Configuration Tool.
230
231	.. _Bug #26293: http://bugs.gentoo.org/show_bug.cgi?id=26293
232
233
234	The vhost-config must do three main things:
235
236	- creates directories (copies a skeleton directory for the most part).
237	- create web server vhost config files.
238	- HUP web server so it reads in the new config without stopping.
239
240	Initially the VHost Config tool should provide support for the Apache web
241	server. As the tool matures support for other web servers can be added.
242
243	3.3 Single Host Installation
244	''''''''''''''''''''''''''''
245
246	For single host installations the .ebuild will make the required
247	configurations changes and symlinks using the VHost Config tool to ensure
248	that the web application is available to be served from::
249
250	/var/www/localhost/htdocs/${PF}/
251
252	In this case it may be feasible for the VHost Config tool to simply symlink the
253	directories from /usr/share/webapps/${PF}/ as is appropriate.
254
255	3.4 Virtual Host Installation
256	'''''''''''''''''''''''''''''
257
258	For installations that support multiple virtual hosts the .ebuild will
259	install the web application into the default location and then leave configuration
260	to the user through the VHost Config tool.
261
262	In this case the web application files will be copied from
263	/usr/share/webapps/${PF}/ to /var/www/<FQDN>/ by the VHost Config tool.
264
265	3.5 Configuration Files
266	'''''''''''''''''''''''
267
268	As stated above web application site default configuration files are to be
269	installed into::
270
271	/etc/webapps/${PF}/
272
273	The files in this directory are then copied (not symlinked!) by the VHost
274	Config tool to the Document Root for each instance of the app that is installed.
275
276	This will require the VHost Config toolset to emulate Portage's CONFIG_PROTECT
277	behaviour for the web applications.
278
279	4. Application Permissions
280	--------------------------
281
282	Installing web applications and giving the web server ownership of the files
283	is a security risk. This can possibly lead to application configuration
284	files being accessed by unwanted third parties.
285
286	All web applications should be owned by root unless the application
287	absolutely requires write access to its installation directories at execution
288	time.
289
290	Backwards Compatibility
291	=======================
292
293	There may be some issues regarding compatibility with existing installs of
294	web applications. This is particularly true if the default Document Root is
295	moved from what is accepted as the current standard (/home/httpd).
296
297	The main issues are:
298	* transition of existing configuration files to the
299	/etc/webapps/${PF}/ directory.
300	* modification/reconfiguration of applications so that they
301	are aware of the location of configuration files.
302	* creating the VHost Config toolset to enable installation and
303	configuration of web applications irrespective of web server.
304
305
306	References
307	==========
308
309	.. [#WebAppPost1] http://article.gmane.org/gmane.linux.gentoo.devel/10411
310	.. [#WebAppPost2] http://news.gmane.org/onethread.php?group=gmane.linux.gentoo.devel&root=%3C1059843010.5023.80.camel%40carbon.internal.lan%3E
311	.. [#WebAppPost3] http://news.gmane.org/onethread.php?group=gmane.linux.gentoo.devel&root=%3C86960000.1060038977%40valkyrie.lsit.ucsb.edu%3E
312
313	Copyright
314	=========
315
316	This document has been placed in the public domain.