en/glep/glep-0049.txt

GLEP: 49
Title: Alternative Package Manager requirements
Version: $Revision: 2213 $
Last-Modified: $Date: 2006-05-19 12:58:14 +0200 (Fri, 19 May 2006) $
Author: Paul de Vrieze <pauldv@gentoo.org>,
Status: Draft
Type: Standards Track
Content-Type: text/x-rst
Created: 18-May-2006
Post-History: 20-May-2006


Abstract
========

This GLEP describes four classes of package managers. What the requirements for
them are, and what support they can receive.


Motivation
==========

To set a standard that package managers that seek gentoo project approval and
support should adhere to.


Rationale
=========

Currently portage is  showing its age. The  code of portage does not  seem to be
salvageable for new  versions. There are two known  alternative package managers
that claim a  level of portage compatibility. These  alternatives are `paludis`_
and `pkgcore`_.  Before these alternatives are developed further, a set of rules
should be created to level the  playing field and ensuring that decisions can be
made clearly.


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

Not a problem for this GLEP. There is no previous standard as the issue did not
exist before. This GLEP is to prevent future compatibility issues.


Categories of package managers
==============================

We distinguish four categories of package managers. While a package manager can
transition from one category to another, it can not be in two categories at the
same time. It can be in a state of transition though.

*Primary Package Manager*  
   There  is one primary  package manager.  Currently this  position is  held by
   portage.  The primary  package manager  is assigned  by the  council  and all
   packages in the official tree must be installable by a useable version of the
   primary package manager.

*Candidate Primary Package Managers*
   A candidate  Primary Package Manager does  aim, or show an  aim, at replacing
   the current primary package manager. At  a point where the package manager is
   deemed stable  a decision  must be made  whether this package  manager should
   become the  new primary package manager.  At that point  the `primary package
   manager transition phase`_ starts.

*Secondary Package Managers*
   A  secondary package  manager is  a package  manager that  coexists  with the
   primary package  manager, while  not aiming to  replace it.  Package managers
   that would fall into this category are:

   - Experimental package managers. Package managers  whose purpose it is to try
     out new features.

   - Focussed package  managers. For example  a package manager that  allows the
     use of rpm formatted binary packages would be an example.


*Third Party Package Managers*
   A third party  package manager is any package  manager that lacks recognition
   from gentoo as being in any other category. A third party package manager may
   or may not have a gentoo package, but is not supported beyond that.


Package manager requirements
============================

As  a  package  manager is  in  a  state  of  higher  support there  are  higher
requirements to it. The purpose of  these requirements is to ensure the unity of
the distribution and the package tree.  For this purpose it is needed that there
is only one primary package manager.


primary package manager requirements
------------------------------------

The primary package  manager is the package manager that  sets the standards for
the  tree. All  ebuilds  in the  tree  must function  with  the primary  package
manager. As  the primary package manager sets  the standard it does  not have to
maintain compatibility with other package managers.

The primary package manager does however have the responsibility that it must be
very stable.  The primary package  manager must maintain compatibility  with old
versions of itself  for extended periods of time. This  compatibilty time is set
by the council. The  suggested time would be one year from  the point that there
is a compatible stable version for all supported architectures.

Another compatibilty  requirement for the  primary package manager is  a limited
forward  compatibility.  It must  always  be  possible  to transition  from  the
unstable version of the primary package manager to a stable version. This may be
done either by first introducing reading compatibility for a new format and only
having write support  later. Another way would be the  provision of a conversion
tool that ensures that the on disk information maintained by the package manager
is supported by the stable package manager.

The primary package manager is maintained on official gentoo infrastructure,
under control of gentoo developers.


candidate primary package manager requirements
------------------------------------------------

A  candidate  primary  package  manager  aims to  replace  the  primary  package
manager.  The council  is responsible  for deciding  whether this  is  done. The
requirements are  there to ensure that  it is actually possible  to transition a
candidate primary package manager into the primary package manager.

First of all,  there must exist a  transition path. This means that  the on disk
data of  the primary package manager  can be used  by (or converted to  a format
usable by) the candidate primary package manager.

Second, there  must be a test  path. It must  be possible for the  developers to
test out  the candidate primary package  manager on their  working systems. This
means that  the transition path  must exist. This  also means that there  are no
serious obstacles for reverting to the current primary package manager.

Third, there  must exist an ebuild test  path.  It must be  possible for package
managers  to test  ebuilds in  one tree  for  both the  primary as  well as  the
candidate primary package manager. It is not an issue if this requires a special
mode for  the candidate primary  package manager. It  is not an issue  either if
compatibilty can be  achieved by unmerging the package  in the candidate primary
package manager.

Fourth, there must  be support. This means that the  package manager is actively
maintained  under  control  of  gentoo.  If  it  is  not  maintained  on  gentoo
infrastructure, the  means must be there  to move the package  manager, with its
change history, to gentoo infrastructure.  This means that it must be maintained
on a  gentoo supported versioning system,  or on a version  system whose history
can be converted to a gentoo supported versioning system.


secondary package manager requirements
--------------------------------------

A secondary package manager is a package manager that instead of directly aiming
at replacing  portage as  primary package manager.  As such a  secondary package
manager does not set  the standard on the tree, but follows  the standard set by
the primary package manager.

There are two  kinds of secondary package managers. The first  kind is formed by
those that do  not maintain their own installed package  database, but work with
the  package  database of  the  primary  package  manager. While  these  package
managers  can put  additional information  in the  database, these  entries must
remain compatible  with the  primary package managers.  Verification, reference,
and deinstallation by the primary package manager must remain functional.

The second  kind is  formed by  those package managers  that maintain  their own
package database,  or a package  database incompatible with the  primary package
manager. To ensure  the secondary role of these package  managers the support in
the tree for these package manager is provided along with restrictions.

The first restriction is that no packages in the tree must rely on the secondary
package  manager. While packages  may provide  a level  of support  (while being
compatible  with  the  primary  package  manager)  this  may  not  result  in  a
significant increase  of features.  If this were  allowed, this would  mean that
while they  technically work  with the primary  package manager, there  would be
significant incentive to  use the secondary package manager. As  the use of this
secondary  package manager  disallows the  paralel  use of  the primary  package
manager, this would result in users using the secondary package manager as their
primary package manager.

Users are allowed to make their own  choices. However by making the tree favor a
package manager that  is not the primary package manager, this  will lead to the
secondary package  manager becomming the  effective primary package  manager. As
this will be a decision by default  instead of a concious choice by the council,
this is an undesirable result.

There is  one exclusion for the restriction  of packages that only  work with or
have  significant  improvements with  the  secondary  package  manager. That  is
packages  that by  their  nature are  only  usable with  this secondary  package
manager.   An example would  be a  graphical frontend  to the  secondary package
manager.

If a secondary  package manager works along the primary  package manager, but by
itself does not have the capabilities  of becoming a primary package manager the
risks of choice by  default are lower. As a result, the  council could choose to
allow the inclusion of packages that work only or significantly better with this
secondary  package manager.  For example  at a  point where  there is  a stable,
functional, package  manager that  can handle RPM  format packages,  the council
could decide  to include these packages  directly in the tree,  instead of using
wrapper  scripts  for  those  packages   that  are  only  provided  in  the  RPM
format. Such a  decision does imply that the maintainers  of the primary package
manager must take this secondary package manager into account.


third party package manager requirements
----------------------------------------

A third party package manager is just  that. It is a package manager without any
support within gentoo. As there is no control by gentoo over the package manager
this means that there are no requirements on the package manager.

This complete  lack of control however  also translates to the  fact that gentoo
can  not  make  package  manager   specific  changes  to  support  this  package
manager. Package manager  specific means that it is  possible to request changes
that  make the  tree  more independent  of  the primary  package manager.  These
changes must however be agnostic of the package manager, and only make it easier
to have alternative package managers.


transition phases
=================

primary package manager transition phase
----------------------------------------

A  candidate primary package  manager can  be chosen  to become  primary package
manager. This  can only happen  by council decision.  This decision can  only be
made  when  the  candiate  primary  package  manager is  stable  on  all  stable
architectures. (all architectures except experimental ones).

After the  decision has been  made to replace  the primary package  manager, the
transition phase starts.  The use of  the old stable package manager must remain
supported  for a  period of  6 months.  This means  that core  packages  must be
installable  by this  package manager.  Further the  possibility to  convert the
system automatically to the new primary package manager must be available for at
least  18 months,  but  preferably  longer (enable  installing  the new  package
manager from the old one).

During the  transition phase packages are allowed  in the tree that  use the new
features of the  new primary package manager. While  backward compatibility with
the previous primary package manager  must be maintained a forward compatibility
is no longer needed.


Secondary package manager to candidate primary package manager transition
-------------------------------------------------------------------------

The  transition from  secondary  package manager  to  candidate primary  package
manager  is straightforward.  The  secondary package  manager  must satisfy  all
requirements  for  a  candidate  primary  package manager.  At  that  point  its
maintainers can announce that they  are changing the status to candidate primary
package manager.  This allows  a greater support  from gentoo in  achieving that
goal.


Third party to other transition
-------------------------------

When a third party package manager wants to transition into one of the other
categories (except primary package manager) it must satisfy all requirements for
that category.


References
==========

.. _paludis: http://paludis.berlios.de/
.. _pkgcore: http://gentooexperimental.org/~ferringb/bzr/pkgcore/
.. _Open Publication License: http://www.opencontent.org/openpub/


Copyright
=========

This document is copyright 2006 by Paul de Vrieze and licensed under the
`Open Publication License`_.


1	pauldv	1.1	GLEP: 49
2			Title: Alternative Package Manager requirements
3			Version: $Revision: 2213 $
4			Last-Modified: $Date: 2006-05-19 12:58:14 +0200 (Fri, 19 May 2006) $
5			Author: Paul de Vrieze <pauldv@gentoo.org>,
6			Status: Draft
7			Type: Standards Track
8			Content-Type: text/x-rst
9			Created: 18-May-2006
10			Post-History: 20-May-2006
11
12
13			Abstract
14			========
15
16			This GLEP describes four classes of package managers. What the requirements for
17			them are, and what support they can receive.
18
19
20			Motivation
21			==========
22
23			To set a standard that package managers that seek gentoo project approval and
24			support should adhere to.
25
26
27			Rationale
28			=========
29
30			Currently portage is showing its age. The code of portage does not seem to be
31			salvageable for new versions. There are two known alternative package managers
32			that claim a level of portage compatibility. These alternatives are `paludis`_
33			and `pkgcore`_. Before these alternatives are developed further, a set of rules
34			should be created to level the playing field and ensuring that decisions can be
35			made clearly.
36
37
38			Backwards Compatibility
39			=======================
40
41			Not a problem for this GLEP. There is no previous standard as the issue did not
42			exist before. This GLEP is to prevent future compatibility issues.
43
44
45			Categories of package managers
46			==============================
47
48			We distinguish four categories of package managers. While a package manager can
49			transition from one category to another, it can not be in two categories at the
50			same time. It can be in a state of transition though.
51
52			Primary Package Manager
53			There is one primary package manager. Currently this position is held by
54			portage. The primary package manager is assigned by the council and all
55			packages in the official tree must be installable by a useable version of the
56			primary package manager.
57
58			Candidate Primary Package Managers
59			A candidate Primary Package Manager does aim, or show an aim, at replacing
60			the current primary package manager. At a point where the package manager is
61			deemed stable a decision must be made whether this package manager should
62			become the new primary package manager. At that point the `primary package
63			manager transition phase`_ starts.
64
65			Secondary Package Managers
66			A secondary package manager is a package manager that coexists with the
67			primary package manager, while not aiming to replace it. Package managers
68			that would fall into this category are:
69
70			- Experimental package managers. Package managers whose purpose it is to try
71			out new features.
72
73			- Focussed package managers. For example a package manager that allows the
74			use of rpm formatted binary packages would be an example.
75
76
77			Third Party Package Managers
78			A third party package manager is any package manager that lacks recognition
79			from gentoo as being in any other category. A third party package manager may
80			or may not have a gentoo package, but is not supported beyond that.
81
82
83			Package manager requirements
84			============================
85
86			As a package manager is in a state of higher support there are higher
87			requirements to it. The purpose of these requirements is to ensure the unity of
88			the distribution and the package tree. For this purpose it is needed that there
89			is only one primary package manager.
90
91
92			primary package manager requirements
93			------------------------------------
94
95			The primary package manager is the package manager that sets the standards for
96			the tree. All ebuilds in the tree must function with the primary package
97			manager. As the primary package manager sets the standard it does not have to
98			maintain compatibility with other package managers.
99
100			The primary package manager does however have the responsibility that it must be
101			very stable. The primary package manager must maintain compatibility with old
102			versions of itself for extended periods of time. This compatibilty time is set
103			by the council. The suggested time would be one year from the point that there
104			is a compatible stable version for all supported architectures.
105
106			Another compatibilty requirement for the primary package manager is a limited
107			forward compatibility. It must always be possible to transition from the
108			unstable version of the primary package manager to a stable version. This may be
109			done either by first introducing reading compatibility for a new format and only
110			having write support later. Another way would be the provision of a conversion
111			tool that ensures that the on disk information maintained by the package manager
112			is supported by the stable package manager.
113
114			The primary package manager is maintained on official gentoo infrastructure,
115			under control of gentoo developers.
116
117
118			candidate primary package manager requirements
119			------------------------------------------------
120
121			A candidate primary package manager aims to replace the primary package
122			manager. The council is responsible for deciding whether this is done. The
123			requirements are there to ensure that it is actually possible to transition a
124			candidate primary package manager into the primary package manager.
125
126			First of all, there must exist a transition path. This means that the on disk
127			data of the primary package manager can be used by (or converted to a format
128			usable by) the candidate primary package manager.
129
130			Second, there must be a test path. It must be possible for the developers to
131			test out the candidate primary package manager on their working systems. This
132			means that the transition path must exist. This also means that there are no
133			serious obstacles for reverting to the current primary package manager.
134
135			Third, there must exist an ebuild test path. It must be possible for package
136			managers to test ebuilds in one tree for both the primary as well as the
137			candidate primary package manager. It is not an issue if this requires a special
138			mode for the candidate primary package manager. It is not an issue either if
139			compatibilty can be achieved by unmerging the package in the candidate primary
140			package manager.
141
142			Fourth, there must be support. This means that the package manager is actively
143			maintained under control of gentoo. If it is not maintained on gentoo
144			infrastructure, the means must be there to move the package manager, with its
145			change history, to gentoo infrastructure. This means that it must be maintained
146			on a gentoo supported versioning system, or on a version system whose history
147			can be converted to a gentoo supported versioning system.
148
149
150			secondary package manager requirements
151			--------------------------------------
152
153			A secondary package manager is a package manager that instead of directly aiming
154			at replacing portage as primary package manager. As such a secondary package
155			manager does not set the standard on the tree, but follows the standard set by
156			the primary package manager.
157
158			There are two kinds of secondary package managers. The first kind is formed by
159			those that do not maintain their own installed package database, but work with
160			the package database of the primary package manager. While these package
161			managers can put additional information in the database, these entries must
162			remain compatible with the primary package managers. Verification, reference,
163			and deinstallation by the primary package manager must remain functional.
164
165			The second kind is formed by those package managers that maintain their own
166			package database, or a package database incompatible with the primary package
167			manager. To ensure the secondary role of these package managers the support in
168			the tree for these package manager is provided along with restrictions.
169
170			The first restriction is that no packages in the tree must rely on the secondary
171			package manager. While packages may provide a level of support (while being
172			compatible with the primary package manager) this may not result in a
173			significant increase of features. If this were allowed, this would mean that
174			while they technically work with the primary package manager, there would be
175			significant incentive to use the secondary package manager. As the use of this
176			secondary package manager disallows the paralel use of the primary package
177			manager, this would result in users using the secondary package manager as their
178			primary package manager.
179
180			Users are allowed to make their own choices. However by making the tree favor a
181			package manager that is not the primary package manager, this will lead to the
182			secondary package manager becomming the effective primary package manager. As
183			this will be a decision by default instead of a concious choice by the council,
184			this is an undesirable result.
185
186			There is one exclusion for the restriction of packages that only work with or
187			have significant improvements with the secondary package manager. That is
188			packages that by their nature are only usable with this secondary package
189			manager. An example would be a graphical frontend to the secondary package
190			manager.
191
192			If a secondary package manager works along the primary package manager, but by
193			itself does not have the capabilities of becoming a primary package manager the
194			risks of choice by default are lower. As a result, the council could choose to
195			allow the inclusion of packages that work only or significantly better with this
196			secondary package manager. For example at a point where there is a stable,
197			functional, package manager that can handle RPM format packages, the council
198			could decide to include these packages directly in the tree, instead of using
199			wrapper scripts for those packages that are only provided in the RPM
200			format. Such a decision does imply that the maintainers of the primary package
201			manager must take this secondary package manager into account.
202
203
204			third party package manager requirements
205			----------------------------------------
206
207			A third party package manager is just that. It is a package manager without any
208			support within gentoo. As there is no control by gentoo over the package manager
209			this means that there are no requirements on the package manager.
210
211			This complete lack of control however also translates to the fact that gentoo
212			can not make package manager specific changes to support this package
213			manager. Package manager specific means that it is possible to request changes
214			that make the tree more independent of the primary package manager. These
215			changes must however be agnostic of the package manager, and only make it easier
216			to have alternative package managers.
217
218
219			transition phases
220			=================
221
222			primary package manager transition phase
223			----------------------------------------
224
225			A candidate primary package manager can be chosen to become primary package
226			manager. This can only happen by council decision. This decision can only be
227			made when the candiate primary package manager is stable on all stable
228			architectures. (all architectures except experimental ones).
229
230			After the decision has been made to replace the primary package manager, the
231			transition phase starts. The use of the old stable package manager must remain
232			supported for a period of 6 months. This means that core packages must be
233			installable by this package manager. Further the possibility to convert the
234			system automatically to the new primary package manager must be available for at
235			least 18 months, but preferably longer (enable installing the new package
236			manager from the old one).
237
238			During the transition phase packages are allowed in the tree that use the new
239			features of the new primary package manager. While backward compatibility with
240			the previous primary package manager must be maintained a forward compatibility
241			is no longer needed.
242
243
244			Secondary package manager to candidate primary package manager transition
245			-------------------------------------------------------------------------
246
247			The transition from secondary package manager to candidate primary package
248			manager is straightforward. The secondary package manager must satisfy all
249			requirements for a candidate primary package manager. At that point its
250			maintainers can announce that they are changing the status to candidate primary
251			package manager. This allows a greater support from gentoo in achieving that
252			goal.
253
254
255			Third party to other transition
256			-------------------------------
257
258			When a third party package manager wants to transition into one of the other
259			categories (except primary package manager) it must satisfy all requirements for
260			that category.
261
262
263			References
264			==========
265
266			.. _paludis: http://paludis.berlios.de/
267			.. _pkgcore: http://gentooexperimental.org/~ferringb/bzr/pkgcore/
268			.. _Open Publication License: http://www.opencontent.org/openpub/
269
270
271			Copyright
272			=========
273
274			This document is copyright 2006 by Paul de Vrieze and licensed under the
275			`Open Publication License`_.
276
277