A meta package is a Debian package which contains:
/etc/cdd/<cdd>/menu/<pkg-name>
debconf
questions or pre-seeding (optional)
cfengine
scripts (optional)
<cdd>-common
Meta packages are small packages with nearly no contents. The main feature of
this type of packages is their dependencies from other packages. The naming
scheme of meta packages <cdd>-<task> where
<cdd> stands for the shortcut of a Custom Debian Distribution,
i.e. junior
for Debian-Jr or med
for Debian-Med, and
<task> means the certain task inside the Custom Debian
Distribution.
Examples:
junior-puzzle
debian-edu-config
med-bio
When using meta packages no research for available software inside Debian is necessary. It would be not acceptable for normal users to browse the descriptions of the whole list of the 10000 packages in Debian. So meta packages are an easy method to help users to find the packages that are interesting for their work quickly.
If the author of the meta package decided to include packages with similar functionality an easy comparison between software covering the same task is possible.
Moreover the installation of a meta package ensures that no package which is necessary for the intended task can be removed without explicit notice that also the meta package has to be removed.
By defining conflicts to some other packages inside the meta package it is possible to ensure that a package which might conflict for some reasons for the intended task can not be installed at the same time as the meta package is installed.
All in all meta packages enable an easy installation from scratch and keep the effort for administration low.
Besides the simplification of installing relevant packages by dependencies
inside meta packages these might contain special configuration for the intended
task. This might either be accomplished by pre-feeding debconf
questions or by modifying configuration files in a postinst
script. It has to be ensured that no changes which have been done manually by
the administrator will be changed by this procedure. So to say the
postinst
script takes over the role of a local administrator.
A "traditional" weakness of Free Software projects is missing
documentation. To fix this Custom Debian Distributions try to provide relevant
documentation to help users to solve their problems. This can be done by
building *-doc
of existing documentation, writing extra
documentation like manpages etc. This complies with the statement that Custom
Debian Distributions are focussed to interests of specialised users who have a
big need for good documentation in their native language.
Thus translation is a very important thing to make programs more useful for the
target user group. Debian has established a Debian Description Translation
Project
which has the goal to translate package descriptions. There
are good chances to use this system also for other types of documentation which
might be a great help for Custom Debian Distributions.
In short: There are no special tools available to handle meta packages nicely. But there eare some tricks which might help for the moment.
apt-cache
apt-cache
is useful to search for relevant keywords in
package descriptions. So you could search for a certain keyword connected to
your topic (for instance "med") and combine it
reasonably with grep
:
~> apt-cache search med | grep '^med-' med-bio - Debian-Med micro-biology packages med-common-dev - Debian-Med Project common files for developing meta packages med-dent - Debian-Med package for dental practice client med-doc - Debian-Med documentation packages med-imaging - Debian-Med imaging packages med-imaging-dev - Debian-Med packages for medical image development med-tools - Debian-Med several tools med-bio-contrib - Debian-Med micro-biology packages (contrib and non-free) med-common - Debian-Med Project common package med-cms - Debian-Med content management systems
This is not really straightforward currently and absolutely unacceptable for end users.
grep-dctrl
grep-dctrl
is a grep for Debian package information
which is helpful to find out something about packages matching a certain
pattern:
~> grep-dctrl ': med-' /var/lib/dpkg/available | grep -v '^[SIMAVF]' | grep -v '^Pri' Package: med-imaging Depends: paul, ctsim, ctn, minc-tools, medcon, xmedcon, med-common Description: Debian-Med imaging packages Package: med-dent Depends: debianutils (>= 2.6.2), mozilla-browser | www-browser, debconf (>= 0.5), med-common Description: Debian-Med package for dental practice client Package: med-bio Depends: bioperl, blast2, bugsx, fastdnaml, fastlink, garlic, hmmer, ncbi-tools-bin, ncbi-tools-x11, njplot, pymol, rasmol, readseq, tree-puzzle, med-common Description: Debian-Med micro-biology packages Package: med-common Depends: adduser, debconf (>= 0.5), menu Description: Debian-Med Project common package Package: med-common-dev Depends: debconf (>= 0.5) Description: Debian-Med Project common files for developing meta packages Package: med-tools Depends: mencal, med-common Description: Debian-Med several tools Package: med-doc Depends: doc-linux-html | doc-linux-text, resmed-doc, med-common, galeon | www-browser Description: Debian-Med documentation packages Package: med-cms Depends: zope-zms Description: Debian-Med content management systems Package: med-imaging-dev Depends: libgtkimreg-dev, ctn-dev, libminc0-dev, libmdc2-dev, med-common Description: Debian-Med packages for medical image development Package: med-bio-contrib Depends: clustalw | clustalw-mpi, clustalx, molphy, phylip, seaview, treetool, med-common Description: Debian-Med micro-biology packages (contrib and non-free)
This is as well as the apt-cache
example also a bit
cryptic and either not acceptable for end users.
auto-apt
auto-apt
is really cool if you are running a computer
which was installed from scratch in a hurry and are sitting on a booth for some
demonstration purpose. If you had no time to install all stuff you wanted to
demonstrate just start auto-apt
in the following manner and you
will never face some missing files or programs ...
~> sudo auto-apt update put: 880730 files, 1074158 entries put: 903018 files, 1101981 entries ~> auto-apt -x -y run Entering auto-apt mode: /bin/bash Exit the command to leave auto-apt mode. bash-2.05b$ less /usr/share/doc/med-bio/copyright Reading Package Lists... Done Building Dependency Tree... Done The following extra packages will be installed: bugsx fastlink readseq The following NEW packages will be installed: bugsx fastlink med-bio readseq 0 packages upgraded, 4 newly installed, 0 to remove and 183 not upgraded. Need to get 0B/1263kB of archives. After unpacking 2008kB will be used. Reading changelogs... Done Selecting previously deselected package bugsx. (Reading database ... 133094 files and directories currently installed.) Unpacking bugsx (from .../b/bugsx/bugsx_1.08-6_i386.deb) ... Selecting previously deselected package fastlink. Unpacking fastlink (from .../fastlink_4.1P-fix81-2_i386.deb) ... Selecting previously deselected package med-bio. Unpacking med-bio (from .../med-bio_0.4-1_all.deb) ... Setting up bugsx (1.08-6) ... Setting up fastlink (4.1P-fix81-2) ... Setting up med-bio (0.4-1) ... localepurge: checking for new locale files ... localepurge: processing locale files ... localepurge: processing man pages ... This package is Copyright 2002 by Andreas Tille <tille@debian.org> This software is licensed under the GPL. On Debian systems, the GPL can be found at /usr/share/common-licenses/GPL. /usr/share/doc/med-bio/copyright
Just do your normal business (less
/usr/share/doc/med-bio/copyright) and if the necessary package is not
yet installed, auto-apt
will care for the installation and
proceeds with your command. While this is really cool this is not
really intended for production a machine.
The short conclusion here is: There are no sophisticated tools which might be helpful to handle meta packages in Custom Debian Distributions - just some hacks using the powerful tools inside Debian.
dselect
tasksel
Tasksel
is the Debian task installer and the first interface for
package selection which is presented to the user when installing a new
computer. The End-user section should contain an entry for each
Custom Debian Distribution. This is currently the case for Debian-Jr.
Debian Task Installer v1.43 - (c) 1999-2003 SPI and others ————— Select tasks to install ————— –– End-user –––– [X] Debian Jr. [ ] Desktop environment [ ] Games [ ] Linux Standard Base [ ] X window system [ ] Office environment –– Hardware Support –––– [ ] Dialup internet [ ] Laptop [ ] Broadband internet connection –– Servers –––– [ ] DNS server [ ] File server [ ] Mail server [ ] Usenet news server [ ] SQL database [ ] Print server [ ] Conventional Unix server <Finish> <Task Info> <Help>
Unfortunately there are some issues which prevent further Custom Debian
Distributions from being included in the tasksel
list because all
dependencies of this task have to be solved on the first installation CD. This
can not be accomplished for all Custom Debian Distributions and so a different
solution has to be found here (see #186085
). In principle
tasksel
is a good tool for easy installation of Custom Debian
Distributions.
aptitude
dselect
and has some useful
support for searching for and grouping of packages. While this is not bad it
was not intended for the purpose to handle Custom Debian Distributions and
there could be some better support to handle meta packages more clever.
Short conclusion: There are good chances to get meta packages handled nicely by the text based Debian package administration tools but currently this is not yet implemented.
Debian Woody does not yet contain a really nice graphical user interface for the Debian package management system. But the efforts to support users with an easy to use tool were increased and so there are some usable options now.
gnome-apt
synaptic
Synaptic
has a nice filter feature which makes it
a great tool here. Moreover synaptic
is currently the only user
interface which supports Debian Package
Tags
.
kpackage
Short conclusion: As well as the text based user interfaces these tools are quite usable but need enhancements to be regarded as powerful tools for Custom Debian Distributions.
Web search
http://packages.debian.org/cgi-bin/search_packages.pl?keywords=med-\|[amp
]\|subword=1
As a result you will get a list of all Debian-Med packages.
Package Tracking System
http://qa.debian.org/developer.php?login=synrg
http://qa.debian.org/developer.php?login=tille
http://qa.debian.org/developer.php?login=pere
The other way to use the Package Tracking System is to search for packages starting with a certain letter:
http://packages.qa.debian.org/j
http://packages.qa.debian.org/m
But the list you get by this method is much larger than you would wish for a good overview.
So the conclusion is - we just need better support here for Custom Debian Distributions.
list-junior.sh
junior-doc
contains a script
/usr/share/doc/junior-doc/examples/scripts/list-junior.sh
which
checks for the installed packages of a Custom Debian Distribution and builds a
simple web page describing these packages. (The BTS contains a patch to let
this script work also for other Custom Debian Distributions.)
Short conclusion: Some very basic things can be done with the web interfaces described above but techniques have to be developed to provide useful information about each Custom Debian Distribution.
Obviously there are no nifty tools as you might know them from Debian available
yet. The user interfaces for apt-get
have to be enhanced
drastically to make them easy enough to make them useful in the hands of an end
user. This might implicitly mean that we need some additional control fields
in dpkg
to implement reasonable functionality. The following
items are target of future development:
aptitude
, synaptic
, etc.
tasksel
section
Furthermore it is necessary to find a set of keywords for each Custom Debian Distribution and write a tool to search these keywords comfortable. The best way to accomplish this might be to make use of Debian Package Tags which is a quite promising technique.
Tools which grep the apt cache directly for meta packages have to be written or rather the available tools for this should be patched for this actual functionality.
As stated above specialists have only interest in a subset of the available software on the system they are using. In an ideal world this software would be the only one which is presented in the menu. This would allow the user to concentrate on his real world tasks instead of browsing funny menus.
To accomplish this a technique has to be implemented which allows to define a
set of users who get a task-specific menu while getting rid of the part of
software they are not interested in. Moreover this has to be implemented for
certain groups of users of one Custom Debian Distribution which are called
"roles". There are several techniques available to manage user
roles. Currently in the field of Custom Debian Distributions a UNIX group
based role system is implemented. This means, that a user who belongs to a
certain group of a Custom Debian Distribution is mentioned in the
/etc/group
file in the appropriate group and gets a special user
menu which is provided for exactly this group.
Strictly speaking it is not the best solution to conflate a configuration mechanism (which users see which menus) with access control (unix groups). It might be confusing and wastes the limited number of groups to which a user can belong. On the other hand this is a solution which works for the moment and has no real negative impact on the general use of the system. The benefit of using unix groups is that there is a defined set of tools provided to handle user groups. This makes life much easier and there is no practical limit of the number of groups which a user can belong for the existing Custom Debian Distributions at the time beeing.
For the long run this role system might even be enhanced to certain "levels" a user can have and here the UNIX groups approach will definitely fail and has to be replaced by other mechanisms. This will include the possibility to enable the user adjust his own level ("novice", "intermediate", "expert") while only the administrator is able to access the UNIX groups. On the other hand such kind of user level maintenance is not only a topic for Custom Debian Distributions but might be interesting for Debian in general.
Another point which speaks against using UNIX groups for role administration is the fact that local administrators are not in all cases competent enough to understand the UNIX role concept as a security feature and thus a real role concept including tools to maintain roles are needed in the future.
The handling of the user menus according to the groups is implemented in a flexible plugin system and other ways of handling groups (i.e. LDAP) should be easy to implement.
The Debian menu system cares for menu updates after each package installation.
To enable compliance with the role based menu approach it is necessary
to rebuild the user menu after each package installation or after adding new
users to the intended role. This can be done by using the
cdd-update-menus(8)
(see cdd-update-menus(8), Section
6.4.2.2) script from cdd-common
. It has to be said that using
cdd-update-menus
is not enough to change the menu of a user. To
accomplish this a call of the general update-menu
script for every
single user of a Custom Debian Distribution is necessary if this is not done by
the postinst
script of a meta package. This can easily been done
if the configuration file of a Custom Debian Distribution
/etc/cdd/<cdd>/<cdd>.conf
contains the line
UPDATEUSERMENU=yes
It is strongly suggested to use the package cdd-dev
to build meta
packages of a Custom Debian Distribution which will move all necessary files
right into place if there exists a menu
directory with the menu
entries as described in cdd-install-helper(1), Section
6.4.1.2. Note, that the users ${HOME}/.menu
directory remains
untouched.
debconf
Using cdd-install-helper(8)
(see cdd-install-helper(1), Section
6.4.1.2) it is very easy to build a cdd-common
package which contains debconf
scripts to configure system users
who should belong to the group of users of the Custom Debian Distribution
cdd. For example see the med-common
package.
~> dpkg-reconfigure med-common Configuring med-common ---------------------- Here is a list of all normal users of the system. Now you can select those users who should get a Debian-Med user menu. 1. auser (normal user A) 6. fmeduser (med user F) 2. bmeduser (med user B) 7. glexuser (lex user G) 3. cjruser (jr user C) 8. hmeduser (med user H) 4. djruser (jr user D) 9. iadmin (administrator I) 5. eadmin (administrator E) 10. juser (normal user J) (Enter the items you want to select, separated by spaces.) :-! Please specify the Debian-Med users! 2 8
This example shows the situation when you dpkg-reconfigure
med-common
if med user B and med user H were
defined as users of Debian-Med previously and med user F should be
added to the group of medical staff. (For sure it is more convenient to use
the more comfortable interfaces to debconf
but the used SGML DTD
does not yet support screen
shots
.)
Building a meta package is more or less equal for each meta package. This was
the reason to build a common source package cdd
which builds into
two binary packages
cdd-dev
cdd-common
cdd-dev
. It introduces a method to handle system users in
a group named according to the name of the Custom Debian Distribution. The
user menu approach is explained in detail in User roles,
Section 6.3.
The usage of the tools which are contained in these packages are described now in detail.
cdd-dev
If meta packages are builded using the tools inside the cdd-dev
package it can be ensured that the resulting meta packages will work nicely
with the same version of cdd-common
package. The goal is to keep
necessary changes for the source of the meta packages of a Custom Debian
Distribution as low as possible when the version of the cdd
source
package changes. Thus it is strongly recommended to use the tools described
below.
The usage of the tools in the cdd-dev
package might introduce a
versioned dependency in the <cdd>-common
package
from which all other meta packages of the CDD in question will
depend. This <cdd>-common
package instantiates
the CDD in the common registry for all CDDs in
/etc/cdd
.
The current Debian-Med packages provide a working example how to use the tools described below.
cdd-gen-control
- install menu and link to helper bin and
according manpage
cdd-gen-control
cdd-gen-control
parses the tasks
directory
for text files which have a similar syntax to debian/control
files. Each text file is used as template for a
cdd-
textfile_name meta package and has to
define the dependencies.
debian/control.stub
.
/etc/cdd/sources.list
is used
to verify which packages are available. You can specify one of
stable, testing or unstable as argument
or a complete path to a valid sources.list
file.
pere@hungry.com
, Andreas Tille
tille@debian.org
The interesting thing in this script is that it can be ensured that the resulting meta package can be installed in the target distribution. For instance it might be possible that for certain reasons a meta package should work together with the current Debian stable distribution. If the package is builded against a sources.list package which contains entries for stable and some newer packages are not yet available, these ones are not listed as dependencies but only as suggested packages. That way it is possible to provide meta packages for using a stable distribution using the same package source as for testing or unstable where new packages normally go.
cdd-install-helper
- install menu and link to helper bin and
according manpage
cdd-install-helper
debian/rules
file to install the user
menu files to
/etc/cdd/
<cdd>/menu/
<package>,
a link for the helper script of every <cdd>-* package and the
link to the manpage for this script.
menu
menu
exists in the building directory it checks for
files named like meta packages (without the <cdd>- name
prefix). These files should be valid menu files as they are provided for
Debian packages in debian/menu
. They will be copied to
debian/
<pkg>/etc/cdd/
<cdd>/menu/
<pkg>
where tools like cdd-update-menus(8)
will expect them.
A check will be performed whether there are text files named
docs/
<pkg_without_cdd-prefix>/
<dependency>.txt
where <dependency> is a package which is listed in the
dependencies of the meta-package. These text files should provide reasonable
information how to use this program in text form which can be viewed by a
pager
which is better than having no menu entry at all. A menu
entry will be created which call the pager
to this text file after
checking whether this package is really listed in the dependencies.
common
common/common
and has a size greater than 0
a <cdd>-common package is builded. The file
common/control
was just used to build the appropriate
debian/control
file using the cdd-gen-control(1)
tool.
docs
docs/
<pkg_without_cdd-prefix>/
will
be copied to the appropriate doc directory of the meta-package.
conf
common/conf
and has a size greater than 0
this is used as special configuration file
/etc/cdd/<cdd>/<cdd>.conf
which
can override variables from the general configuration file
/etc/cdd/cdd.conf
or add further variables. Because it is sourced
from shell it has to follow shell syntax.
debian-med
source package.
tille@debian.org
.
sources.list
files in /etc/cdd/
These files are used by cdd-gen-control(1)
to build valid
debian/control
files which contain only available packages in
their dependencies. This enables building meta packages for
stable, testing, unstable or even a
completely different distribution which has valid sources.list
entries. The file /etc/cdd/control.list
is used as default for
cdd-gen-control(1)
and usually is a symbolic link (see
ln(1)
) to sources.list.
distribution. It
might be changed using the -sdist option of
cdd-gen-control(1)
.
TODO: Either parse the available
/etc/apt/sources.list
or use a sane debconf
question
to use the "nearest" mirror.
/usr/share/cdd/templates
The directory /usr/share/cdd/templates
contains templates which
can be used to build a <cdd>-common
which uses
the tools which are contained in the cdd-common
package and are
useful to manage <cdd> user groups (see User roles, Section 6.3).
cdd-common
This package creates a common registry for all CDDs in /etc/cdd
.
Each CDD should put the files which are used into a subdirectory named like the
CDD of /etc/cdd
. The cdd-common
package installs a
common configuration file /etc/cdd/cdd.conf
which can be used to
influence the behaviour of the tools described below.
cdd-role
- add/remove roles in registered Custom Debian
Distribution
cdd-role
add|del CDD [Role]
tille@debian.org
, Cosimo Alfarano
kalfa@debian.org
.
cdd-update-menus
- add menu of meta package to all Custom Debian
Distribution users
cdd-update-menus
[--cdd CDD | --user user]
If it's called by a user, it addds and keeps updated menu entries for the user who runs it.
If it's called by root, it adds and keeps updated user's menu entries (see menu package for users' menus) for all users who belong to the group of the specified Custom Debian Distribution, or only for a specified user, depending on which parameted is passed to the script.
tille@debian.org
, Cosimo Alfarano
kalfa@debian.org
.
cdd-user
- add/remove user to Role of a registered Custom Debian
Distribution
cdd-user
add|del CDD user
[Role]
tille@debian.org
, Cosimo Alfarano
kalfa@debian.org
.
cdd.conf
- configuration for Custom Debian Distribution registry
cdd-common
and thus it has to follow shell syntax. The
variables which are set inside this configuration file can be overriden by
special CDD configration files
/etc/cdd/<>cdd>/<>cdd>.conf
for each single CDD.
cdd-role (8)
, cdd-update-menus (8)
, cdd-user
(8)
tille@debian.org
, Cosimo Alfarano
kalfa@debian.org
.
Custom Debian Distributions
28 July 2004tille@debian.org