source: npl/overig/slacktrack/OVERVIEW @ 1393bb5

##############################################################################
# Document: OVERVIEW
# Purpose : Provide an overview of the Slackware package system incorporating
#           the use of 'slacktrack'
#           Please note that this is *not* a guide to the use of slacktrack;
#           the man page and SlackBuild scripts in the 'examples' directory
#           aim to fulfill that requirement.
# Date....: 15-May-2009
# Author..: Stuart Winter <mozes@slackware.com>
# Homepage: http://www.slackware.com/~mozes
##############################################################################


CONTENTS:
---------
1.0 Preamble
2.0  Slackware packages
     2.0.1 Format of official Slackware packages
          2.0.1.1 Package names
          2.0.1.2 Version numbers
          2.0.1.3 Architectures
          2.0.1.4 Build numbers
  2.1  An overview of the creation of official Slackware packages
       2.1.1 'Clean' and 'dirty' builds
            2.1.1.1 Clean builds
            2.1.1.2 Dirty builds
       2.1.1 SlackBuild and .build scripts
            2.1.1.2  SlackBuild scripts
            2.1.1.3  .build scripts
  2.2  slacktrack in the scheme of things
       2.2.1  Using slacktrack with official .build scripts
       2.2.2  Writing your own .build scripts for slacktrack
            2.2.2.1 Making use of slacktrack's environment variables
3.0  slacktrack in operation
  3.1  How slacktrack finds which files have been installed
       3.1.1 installwatch's author
4.0  Example scripts
     4.0.1  non-slackware example build scripts
     4.0.2  slackware example wrapper build scripts
5.0  Known problems/features of slacktrack
6.0  New features
7.0  Licence
 

 
1.0 Preamble
    ---------

I used to work for a company that provided web hosting and shell accounts.
When I started there were a number of shell servers all running various 
releases of RedHat Linux, in various states of repair.  I managed to convince
the management to let me try Slackware on there instead because I have a much 
stronger understanding of how to maintain and build server using the 
Slackware distribution.  This trial went well and within a few months all 
servers were converted to Slackware version 8.1.

In order to ease the speed of installation (and to prevent against 
forgetting to install or configure something critical), I wrote a
set of post installation scripts that upgraded Slackware packages,
configured numerous config files and copied pre-compiled software
(such as courier IMAP) onto the new system.
For other software that I could not simply copy, I'd compile it on the
new server.

However, it soon became clear that due to security updates and so on,
it became incredibly time consuming (not to mention seriously boring)
to compile PHP, Apache and so on on every server.

At this point, I began to investigate how to create packages for Slackware.


2.0  Slackware packages
     ------------------

    The Slackware Linux distribution consists of a variety of 'packages'
    that make up the distribution.  

    Traditionally, all packages are in '.tgz' format (a gzipped tar archive).
    Starting with Slackware v13, new compression formats are supported which
    are represented by three additional file extensions:

     .tgz - Gzip
     .tbz - Bzip2
     .tlz - LZMA
     .txz - XZ
   
    In this document, we use the file extension '.t?z' to represent
    one of the above file formats.

    Once you have initially installed Slackware from the installer screen,
    you have the facilities to install, remove or upgrade new or existing
    packages using the package management tools: 

       installpkg <package.t?z>  - install 'package.t?z'

       upgradepkg <package.t?z>  - upgrade existing 'package' with the
                                   new version specified at the command line.

       removepkg  <package>      - remove specified package


    Whilst the Slackware package system is not especially feature rich,
    Slackware's user base (including me) like it because it is simple.
    If we want to write our own package utilities then we can easily do so
    by examining the existing package tools and querying and amending the
    package database (text files).

    2.0.1 Format of official Slackware packages
          -------------------------------------

          In Slackware 8.1 and up, each package file is named as follows:

          packagename-version-architecture-buildnumber.t?z

          2.0.1.1 Package names
                  -------------

                  The package name is either the name of the single program
                  or the name of a collection of utilities that fall under
                  a single umbrella.
                  For example:
                    autoconf-2.54-noarch-1.tgz

                  That is the name of the autoconf package I have on my
                  Slackware 8.1 box.
                  'autoconf' is the name of the the entire collection of 
                  binaries and associated documents that are extracted from
                  the autoconf source distribution archive.
 
                  However, if we consider another example:
                    tcpip-0.17-i386-15.tgz                  

                  There is no single piece of software called 'tcpip'.  
                  This package contains a number of associated utilities 
                  written by different authors but bundled into one single 
                  'package'.

          2.0.1.2 Version numbers
                  ---------------
          
                  If the package is the name of a particular piece of software
                  such as 'autoconf' from the example above, then the version
                  number represents the version number that its authors distribute.
                 
                  If the package is a 'bundle' such as 'tcpip' then the version 
                  number increases as and when you add a new piece of software to 
                  the package, or upgrade a particular piece of major software 
                  contained within the package.
                  For example, with 'tcpip' above, the 0.17 refers to the version of
                  Linux Netkit.  However, there are other programs included within 
                  the Slackware tcpip package that are not part of 'Linux netkit'.
              
          2.0.1.3 Architectures
                  -------------

                  The architecture is just that -- it tells you which architecture
                  the package is for.

                  The current values in use are:

                     ----- [ Official Slackware architecures ]

                     noarch  - Architecture independent files such as config files 
                     i386    - packages for the x86 (Slackware v8.1 & 9)
                     i486    - packages for the x86 (Slackware 9.1+)
                     i586    - packages for the x86 
                     s390    - packages for the IBM s/390 mainframe

                     Note: Whilst Slackware v10 is primarily built for i486, you may
                           find that there are some packages whose architecture versions
                           are higher than i486. This is for two reasons:

                           [a] There is no source for the package - it is a repackaged
                               binary distribution (SUN's j2sdk is an example).

                           [b] The package is not required or otherwise not suitable for
                               earlier revisions of the architecture (this is especially
                               the true with ARM and SPARC).                                

                     ----- [ Unofficial ports of Slackware ]

                     arm     - packages for the ARM architecture
                     sparc   - packages for the SUN Sparc architecture
                     powerpc - packages for the PowerPC architecture
 
          2.0.1.4 Build numbers
                  -------------

                  A build number suplements the version number and is changed
                  when the *package maintainer* makes a change to the package but
                  the original source code and version number remains the same.

                  For example, I build a package of 'foo' version 0.14 for the
                  sparc.  I have never built this package before, thus it becomes
                     foo-0.14-sparc-1.tgz
                  However, I realise that I haven't configured 
                  the 'bar' parameter correctly in /etc/foo.conf.  I fix it 
                  and re-build the package.  The package is now named
                     foo-0.14-sparc-2.tgz            


  2.1  An overview of the creation of official Slackware packages
       -----------------------------------------------------------

       This section gives a brief introduction of the two methods of
       used when building the official Slackware packages.
      

      2.1.1 'Clean' and 'dirty' builds
            --------------------------
                 
            I am assuming the reader has some experience with Makefiles
            and has compiled and installed a number of software packages.
             
            2.1.1.1 Clean builds
                    ------------

            I term a 'clean' package one where you can specify a variable
            to the 'make install' which contains the directory you wish to install
            the package in, rather than installing it properly over the root file system.
            For example: 
            # ./configure --prefix=/usr --sysconfdir=/etc
            # make
            # make install DESTDIR=/tmp/package-foo

            With a 'Makefile' that honours the DESTDIR variable, this will
            install the whole package into /tmp/package-foo.  This directory
            effectively is the 'root' directory '/' as far as the Makefile
            is concerned.

            From here you can use the Slackware 'makepkg' program and build
            a package.

            This is by far the safest and most preferred method by all
            users that make packages.

            You will find that DESTDIR is called prefix, TOPDIR and other names;
            you need to examine the Makefile scripts in order to determine whether
            it contains this functionality and if it does, then discover what 
            the variable name is.

            2.1.1.2 Dirty builds
                    ------------
            
            A 'dirty' build is the name I give to source distribution archives
            whose Makefile scripts do not have any provisioning to install
            in an alternate directory other than root.

            For these type of builds, you will typically do:
            # ./configure --prefix=/usr --sysconfdir=/etc
            # make
            # make install

            The package will then be installed on the root filesystem.
            
            So how do you know what files were installed where and
            even if you did, how do you pull all these files together in order
            to run makepkg over them ?
            That's the purpose of slacktrack! :-)


      2.1.1 SlackBuild and .build scripts
            -----------------------------
            
            Slackware has a number of packages by a great number of authors.
            Some of the packages's source Makefiles honour a DESTDIR type
            variable but others do not.
             
            2.1.1.2  SlackBuild scripts
                     ------------------

                     SlackBuild scripts can be 'interesting'.  They are 
                     scripts that install into a 'clean' environment (usually /tmp).  

                     Some of the scripts follow the make install DESTDIR=
                     style, if the Makefile permits.

                     Others have a 'framework' or 'controller tarball' which is
                     a _packagename.t?z (note the prefixing underscore).

                     The SlackBuild script uses the Slackware 'explodepkg' script
                     to untar the contents of the _.t?z into the /tmp-package<name> 
                     directory.
                     Slackbuild then runs 'make' to compile the binaries
                     and libraries, but then uses the 'cat' program such as:
                     # cat foobar > /tmp/package-foobar/usr/bin/foobar
            
                     By using 'cat', the *new* version of 'foobar' retains
                     the original permissions and ownerships that are in the 
                     controller tar ball.

                     However, you may be wondering how, if the package does not
                     have a facility to install into somewhere other than root, 
                     do we get the file names and permissions for the 
                     controller _.t?z in the first place.
                     The answer is simple:
                       [a] find all files on the file system and dump to a file.
                       [b] compile and install the software
                       [c] find all files on the file system and compare the file
                           produced by the first 'find'.  After a little pruning, you
                           have the list of files for the controller tar ball.


             2.1.1.3  .build scripts
                      ---------------

                      For those software distributions whose Makefile does not hounour
                      the DESTDIR type system, there are Slackware's .build scripts.

                      These scripts literally ./configure ; make ; make install
                      and copy docs and other goodies into the root file system.

                      One of the problems with these scripts is that they are 
                      often incomplete -- they build and install the package but 
                      do not gzip the man pages or strip the binaries and libraries;
                      this is done manually afterwards.

                      *These* are the scripts that slacktrack and altertrack were 
                      written for.

                   *  Note: Whilst some software's Makefiles may appear to honour
                      the DESTDIR variable, the Makefile *may* be broken which can
                      result in files missing or corrupt within your new package.
                      For example: I built Apache v2.0.48 and built a package using
                      make install DESTDIR.  However, a problem exists in that some of
                      the Perl scripts it installs have *temporary build paths* 
                      hard coded into the resulting scripts.
                      This is why you *may* find a .build instead of a SlackBuild
                      script within Slackware's source tree.

                      However, the primary reason is because the build script just
                      hasn't been updated to make use of DESTDIR.                    *
                       

  2.2  slacktrack in the scheme of things
       ----------------------------------

       I follow Slackware-current quite closly.  Often I want to 
       'back port' a -current package to an earlier release of Slackware .
       I can't simply upgrade with -current's package because it was 
       compiled for a newer GLIBC than Slackware 8.1's, for example.
       For packages that use a 'clean' 'SlackBuild' script, this is
       an easy job -- I simply run 'SlackBuild' on an 8.1 box.

       However, for .build scripts, I needed a way of building packages
       using Slackware's .build scripts.

       I found a great program called 'CheckInstall' which fulfilled most of my
       requirements.  However, as time went on and I started building
       more of Slackware's packages and writing my own build scripts, I found
       that checkinstall was lacking some features that I required.
       At this time I was also considering porting Slackware to run on
       the ARM architecture and helping with the Splack (Slackware on SPARC project),
       and therefore wanted a robust program that can deal with every .build script
       I threw at it, and if it can't handle it, I needed to be able to make modifications. 
       The easiest  way of doing this was to write my own script; thus 
       'slacktrack' was born.

       slacktrack is based on the *idea* behind 'CheckInstall', but uses
       only my own code (and contributions from other users), and only contains 
       Slackware-specific facilities -- it can not build Debian or RedHat packages
       and never will.

       slacktrack does not have all of the facilities of CheckInstall either,
       but then these are not required for building Slackware packages
       from .build scripts.

       Also, slacktrack only works with 'official' Slackware directory locations
       and /usr/local.
       For example, if your make install installs binaries in /opt/packagename/bin
       and the man pages in anywhere other than /usr/man or /usr/local/man, then 
       slacktrack's relevant options (eg stripping libs, bins, gzman) will 
       not detect them.
      
   
      2.2.1  Using slacktrack with official .build scripts
             ---------------------------------------------              

             Building a replicar Slackware package from a .build script is
             typically fairly trivial with slacktrack.

             If we wanted to build slackware-9.1's elvis, we could do
             # cd slackware/slackware-9.1/source/a/elvis
             # chmod 755 elvis.build
             # slacktrack -jefkzp "elvis-2.1-i386-2.tgz" ./elvis.build
             
             The resulting package (by default) be stored in 
             /tmp/built-slackwarepackages/

             As already mentioned, some of the Slackware .build scripts
             are incomplete with regard to gzipping man pages, stripping binaries
             and so on -- fetchmail.build is one of them.
             Therefore you can specify various options to slacktrack that
             will take care of this for you.
             The options in the example above :
                 j - compress libraries
                 e - chown root:bin /bin,/sbin,/usr/bin,/usr/sbin directories
                 f - chown root:bin files in the binary dirs listed above
                 k - strip binaries found in the binary dirs listed above
                 z - gzip man pages
                 p - the resulting Slackware package .t?z name

             The way I re-create the packages is to build a 'trackbuild' script that
             launches slacktrack with the required options and the name
             of the Slackware .build script.  You can find examples of such
             scripts within the docs directory after installing slacktrack:

                /usr/doc/slacktrack*/buildscript-examples/

             You will also find that in Slackware versions 12.0 and upwards,
             the .build scripts are accompanied by 'trackbuild' scripts because
             slacktrack is used by the Slackware team to produce the packages.
 
      2.2.2  Writing your own .build scripts for slacktrack
             ----------------------------------------------
             
             There isn't any specific that you have to do to write a build
             script for use with slacktrack -- the script name specified to
             slacktrack doesn't even have to be a script - it can be a binary -
             as long as it is executable, it is acceptable.

             You can see some of my own build scripts that I have written
             for use with slacktrack by looking in the documents directory
             after installing slacktrack:

                /usr/doc/slacktrack*/buildscript-examples/

             2.2.2.1 Making use of slacktrack's environment variables
                     -------------------------------------------------
                  
                     slacktrack exports two environment variables:
                     SLACKTRACKFAKEROOT and SLACKTRACKSCRATCHDIR

                     SLACKTRACKFAKEROOT:
                     ````````````````````

                     The purpose of this to allow your .build script to access the
                     'root' directory of the resulting package.
                     There are two scenarios where you may want to use this
                     variable:

                     1.  During the build:

                     The reason you may wish to do this is to pre-populate 
                     the package with files that you may not wish to place directly
                     onto the root filesystem.
                     The package contents will only appear inside this directory
                     once your build script has finished, and slacktrack has determined
                     what to put into this directory.

                     In previous slacktrack versions which used a pseudo-root filesystem
                     (where the package contents were populated *during* the build), this
                     made sense, but in slacktrack v2.00, it is unlikely that you'd want
                     to use this vairable from the build script.

                     2.  Post-build -- cleanups after the build:
                     
                     The most likely use of this script is to perform package cleanup
                     tasks after the build.  This is mainly to perform tasks that slacktrack
                     does not handle itself - such as deleting known files/directories that
                     creep into packages (due to a system daemon such as CUPS), or setting
                     some file and directory permissions.

                     An example post build script is below.
                     A post build script can be specified by slacktrack's -R option:

   # Incase you had CUPS running:
   rm -rf etc/cups etc/printcap
   # crond:
   rm -rf var/spool/cron
   rmdir var/spool

   # perllocal.pod files don't belong in packages.
   # SGMLSPL creates this:
   find . -name perllocal.pod -print0 | xargs -0 rm -f

   # Some doc dirs have attracted setuid.
   # We don't need setuid for anything in this package:
   chmod -R a-s .


                     SLACKTRACKSCRATCHDIR:
                     `````````````````````

                     The purpose of this variable is to provide some temporary
                     space to untar your source archives and so on.  slacktrack
                     will manage the creation and deletion of this directory.

                     For example:
                     # cd ${SLACKTRACKSCRATCHDIR}
                     # tar zxvvf ${ORIGPATH}/source/foobar.tar.gz
                     
                     You can see in some of the example 'non-slackware' scripts
                     how I have used these variables
                     

3.0  slacktrack in operation
     -----------------------
     
     The basic event flow is as follows:

     [1] Parse command line arguments
         -> Check they are OK, if not bomb out 
     [2] Launch the supplied build script
     [3] Run any specified functions (eg gzman, strip bins, chowns) over the
         package 'root' directory and contents
     [4] Run Slackware's 'makepkg' program over the package contents
     [5] Move the .t?z to the specified build store path
     [6] Scan for any hard links that may be in the package
         -> If any found, alert the user on screen and also
            log to a packagename.hardlinks.log file in the build store path

     The slacktrack shell script is fairly simple and well commented; it should be
     relatively easy for anybody who understands bash to quickly comprehend what 
     is happening and why.

    3.1  How slacktrack finds which files have been installed
         ----------------------------------------------------
         
         In order to track the files and directories that have been installed
         or changed, slacktrack follows this ordered process:

         [1] Scans a pre-set list of directories on the filesystem and
             logs the contents.
         [2] Launches build script which installs the package onto the
             filesystem
         [3] Scans the filesystem once again
         [4] Compares the differences in the before and after snapshots
         [5] Copies the differences into a 'package root directory' and
             runs makepkg over them.

         In slacktrack version 1, we used 'installwatch' which overloaded
         some of glibc's filesystem calls, creating new files and directories
         into a pseudo-root filesystem, avoiding the need to install onto
         the host's filesystem (and also allowing to build as a non-root user).
         However, this library is ill maintained and even in the early days
         when it worked well, it still had problems and workarounds were required.
         
4.0  Example scripts
     ---------------

     Included with the slacktrack binary distribution are a number of example
     scripts that hopefully should provide you with a basis of how to use slacktrack
     to build from 'dirty' source distributions.
     
     The examples are bundled in the documentation directory available 
     after installing slacktrack:

               /usr/doc/slacktrack*/buildscript-examples/


5.0 Known problems/features of slacktrack
    -------------------------------------
 
     Current problems:

       [1] slacktrack doesn't have sufficient error checking.  

            I'm in two minds about *where* to put error checking, you see.
            Do I go no further if the supplied build script exits with a non-zero
            value?  
            No, that's a bad idea because what if you didn't write the build script?
            it might be one of these qmail type binary installer programs that
            you can't (easily without hacking the source) fix.  The author may
            have their own systems, and the program exits with a value that their
            own controller script recognises as non-failure.
   
            What should I do if makepkg has failed?  You see it on screen
            and in the logs anyway, plus makepkg is one of the last things
            that slacktrack calls -- how can you recover?
       
            That said, version 1.03 now has some error handling.  There's still
            not enough though, imo.

        [2] No support for a default config file

            I don't see the point.  Each .build script is different
            and although I typically use the same options to slacktrack
            for most of my build scripts, I don't see why I'd need a 
            config file just to save 4 bytes or so in a trackbuild wrapper :-)

        
6.0  New features
      -------------

      See the TODO file in the docs directory.

      If you have any specific features you would like to see
      included, or have found any bugs, please 
      email me <mozes@slackware.com>

7.0  Licence
     -------
   
     slacktrack is distributed under BSD Licence.