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оригинального документа
: http://www.adass.org/adass/proceedings/adass02/P8-2/
Дата изменения: Thu Mar 13 03:24:20 2003 Дата индексирования: Tue Oct 2 04:41:26 2012 Кодировка: Поисковые слова: merging galaxies |
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The rise of the Open Source movement has brought standard tools into common use to cope with such large and complex tasks. The RedHat Package Manager (RPM) software is one such which is available for many platforms. We have shown it is possible to automate the distribution and installation of the Starlink Software using RPM. We anticipate that this will vastly simplify installation and package management for Systems Administrators who must support the USSC in production data processing environments.
The Starlink Software Collection (Bly et al. 2003) is a large collection of software packages comprising subroutine libraries, applications packages and utilities for astronomical data reduction and analysis. The whole collection is governed by a set of interdependencies which not only complicates the process of building the software but also which packages depend on which others at runtime.
Each package has its own makefile which contains the rules defining how and in what order the components should be built, and their dependencies on other packages. However, none of the packages are able to trigger the building of another package -- this is traditionally done by a master makefile which builds the packages in the correct order.
The master makefile is maintained by the Software Manager but has two disadvantages -- it does not express the package dependencies at run-time, and contains only a simple ordered-list of packages to build -- making it difficult to slot a new package into a suitable place in the build sequence. A new approach to managing the build and installation dependencies was needed. We have investigated `wrapping' the USSC using the RedHat Package Manager (RPM) system (Bailey, 1997) and have shown it is possible to automate the building and distribution and simplify the installation and maintenance of the USSC for Systems Administrators and users.
The RedHat Package Manager is becoming ubiquitous in the Linux world, having been adopted by most of the major distributions. It is also supported on may other Unix systems including those supported by Starlink. The RPM system has several advantageous features:
Each Starlink package has its own makefile and documents which conform to a standard template, although the makefile and documents may have slight variations from the standard. This makes them suitable for processing to provide RPM with the information it requires.
RPM requires a `spec' file for a package, to define the various dependencies. These can be generated by hand or automatically by processing a master dependency list. A template dependency file depend.ini was created by hand listing the software group, version, and list of SUNs (Starlink User Notes -- the documents) and then a Perl script is used to extract summary and abstract information from the package documents. The buildrequires and fixup lines are then added by hand examination of the makefile to see which files are edited and in what way at installation time. Buildrequires expresses the additional packages required at build time and fixup expresses files that have to be changed at installation.
A dependency file may contain details of more than one package -- the abstract extraction script getabst.pl processes all the package entries. Where the document listed in the depend.ini file does not have the appropriate LATEX keywords, the keys are left blank. Since this is demonstrating the concept, the system depends on an existing Starlink installation with source files from which it extracts its data.
Once a dependency file is ready, the RPM `spec' file(s) can be generated. This is the file that controls what RPM does when building and manipulating the package. A Perl script mkspec.pl has been produced to interpret the dependency file and generate `spec' files based on a template for all packages listed in the dependency file.
Existing Starlink installations do not have the source packaged in a single tarball though the makefiles can provide them via the export_source target which generates a compressed tarball of the appropriate files. The master makefile can generate tarballs for all the packages.
The next step is to create a set of links for each package from an existing USSC installation to the standard location for RPM build directories. A Perl script mklinks.pl does this for all the packages in the dependency file, creating links from /usr/src/redhat/SOURCES to the source files. Since the default location is /usr, one has to be root for this and the remaining steps. Once the links are in place, the `spec' files are copied to the /usr/src/redhat/SPECS directory and the rpm program can take over to build the RPMs, both source and installation sets.
The resulting RPM files are re-locatable so you don't have to install the packages in the default location ( /star). Using the -relocate command line switch one can instead direct the package to any chosen path -- since the normal location is /star, one has to be careful where there is an existing (non-RPM) USSC installation. Most packages are easily re-locatable and do not require special tricks to be detailed in the depend.ini file. However, some packages do have complex installation requirements and these need to be carefully expressed. The whole collection can be processed to build RPM sets and installations made based on them.
This work is proof of concept. The technology for extracting dependencies and details from the existing build systems is rather basic, and some Starlink packages are under regular development which tends to change the dependencies. Stable packages such as libraries are easier to deal with. Nevertheless we have demonstrated that RPM can be adapted to deal with an alien software management system.
Bailey, E. 1997, ``Maximum RPM'', Sams, ISBN: 0672311054
Bly, M. J., Giaretta, D. L., Taylor, M. B., & Currie, M. J. 2003, this volume, 445