Software Packaging with RPM

Transcription

1 Software Packaging with RPM Andrew Ford 18 April 2013 Copyright 2013 Ford & Mason Ltd

2 About this talk Covers package building not package management Material was collected for a book: The RPM Handbook Warning: this talk is not exhaustive!

3 Outline of talk What is RPM? Building RPMs Dependencies and capabilities Macros Running rpmbuild Anatomy of a specfile Build scripts Management scripts and triggers Evolution of RPM Sources of further information

4 What is the significance of packaging? Ian Murdoch, founder of Debian, suggested in 2007 that: [Package management is] the biggest advancement Linux has brought to the industry Debian and RPM packages evolved at roughly the same time and are comparable in functionality

5 Why is RPM relevant? Provides a straightforward, consistent way to manage software and resources directly or through higher-level tools The fundamental building block of distros Widespread use: RPM-based distros (RHEL, Fedora, SLE, opensuse) Independent Software Vendors (ISVs) Packages for internal use Well-constructed packages give a professional impression

6 RPM design goals Upgradability (easy to install, upgrade and remove packages) Powerful querying System verification Pristine sources (start with original, upstream source code) Reproducible builds

7 Issues with RPM Poorly documented Shows signs of age but it is evolving Enterprise distributions lag behind latest developments (newer features often not available for several years) Many packaging details are distribution-specific (see Fedora, opensuse and Mandriva packaging guidelines) Information and misinformation on the internet

8 Versions of RPM in use Version Date Used by (EOL) SUSE RHEL 5 (2017/2020), SUSE RHEL 6 (2020/2023) OpenSUSE 12.2 (2014) Fedora 17 (2013) Fedora 18 (2014) These are just the versions still in use by major distributions. Prior to 2005 RPM development languished. Version is the first version of the relaunched rpm.org In 2006 RPM was forked by the previous developer rpm5 is only used by Mandriva

9 What does RPM consist of? Package file format (.rpm and.srpm) contains metadata and payload Package database (/var/lib/rpm/*) information on installed packages Configuration files (/etc/rpm/* and /usr/lib/rpm/*) Run-time admin tools (rpm command) Build tools (rpmbuild command) Libraries used by tools such as yum and the rpm tools themselves

10 What does RPM do? Installs, erases and updates packages Reports on what packages are installed Verifies installed packages Checks dependencies within sets of packages being installed, upgraded or removed Underpins higher-level packaging tools e.g. YUM, PackageKit, Zypper (these resolve dependencies, as well as checking) Provides a package build tool (rpmbuild)

11 Building RPM packages Dependencies Macros The build environment The build process Scriptlets, Scripts, and Triggers

12 Dependencies Dependency tracking is fundamental to packaging systems Ensures that software being installed has all its prerequisites Ensures that packages aren't inadvertently removed while other packages depend on them Differentiate between dependency checking and dependency solving

13 Dependencies (2) Packages provide capabilities (text strings) One automatic capability is the name of the package Special capabilities: rpmlib(feature) interp(module) e.g. perl(class::accessor) Requirements can specify versions of capability: op [epoch:]version[-release]

14 Version comparison rules Epoch - integer comparison Version and release: Split into numeric and alpha substrings and compared substring by substring (separators ignored) Leading zeroes ignored Longer substring or sequence is newer e.g.: > 1.9 1a > 1B 3:1.0 > 2: abc = 1_2_3_abc

15 RPM macros Macro values control all rpm tools (rpmbuild, rpm, etc) e.g.: %_topdir defines build directory (~/rpmbuild) %_binary_payload defines payload format and compression Defaults defined in /usr/lib/rpm/macros About 250 macros another 80 commented out

16 RPM macros (2) Can be defined: In macro files (/usr/lib/rpm/macros, /etc/rpm/*, ~/.rpmmacros) On the command line for all commands (-D 'name definition') In spec files %global name[(args)] expansion %define name[(args)] expansion By rpmbuild internally e.g. Name tag causes %name macro to be defined with the tag's value Note: parameterized macros definitions are evaluated twice (on definition and use), simple macros are evaluated once (on definition)

17 RPM macros (3) Usage %name or %{name} note: if the macro is not defined you get literal string in output Conditionals: %{?name[:expansion]} %{!name:expansion} %if expr... %else... %endif %ifarch / %ifnarch / %ifos / %ifnos Shell escape: %(command arg...) Messages: %{echo: msg} (also warn and error) Dump all definitions: %dump

18 Building RPMs Packages are normally built from sources and patches Aimed at software that follows GNU Coding Standard (autoconf/automake, etc) works best if you don't fight it RPM packages built with rpmbuild command (-ba option to build everything) Controlled by spec file (which may be located within tar file use -ta) Spec file can define multiple packages Spec file specifies build requirements (can be installed with yum-builddep from yum-utils)

19 Build process rpmbuild initializes itself from macro files (/etc/rpm/*, /usr/lib/rpm/macros, ~/.rpmmacros) Reads spec file, expanding macros as it goes Steps through build stages specified by spec file Determines dependencies and capabilities provided Constructs binary RPM and/or source SRPM Note: never build as root! always test RPMs on a clean system or with mock to identify unspecified dependencies (which may be satisified by s/w installed on the build system)

20 Build environment Build area is a directory hierarchy location specified by %_topdir (~/rpmbuild) SPECS/ (% specdir) SOURCES/ (% sourcedir) BUILD/ (% builddir) BUILDROOT/ (% buildroot) RPMS/ (% rpmdir) SRPMS/ (% srcrpmdir) Setup directories under $HOME with rpmdev-setuptree (from rpmdevtools package)

21 Spec files Complete specification of package Defines meta data for package (name, version, release, license, etc) Specifies dependency information Describes software build process Provides a manifest of the files to be installed Provides scripts for package install/erase Note: clumsy syntax %thing may be a macro, a spec file section or an file attribute depending on context Comments are marked with #, but macros within comments are expanded which can cause problems

22 Spec file sections Preamble (subpackage preambles introduced by %package) Package description (%description) Build script sections (%prep, %build, %install, %check, %clean) Run-time scripts (%pre, %post, %preun, %postun, %pretrans, %posttrans, %verify) Trigger scripts (%triggerprein, %triggerin, %triggerun, %triggerpostun) Files manifest (%files) Change log (%changelog) Subpackages have separate description, run-time scripts, triggers and manifests (sections qualified with subpackage suffix or full name)

23 ~/rpmbuild/ (%_topdir) Name: pkg Version: 1.0 Release: 1 SPECS/ %prep %setup -q %build configure make SOURCES/ BUILD/ %install make install %files BUILDROOT/ pkg.spec RPMS/

24 Example spec file Name: hello Version: 2.7 Release: 1%{?dist} Summary: GNU 'hello world' program Group: Miscellany Vendor: Free Software Foundation License: GPLv3 URL: BuildRoot: %{_tmppath}/%{name}-root-%(%{ id_u} -n) Requires: info Source0: %{name}-%version.tar.gz %description GNU Hello produces a familiar, friendly greeting. The practical purpose Of GNU Hello is to serve as a minimal example of a GNU package. %prep %setup -q %build %configure make %install make install DESTDIR=$RPM_BUILD_ROOT

25 ExamplesSpec file (continued) %clean rm -rf $RPM_BUILD_ROOT %post /sbin/install-info %{_infodir}/hello.info.gz %{_infodir}/dir : %preun if [ $1 = 0 ]; then /sbin/install-info --delete %{_infodir}/hello.info.gz %{_infodir}/dir : fi %files %defattr(-,root,root,-) %doc README /usr/bin/hello %exclude /usr/share/info/dir %doc /usr/share/info/hello.info.gz /usr/share/locale/*/lc_messages/hello.mo %doc /usr/share/man/man1/hello.1.gz %changelog * Fri Apr <andrew@ford-mason.co.uk> Initial packaging

26 Spec file preamble Consists of key-value records before first section Name: name of the software package Version: version number of the upstream source code Release: number of this release of the software package Summary: short, one-line description of the package URL: web site URL for software License: licence for the software Group: category the software falls in Source0: file containing the N'th source file Preamble for subpackages specified with %package section Info corresponds to output from rpm --query info %description section provides more detailed description

27 Specifying dependencies Automatic and manual dependencies (scripts % find_requires and % find_provides) Packages provide capabilities (including one with the name of the package) Specify capabilities provided with Provides tag Required packages/capabilities with Requires tag PreReqs tag is deprecated use Requires(pre) Conflicts specified with Conflicts tag SUSE has soft dependencies (Suggests and Recommends) these may come to later versions of rpm

28 Specifying dependencies (2) Dependencies and capabilities provided can be Automatically determined by rpmbuild (and helpers) Manually specified (%requires, %provides, etc) Automatic dependency generators run by rpmbuild after %install section Also need to specify build dependencies

29 Build process in detail %prep Unpacks source files and applies patches, e.g.: %prep %setup -q %patch0 Process often acheived with two pseudo -macros: %setup unpacks (compressed) tar files into build dir %patchn applies patch N

30 Build drocess in detail %build Configures and builds software e.g.: %build %configure make %configure runs GNU configure make is standard Linux make command

31 Build process in detail %install Installs to the build root - a staging area (proxy for the real root directory) %install make install DESTDIR=$RPM_BUILD_ROOT Installs into build root (proxy for the filesystem root) Configure-generated makefiles support $DESTDIR

32 Debugging RPM build scripts rpmbuild creates temporary script files Build can be executed up to a certain stage -bp stop after %prep -bc stop after %build (compile stage -bi stop after %install -bl do list check (expand %files and check everything exists) --short-circuit option to skip to stage specified with -bc, -bi or -bb (but makes generated RPM essentially unusable) shortrpm program can be used to create installable RPMs skipping prep and build stages but should only be used in development Alternatively exit 1 to build or install script, and examine and debug the script left in /var/tmp

33 Management scripts Scripts run before/after package installation, upgrade and erasure %pretrans run at start of transaction %pre before package installed %post after package installs %preun before package uninstalled %postun after package uninstalled %posttrans at end of transaction %verifyscript run by rpm -V On upgrade install scripts are run from new version of package, then uninstall scripts from old version Install scripts are not interactive we're not on Debian here!

34 Management scripts (2) Uses: Set up users and groups Install services and cron jobs, set up alternatives Refresh dynamic linker bindings (ldconfig) Scripts receive argument $1 says how many instances left at end of operation: 1 after first install 2 for install of new version on upgrade 1 for uninstall of previous version on upgrade 0 for final uninstall

35 Management scripts (3) Scripts can be provided for subpackages (specify name after script tag) Interpreter specified with -p program Default interpreter is /bin/sh <lua> for built-in lua interpreter (all that is available on %pretrans of first-stage install) Can specify /sbin/ldconfig if that is all that needs to run Creates an automatic dependency on interpreter

36 Triggers Scripts that run when a target package is installed or uninstalled: %triggerin run when target or source package installed/upgraded %triggerun run when target or source package is uninstalled %triggerpostun run after target package is uninstalled e.g.: %triggerin -p /bin/sh postfix Trigger scripts invoked with two arguments: $1 gives number of instances of source package remaining when trigger completes $2 gives number of instances of target package remaining

37 File lists List of files in package(s) specified by %files List can be read from file with -f file Attributes specified with %defattr, %attr Configuration files marked with %config Documentation flagged with %doc (collected and placed in /var/share/doc) 4.11 introduces %license to mark license files Error if there are unpackaged files in build root

38 Repeatable builds BuildRequires specifies packages needed for building Building under mock can ensure unspecified dependencies are identified basic usage: mock -init chroot-name mock -root chroot-name \ -rebuild package.src.rpm Should also test installation of built packages

39 RPM evolves Just a couple of examples (remember RHEL5 uses ): BuildRoot tag now silently ignored Group tag no longer mandatory %_topdir now $HOME/rpmbuild (was /usr/src/redhat) New macros %patches and %sources Support for XZ compression Group tag in subpackage inherits from main package New macros %getenv and %getconfdir

40 More changes (used by RHEL6) Deprecated Copyright tag no longer recognized PreReq and BuildPreReq are deprecated New BugUrl tag and %_bugurl macro New %make_install macro Macros %PACKAGE_VERSION and %PACKAGE_RELEASE removed (use %version and %release) New Requires(pretrans) and Requires(posttrans) tags New OrderWithRequires tag --sign option to rpmbuild no longer supported (now is a separate command rpmsign) Release notes on rpm.org have the details

41 And there's more... Multilib SE Linux policies POSIX capabilities Software collections

42 Sources of further information Man pages for rpm, rpmbuild, etc rpm.org fedoraproject.org/wiki/ Category:Package_Maintainers opensuse.org/portal:packaging wiki.linuxfoundation.org/en/lsb (Linux Standards Base) Classic Shell Scripting, Robbins & Beebe (O'Reilly) AUTOTOOLS, John Calcote (No Starch Press) GNU Coding Standards (Free Software Foundation) rpmhandbook.com (coming soon)

43 Thank you