Alpine package format

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(Last edited by Aalatchm on 29 Jun 2012.)

From apk-tools-2.0_pre15 there is support for signing of packages and indexes. This introduced a new format for both packages and indexes. This document describes the new format.

The new apk package are 2 combined tar.gz packages, control.tar.gz and data.tar.gz. The final .apk package is created by concatenating control.tar.gz and data.tar.gz.

For example:

cat $controldir/control.tar.gz $controldir/data.tar.gz > mypackage-1.0-r0.apk

control.tar.gz

The control package contains

  • .PKGINFO
  • .pre-install/upgrade/deinstall (optional)
  • .post-install/upgrade/deinstall (optional)

Since the data.tar.gz will follow the after the control.tar.gz, the end-of-tar record in the tar archive must be removed. This is done by filtering the tar package through abuild-tar --cut:

tar -c .PKGNIFO .pre-install | abuild-tar --cut | gzip -9 > $controldir/control.tar.gz

.PKGINFO

the .PKGINFO is very similar to archlinux's .PKGINFO.

Format is key[space]=[space]value.

key = value

The following keys are supported:

  • pkgname - the name of package
  • pkgver - the version, including the pkgrel.
  • depends (each dependency has its own line)
  • datahash

.*-install/upgrade/deinstall

The .pre-install, .pre-upgrade, .pre-deinstall scripts are executed before respectively, install, upgrade or uninstallation of a package. Apk will halt current action if script exits with error.

The .post-* scripts are executed after respecitvely install, upgade or uninstall of a package.

data.tar.gz

The data is a tar package with checksums embedded in the tar headers. The tar headers with checksuma are created by filtering the tar archive via the abuild-tar utility.

The data.tar.gz can be created with:

cd $pkgdir
tar -c * | abuild-tar --hash | gzip -9 > $controldir/data.tar.gz

The reason for creating data.tar.gz separately is because a hash will be created and stored in .PKGINFO for future package signing.