Ian Wienand 4dbfab66a1 Pre-install python3 for CentOS
CentOS 7 is the only distro we support currently that doesn't have
Python 3 installed in some form in the base images.  For centos 7 add
an early install of it in the yum element so we can have all the
in-chroot scripts assume Python 3.  There is only one package that
causes issues; yaml which comes from EPEL.  Everywhere else it is a
base package, but we don't have a way to say "enable epel to install
this".  Just hack it in, we don't want to go reworking the world for
CentOS 7 at this point.

Also add python3 and it's yaml library to the centos 8 path.  This
brings in the "user" python3 in /urs/bin/python3 (the "system" python3
is already installed).  Again, this just lets us assume
/usr/bin/python3 in scripts for all platforms.

package-installs is one of these things running python in the chroot,
and unfortunately we have elements that use it at 01- level in
pre-installd.  Thus to make sure python3 is there nice and early, run
it at 0 level, but make sure it comes after yum/dnf update.

Change-Id: I088fc4284e889147ca9a375d4a159264cff53484
2020-08-07 10:34:03 +10:00
..
2020-07-07 12:53:51 -07:00

package-installs

The package-installs element allows for a declarative method of installing and uninstalling packages for an image build. This is done by creating a package-installs.yaml or package-installs.json file in the element directory.

In order to work on Gentoo hosts you will need to manually install dev-python/pyyaml.

example package-installs.yaml

libxml2:
grub2:
  phase: pre-install.d
networkmanager:
  uninstall: True
os-collect-config:
  installtype: source
linux-image-amd64:
  arch: amd64
dmidecode:
  not-arch: ppc64, ppc64le
lshw:
  arch: ppc64, ppc64le
python-dev:
  dib_python_version: 2
python3-dev:
  dib_python_version: 3
libssl-dev:
  build-only: True
package-a:
  when: DIB_USE_PACKAGE_A = 1
package-b:
  when: DIB_USE_PACKAGE_A != 1

example package-installs.json

{
"libxml2": null,
"grub2": {"phase": "pre-install.d"},
"networkmanager": {"uninstall": true}
"os-collect-config": {"installtype": "source"}
}

Setting phase, uninstall, or installtype properties for a package overrides the following default values:

phase: install.d
uninstall: False
installtype: * (Install package for all installtypes)
arch: * (Install package for all architectures)
dib_python_version: (2 or 3 depending on DIB_PYTHON_VERSION, see dib-python)

Setting the installtype property causes the package only to be installed if the specified installtype would be used for the element. See the diskimage-builder docs for more information on installtypes.

Setting build-only will cause the package to be added both to the list of packages to be installed and to the list of packages to be uninstalled. This allows expressing build-time dependencies that should not end up in the final image.

The arch property is a comma-separated list of architectures to install for. The not-arch is a comma-separated list of architectures the package should be excluded from. Either arch or not-arch can be given for one package - not both. See documentation about the ARCH variable for more information.

The when property is a simple = or != match on a value in an environment variable. If the given environment variable matches the operation and value, the package is installed. If the variable is not available in the environment, an exception is raised (thus defaults will likely need to be provided in environment.d files or similar for flags used here). For example, to install an extra package when a feature is enabled:

package:
  when: DIB_FEATURE_FLAG=1

To install package when DIB_FEATURE_FLAG=0 but other_package when DIB_FEATURE_FLAG=1 (i.e. toggle between two packages), you can use something like:

package:
  when: DIB_FEATURE_FLAG=0
other_package:
  when: DIB_FEATURE_FLAG!=0

You can also use a list of items in the when statement, which will be effectively combined with and.

If you need to filter multiple paths for a single package, you can make the parameters a list. For example, if linux-image-generic package should be installed when DIB_UBUNTU_KERNEL = linux-image-generic is set except on arm64 Xenial hosts, where we would like to install linux-generic-hwe-16.04 you could use the following:

linux-image-generic:
 - not-arch: arm64
   when: DIB_UBUNTU_KERNEL = linux-image-generic
 - arch: arm64
   when:
    - DIB_RELEASE != xenial
    - DIB_UBUNTU_KERNEL = linux-image-generic

linux-generic-hwe-16.04:
  arch: arm64
  when:
   - DIB_RELEASE = xenial
   - DIB_UBUNTU_KERNEL = linux-image-generic

DEPRECATED: Adding a file under your elements pre-install.d, install.d, or post-install.d directories called package-installs-<element-name> will cause the list of packages in that file to be installed at the beginning of the respective phase. If the package name in the file starts with a "-", then that package will be removed at the end of the install.d phase.

Using post-install.d for cleanup

Package removal is done in post-install.d at level 95. If you a running cleanup functions before this, you need to be careful not to clean out any temporary files relied upon by this element. For this reason, generally post-install cleanup functions should occupy the higher levels between 96 and 99.