Re: [RFC PATCH 2/2] recipes-core: Add recipe for base-files

[Jan Kiszka <jan.kiszka@siemens.com>]

On 25.02.21 06:08, vijaikumar....@gmail.com wrote:
> 
> 
> On Thursday, February 25, 2021 at 9:27:51 AM UTC+5:30
> vijaikumar....@gmail.com wrote:
> 
>     On Wed, Feb 24, 2021 at 5:43 PM Henning Schild
>     <henning...@siemens.com> wrote:
>     >
>     > Am Tue, 23 Feb 2021 14:08:29 +0530
>     > schrieb vijai kumar <vijaikumar....@gmail.com>:
>     >
>     > > On Sat, Feb 20, 2021 at 1:59 PM Henning Schild
>     > > <henning...@siemens.com> wrote:
>     > > >
>     > > > Am Sat, 20 Feb 2021 01:27:19 +0530
>     > > > schrieb Vijai Kumar K <Vijaikumar_...@mentor.com>:
>     > > >
>     > > > > /etc/os-release is a symlink to /usr/lib/os-release and
>     belongs to
>     > > > > the base-files package.
>     > > > >
>     > > > > ISAR has been modifying the /etc/os-release during
>     postprocessing
>     > > > > to inject custom data onto it.
>     > > > >
>     > > > > Since this file belongs to base-files, an update/reinstall
>     of the
>     > > > > package would overwrite the file with the one provided by
>     > > > > base-files.
>     > > >
>     > > > To some degree such an update would be right to do so. The
>     BUILD_ID
>     > > > will for sure be invalidated, other custom fields might still be
>     > > > valid though.
>     > > >
>     > > > > Instead of modifying the contents of /etc/os-release during
>     > > > > post-processing, provide a modified base-files recipe in ISAR
>     > > > > which provides the similar changes in os-release.
>     > > >
>     > > > I am beginning to wonder if we have to write certain bits to
>     other
>     > > > files. Bits that need to go into /etc/os-release could be
>     appended
>     > > > with a hook
>     > > > See isar-disable-apt-cache, or we use the divert that Silvano
>     > > > proposed.
>     > >
>     > > I have not used hooks before, but looks like it might help in our
>     > > case.
>     > >
>     > > >
>     > > > > Signed-off-by: Vijai Kumar K <Vijaikumar_...@mentor.com>
>     > > > > ---
>     > > > > .../recipes-core/images/isar-image-base.bb
>     <http://isar-image-base.bb> | 2 +
>     > > > > meta/classes/image-postproc-extension.bbclass | 40
>     --------------
>     > > > > meta/classes/image.bbclass | 20 -------
>     > > > > meta/recipes-core/base-files/base-files.bb
>     <http://base-files.bb> | 6 ++
>     > > > > meta/recipes-core/base-files/base-files.inc | 55
>     > > > > +++++++++++++++++++ 5 files changed, 63 insertions(+), 60
>     > > > > deletions(-) create mode 100644
>     > > > > meta/recipes-core/base-files/base-files.bb
>     <http://base-files.bb> create mode 100644
>     > > > > meta/recipes-core/base-files/base-files.inc
>     > > > >
>     > > > > diff --git
>     a/meta-isar/recipes-core/images/isar-image-base.bb
>     <http://isar-image-base.bb>
>     > > > > b/meta-isar/recipes-core/images/isar-image-base.bb
>     <http://isar-image-base.bb> index
>     > > > > b381d85..4aa7e66 100644 ---
>     > > > > a/meta-isar/recipes-core/images/isar-image-base.bb
>     <http://isar-image-base.bb> +++
>     > > > > b/meta-isar/recipes-core/images/isar-image-base.bb
>     <http://isar-image-base.bb> @@ -11,3 +11,5
>     > > > > @@ LIC_FILES_CHKSUM =
>     > > > >
>     "file://${LAYERDIR_core}/licenses/COPYING.GPLv2;md5=751419260 PV =
>     > > > > "1.0" inherit image
>     > > > > +
>     > > > > +IMAGE_INSTALL += "base-files"
>     > > > > diff --git a/meta/classes/image-postproc-extension.bbclass
>     > > > > b/meta/classes/image-postproc-extension.bbclass index
>     > > > > 3f00c21..22c6a95 100644 ---
>     > > > > a/meta/classes/image-postproc-extension.bbclass +++
>     > > > > b/meta/classes/image-postproc-extension.bbclass @@ -1,38
>     +1,6 @@
>     > > > > # This software is a part of ISAR.
>     > > > > # Copyright (C) Siemens AG, 2019
>     > > > >
>     > > > > -update_etc_os_release() {
>     > > > > - OS_RELEASE_BUILD_ID=""
>     > > > > - OS_RELEASE_VARIANT=""
>     > > > > - OS_RELEASE_VARIANT_VERSION=""
>     > > > > - while true; do
>     > > > > - case "$1" in
>     > > > > - --build-id) OS_RELEASE_BUILD_ID=$2; shift ;;
>     > > > > - --variant) OS_RELEASE_VARIANT=$2; shift ;;
>     > > > > - --version) OS_RELEASE_VARIANT_VERSION=$2; shift ;;
>     > > > > - -*) bbfatal "$0: invalid option specified: $1" ;;
>     > > > > - *) break ;;
>     > > > > - esac
>     > > > > - shift
>     > > > > - done
>     > > > > -
>     > > > > - if [ -n "${OS_RELEASE_BUILD_ID}" ]; then
>     > > > > - sudo sed -i '/^BUILD_ID=.*/d'
>     > > > > '${IMAGE_ROOTFS}/etc/os-release'
>     > > > > - echo "BUILD_ID=\"${OS_RELEASE_BUILD_ID}\"" | \
>     > > > > - sudo tee -a '${IMAGE_ROOTFS}/etc/os-release'
>     > > > > - fi
>     > > > > - if [ -n "${OS_RELEASE_VARIANT}" ]; then
>     > > > > - sudo sed -i '/^VARIANT=.*/d'
>     > > > > '${IMAGE_ROOTFS}/etc/os-release'
>     > > > > - echo "VARIANT=\"${OS_RELEASE_VARIANT}\"" | \
>     > > > > - sudo tee -a '${IMAGE_ROOTFS}/etc/os-release'
>     > > > > - fi
>     > > > > - if [ -n "${OS_RELEASE_VARIANT_VERSION}" ]; then
>     > > > > - sudo sed -i '/^ISAR_IMAGE_VERSION=.*/d'
>     > > > > '${IMAGE_ROOTFS}/etc/os-release'
>     > > > > - echo "VARIANT_VERSION=\"${PV}\"" | \
>     > > > > - sudo tee -a '${IMAGE_ROOTFS}/etc/os-release'
>     > > > > - fi
>     > > > > -}
>     > > >
>     > > > This is in the image for a good reason, it can not be part of a
>     > > > package, otherwise it would already be and we might not have that
>     > > > evil postprocess feature.
>     > > >
>     > > > Try a run, append a package to IMAGE_PREINSTALL, build again
>     > > >
>     > > > I kind of bet that BUILD_ID will be wrong and not show your new
>     > > > commit or "dirty"
>     > >
>     > > Yes, It is wrong.
>     > >
>     > > Since we definitely know that we are bringing in a variable
>     > > that changes everytime when there is a change to the source
>     code, we
>     > > could very well do do_prepare_build[nostamp]="1".
>     > >
>     > > That with some changes should solve this problem.
>     >
>     > It will mean that every change will trigger a full reinstall of the
>     > image, many changes do that, but it sounds bad.
>     >
>     > And the false-sharing between images and multiconfigs still remains.
>     >
>     > Try two images in one layer with differing DESCRIPTIONS and see what
>     > happens. That would be the simple case without even thinking mc
> 
>     So basically os-release varies based on the image built. With a
>     single package
>     like this, it is no longer possible. At anypoint we could have only
>     one version
>     of the package.
> 
> 
> Basically we just considered each image to be a "derivative" . Which I
> don't suppose
> is the case, at least with upstream ISAR.
>  
> 
> 
>     Then, again, it makes me wonder if os-release is an apt place for such
>     information.
>     We lose updatability with the other approach. We definitely leave one
>     file (/etc/os-release or /usr/lib/os-release)
>     outdated on a dist upgrade. 
> 

So far, we did not consider os-release in package-based update scenarios
(likely because all our updates were partition based - which doesn't
mean package-based will not come one day as well). If we include
package-based updates, os-release should be updated by a package as well.

Our os-release modification (ISAR_RELEASE_CMD) is bound to an image. An
image is not a package, but we could make it depend on an image-specific
package carrying or generating that os-release data. That package should
definitely NOT be base-files. We need to divert that file and keep it
under our control. Obviously, if the user decides to do a an upgrade of
the Debian version on the device without pulling a new image version
package, things will really divert - but that is no reasonable use case
IMHO.

Jan

-- 
Siemens AG, T RDA IOT
Corporate Competence Center Embedded Linux