Re: [PATCH v4 2/2] meta: cache deb srcs as part of postprocessing

[vijai kumar <vijaikumar.kanagarajan@gmail.com>]

On Wed, Apr 15, 2020 at 11:50 PM Henning Schild
<henning.schild@siemens.com> wrote:
>
> On Wed, 15 Apr 2020 17:59:12 +0530
> vijai kumar <vijaikumar.kanagarajan@gmail.com> wrote:
>
> > On Wed, Apr 8, 2020 at 6:00 PM Henning Schild
> > <henning.schild@siemens.com> wrote:
> > >
> > > Am Wed, 8 Apr 2020 16:07:15 +0530
> > > schrieb vijai kumar <vijaikumar.kanagarajan@gmail.com>:
> > >
> > > > On Wed, Apr 8, 2020 at 3:34 PM Henning Schild
> > > > <henning.schild@siemens.com> wrote:
> > > > >
> > > > > Am Fri, 3 Apr 2020 18:35:51 +0530
> > > > > schrieb Vijai Kumar K <vijaikumar.kanagarajan@gmail.com>:
> > > > >
> > > > > > Collect the deb sources of the corresponding deb binaries
> > > > > > cached in DEBDIR as part of postprocess for those to be later
> > > > > > included into the final base-apt by do_cache.
> > > > > >
> > > > > > Signed-off-by: Vijai Kumar K
> > > > > > <Vijaikumar_Kanagarajan@mentor.com> ---
> > > > > >  meta/classes/image.bbclass  |  2 +-
> > > > > >  meta/classes/rootfs.bbclass | 46
> > > > > > +++++++++++++++++++++++++++++++++++++ 2 files changed, 47
> > > > > > insertions(+), 1 deletion(-)
> > > > > >
> > > > > > diff --git a/meta/classes/image.bbclass
> > > > > > b/meta/classes/image.bbclass index 9fa58f8..1c7a527 100644
> > > > > > --- a/meta/classes/image.bbclass
> > > > > > +++ b/meta/classes/image.bbclass
> > > > > > @@ -60,7 +60,7 @@ image_do_mounts() {
> > > > > >  }
> > > > > >
> > > > > >  ROOTFSDIR = "${IMAGE_ROOTFS}"
> > > > > > -ROOTFS_FEATURES += "copy-package-cache clean-package-cache
> > > > > > generate-manifest" +ROOTFS_FEATURES += "copy-package-cache
> > > > > > clean-package-cache generate-manifest cache-deb-src"
> > > > > > ROOTFS_PACKAGES += "${IMAGE_PREINSTALL} ${IMAGE_INSTALL}"
> > > > > > ROOTFS_MANIFEST_DEPLOY_DIR ?= "${DEPLOY_DIR_IMAGE}"
> > > > > > diff --git a/meta/classes/rootfs.bbclass
> > > > > > b/meta/classes/rootfs.bbclass index 8bb003d..7bfdfc9 100644
> > > > > > --- a/meta/classes/rootfs.bbclass
> > > > > > +++ b/meta/classes/rootfs.bbclass
> > > > > > @@ -201,6 +201,52 @@ rootfs_generate_manifest () {
> > > > > >          ${ROOTFS_MANIFEST_DEPLOY_DIR}/"${PF}".manifest
> > > > > >  }
> > > > > >
> > > > > > +ROOTFS_POSTPROCESS_COMMAND +=
> > > > > > "${@bb.utils.contains('ROOTFS_FEATURES', 'cache-deb-src',
> > > > > > 'cache_deb_src', '', d)}" +cache_deb_src() {
> > > > > > +    if [ "${ISAR_USE_CACHED_BASE_REPO}" = "1" ]; then
> > > > > > +        return 0
> > > > > > +    fi
> > > > >
> > > > > Should the source packages not all end up in the cache, so they
> > > > > can and probably should be fetched from there.
> > > >
> > > > Sorry. But I am not able to understand this. Can you please
> > > > explain it again?
> > >
> > > A first build without the cache will fetch all sources and drop them
> > > into "${DEBSRCDIR}"/"${DISTRO}", just the the apt:// fetcher does.
> > > A second build with an enabled cache will place all those src-pkgs
> > > in base-apt (see populate_base_apt repo_add_srcpackage loop).
> > >
> > > So a second run of this function here should be able to fetch all
> > > those srcs-pkgs from base-apt. And it would be a good idea to
> > > actually do that to prove that everything is available offline.
> > >
> > > Note that for real offline BB_NO_NETWORK would be required. And that
> > > "guard" should still be able to download from base-apt. Thinking
> > > about it again ... i think you do not need the guard. If all
> > > src-pkgs are available offline this function will never access the
> > > internet, if it still tries the invalid proxy "guard" from
> > > isar_export_proxies will trigger.
> > >
> > > I think it boils down to removing the
> > > [ "${ISAR_USE_CACHED_BASE_REPO}" = "1" ] && exit 0
> > > and passing the ci offline/cache test
> > >
> > > > >
> > > > > > +    mkdir -p "${DEBSRCDIR}"/"${DISTRO}"
> > > > > > +
> > > > > > +    sudo -s <<'EOSUDO'
> > > > > > +    cp -L /etc/resolv.conf '${ROOTFSDIR}/etc'
> > > > > > +    mkdir -p '${ROOTFSDIR}/deb-src'
> > > > > > +    mountpoint -q '${ROOTFSDIR}/deb-src' || \
> > > > > > +    mount --bind '${DEBSRCDIR}' '${ROOTFSDIR}/deb-src'
> > > > > > +EOSUDO
> > > > > > +
> > > > > > +    sudo -E chroot ${ROOTFSDIR} /usr/bin/apt-get update
> > >
> > > Why is that in here? Doing this in the image is not allowed, only
> > > for isar-apt!
> >
> > Hi Henning,
> >
> > I am sorry. But why is it not allowed? Am I missing any side effects
> > of this call?
>
> Thanks for asking, please keep doing that when things are unclear.

Sure. Definitely.

>
> An "update" stores a copy of the "view on the repo world" in the image.
> It is essentially a copy of the Packages.gz or Sources.gz of all repos.
> That information changes over time on the servers, while they still
> (hopefully) offer to download packages referenced in older version of
> those indexes.
>
> Isar relies on that. It fetches all indexes exactly once and later
> downloads packages found in the cached versions. Once you update an
> index the "view of the world" moves away from "the state of the image".
>
> On a living debian system you would always upgrade packages after
> update-ing the indexes. In an "installer" - like Isar - you probably do
> not want those dynamics.
>
> So in order to keep "the state of the image" and "the view of the
> world" in sync we never "apt-get update" ... except for isar-apt which
> is a repo we can/do control.
>
> If a build takes a really long time, there is a slim chance that we can
> not actually fetch packages found in our old indexes because upstream
> does not provide them anymore. I have not seen real evidence of that
> potential problem. It could however manifest if we have a long running
> build ... arm without cross ... and do additional fetches in postinst
> ... like you are implementing.
> But whatever you can not fetch in the end, is probably not worth
> fetching because it is not what was used to construct your image.

Thank you for the explanation Henning. It would be good if this
information is documented somewhere. ;)

Best,
Vijai Kumar K


>
> Henning
>
> > Thanks,
> > Vijai Kumar K
> >
> > >
> > > > > > +    find "${DEBDIR}"/"${DISTRO}" -name '*\.deb' | while read
> > > > > > package; do
> > >
> > > You are reading this without grabbing the lock. In multiconfig other
> > > images might be filling that directory as you read it. And you
> > > might be calling dpkg-deb on half copied files.
> > >
> > > Try deb_dl_dir_import and looping over /var/cache/apt/archives/ ...
> > > in which case you will find yourself dealing with isar-apt packages
> > > that you need to skip.
> > > In fact you should use the manifest as input to not download
> > > packages installed in other images with the same distro but without
> > > the feature.
> > >
> > > Yeahh multiconfig!
> > >
> > > Henning
> > >
> > > > > > +        local src="$( dpkg-deb --show --showformat
> > > > > > '${Source}' "${package}" )"
> > > > > > +        # If the binary package version and source package
> > > > > > version are different, then the
> > > > > > +        # source package version will be present inside "()"
> > > > > > of the Source field.
> > > > > > +        local version="$( echo "$src" | cut -sd "(" -f2 |
> > > > > > cut -sd ")" -f1 )"
> > > > > > +        if [ -z ${version} ]; then
> > > > > > +            version="$( dpkg-deb --show --showformat
> > > > > > '${Version}' "${package}" )"
> > > > > > +        fi
> > > > > > +        # Now strip any version information that might be
> > > > > > available.
> > > > > > +        src="$( echo "$src" | cut -d' ' -f1 )"
> > > > > > +        # If there is no source field, then the source
> > > > > > package has the same name as the
> > > > > > +        # binary package.
> > > > > > +        if [ -z "${src}" ];then
> > > > > > +            src="$( dpkg-deb --show --showformat '${Package}'
> > > > > > "${package}" )"
> > > > > > +        fi
> > > > > > +
> > > > > > +        sudo -E chroot --userspec=$( id -u ):$( id -g )
> > > > > > ${ROOTFSDIR} \
> > > > > > +            sh -c 'mkdir -p "/deb-src/${1}/${2}" && cd
> > > > > > "/deb-src/${1}/${2}" && \
> > > > > > +                apt-get -y --download-only --only-source
> > > > > > source "$2"="$3"' \
> > > > > > +                download-src "${DISTRO}" "${src}"
> > > > > > "${version}"
> > > > > > +    done
> > > > >
> > > > > Looks like we are going online without proxy configuration
> > > > > here. It also needs a BB_NO_NETWORK guard.
> > > >
> > > > Will take care of that.
> > > >
> > > > >
> > > > > And i would suggest to generate the list of things you want to
> > > > > fetch, factor out the fetcher from dpkg-base and reuse is
> > > > > instead of copying it.
> > > >
> > > > Sure. I will have a look into how I can reuse that part.
> > > >
> > > > >
> > > > > And i would personally like a new series of patches to be sent
> > > > > without "in-reply-to". Maybe its my client but i find these
> > > > > deeply nested threads very hard to follow.
> > > >
> > > > No Problem. Will send the next series separately.
> > > >
> > > > Thanks,
> > > > Vijai Kumar K
> > > >
> > > > >
> > > > > Henning
> > > > >
> > > > > > +    sudo -s <<'EOSUDO'
> > > > > > +    mountpoint -q '${ROOTFSDIR}/deb-src' && \
> > > > > > +    umount -l ${ROOTFSDIR}/deb-src
> > > > > > +    rm -rf '${ROOTFSDIR}/etc/resolv.conf'
> > > > > > +EOSUDO
> > > > > > +}
> > > > > > +
> > > > > >  do_rootfs_postprocess[vardeps] =
> > > > > > "${ROOTFS_POSTPROCESS_COMMAND}" python
> > > > > > do_rootfs_postprocess() { # Take care that its correctly
> > > > > > mounted:
> > > > >
> > >
>