Re: [isar] rootfs: Add new ROOTFS_FEATURE 'slimfy' to minimize the footprint

[Henning Schild <henning.schild@siemens.com>]

IMHO no need to model that as a feature. Removing "temporary" files
that do not belong to packages is something everybody would expect
anyways.

Am Mon, 6 Sep 2021 15:15:10 +0530
schrieb <venkata.pyla@toshiba-tsip.com>:

> From: venkata pyla <venkata.pyla@toshiba-tsip.com>
> 
>  This Adds new ROOTFS_FEATURE 'slimify' that deletes unnecessary files
>  in the rootfs and contributes to minimal footprint in the rootfs and
>  also avoids the reproducible failures due to non-deterministic data
> in the log files and temporary files.
> 
>  It deletes the following files
>   - /var/log/*
>   - /tmp/*
> 
>  To enable this feature
>    ROOTFS_FEATURE += slimify
> 
> Signed-off-by: venkata pyla <venkata.pyla@toshiba-tsip.com>
> ---
>  meta/classes/rootfs.bbclass | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/meta/classes/rootfs.bbclass b/meta/classes/rootfs.bbclass
> index f9151c5..d01a9d1 100644
> --- a/meta/classes/rootfs.bbclass
> +++ b/meta/classes/rootfs.bbclass
> @@ -12,6 +12,7 @@ ROOTFS_PACKAGES ?= ""
>  # 'clean-package-cache' - delete package cache from rootfs
>  # 'generate-manifest' - generate a package manifest of the rootfs
> into ${ROOTFS_MANIFEST_DEPLOY_DIR} # 'export-dpkg-status' - exports
> /var/lib/dpkg/status file to ${ROOTFS_DPKGSTATUS_DEPLOY_DIR} +#
> 'slimify'            - delete unnecessary files in rootfs like
> /var/log/*, /tmp/* ROOTFS_FEATURES ?= "" 
>  ROOTFS_APT_ARGS="install --yes -o Debug::pkgProblemResolver=yes"
> @@ -229,6 +230,12 @@ rootfs_export_dpkg_status() {
>         '${ROOTFS_DPKGSTATUS_DEPLOY_DIR}'/'${PF}'.dpkg_status
>  }
>  
> +ROOTFS_POSTPROCESS_COMMAND +=
> "${@bb.utils.contains('ROOTFS_FEATURES', 'slimify', 'rootfs_slimify',
> '', d)}" +rootfs_slimify() {
> +    sudo rm -rf "${ROOTFSDIR}/var/log/"*

This is going too far because you are removing package content i.e.
  dpkg -S /var/log/apt
  apt: /var/log/apt

If packages ship directories or maybe even files we can not simply
delete those.

And overall the change is not going far enough. Because i.e. /var/lib
and /var/cache remain as problems.
Instead of listing a bunch of directories we should really go and ask
the package manager which files are without owner.

Henning


> +    sudo rm -rf "${ROOTFSDIR}/tmp/"*
> +}
> +
>  do_rootfs_postprocess[vardeps] = "${ROOTFS_POSTPROCESS_COMMAND}"
>  python do_rootfs_postprocess() {
>      # Take care that its correctly mounted: