[PATCH v5 1/4] isar-bootstrap|configscript: implement one transient packages

[claudius.heine.ext@siemens.com]

From: Claudius Heine <ch@denx.de>

Some configuration tasks on the image require certain other packages,
but those packages might not be required on the final image.

One way to solve this is use a special package that is installed to the
image and then removed again. When installing it makes certain that all
required packages are installed to the image as well. Then the image
can be configured in the postinst hook. When this package is removed and
all unused dependencies are removed as well, no not required packages
used by this package should remain on the image.

Signed-off-by: Claudius Heine <ch@denx.de>
---
 .../images/files/debian-configscript.sh       |  1 -
 .../images/files/raspbian-configscript.sh     |  1 -
 meta/classes/isar-bootstrap-helper.bbclass    | 32 ++++++++++++++++---
 3 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/meta-isar/recipes-core/images/files/debian-configscript.sh b/meta-isar/recipes-core/images/files/debian-configscript.sh
index 7ca0562..9b3ff30 100755
--- a/meta-isar/recipes-core/images/files/debian-configscript.sh
+++ b/meta-isar/recipes-core/images/files/debian-configscript.sh
@@ -40,4 +40,3 @@ fi
 
 # Purge unused locale and installed packages' .deb files
 localepurge
-apt-get clean
diff --git a/meta-isar/recipes-core/images/files/raspbian-configscript.sh b/meta-isar/recipes-core/images/files/raspbian-configscript.sh
index b240de9..448dea5 100644
--- a/meta-isar/recipes-core/images/files/raspbian-configscript.sh
+++ b/meta-isar/recipes-core/images/files/raspbian-configscript.sh
@@ -40,4 +40,3 @@ kernel=$KERNEL_IMAGE
 EOF
 
 localepurge
-apt-get clean
diff --git a/meta/classes/isar-bootstrap-helper.bbclass b/meta/classes/isar-bootstrap-helper.bbclass
index 4284d02..d6b2a26 100644
--- a/meta/classes/isar-bootstrap-helper.bbclass
+++ b/meta/classes/isar-bootstrap-helper.bbclass
@@ -5,15 +5,24 @@
 #
 # SPDX-License-Identifier: MIT
 
+IMAGE_TRANSIENT_PACKAGES ??= ""
+
+def reverse_bb_array(d, varname):
+    array = d.getVar(varname, True)
+    if array is None:
+        return None
+    array = reversed(array.split())
+    return " ".join(i for i in array)
+
 setup_root_file_system() {
     ROOTFSDIR="$1"
-    CLEANHOSTLEAK="$2"
+    CLEAN="$2"
     shift
     shift
     PACKAGES="$@"
     APT_ARGS="install --yes --allow-unauthenticated \
               -o Debug::pkgProblemResolver=yes"
-    CLEANHOSTLEAK_FILES="${ROOTFSDIR}/etc/hostname ${ROOTFSDIR}/etc/resolv.conf"
+    CLEAN_FILES="${ROOTFSDIR}/etc/hostname ${ROOTFSDIR}/etc/resolv.conf"
 
     sudo cp -Trpfx \
         "${DEPLOY_DIR_IMAGE}/isar-bootstrap-${DISTRO}-${DISTRO_ARCH}/" \
@@ -41,8 +50,23 @@ setup_root_file_system() {
         -o Dir::Etc::sourceparts="-" \
         -o APT::Get::List-Cleanup="0"
     sudo -E chroot "$ROOTFSDIR" \
-        /usr/bin/apt-get ${APT_ARGS} --download-only $PACKAGES
-    [ "clean" = ${CLEANHOSTLEAK} ] && sudo rm -f ${CLEANHOSTLEAK_FILES}
+        /usr/bin/apt-get ${APT_ARGS} --download-only $PACKAGES \
+            ${IMAGE_TRANSIENT_PACKAGES}
+    [ "clean" = ${CLEAN} ] && sudo rm -f ${CLEAN_FILES}
     sudo -E chroot "$ROOTFSDIR" \
         /usr/bin/apt-get ${APT_ARGS} $PACKAGES
+    for pkg in ${IMAGE_TRANSIENT_PACKAGES}; do
+        sudo -E chroot "$ROOTFSDIR" \
+            /usr/bin/apt-get ${APT_ARGS} $pkg
+    done
+    for pkg in ${@reverse_bb_array(d, "IMAGE_TRANSIENT_PACKAGES") or ""}; do
+        sudo -E chroot "$ROOTFSDIR" \
+            /usr/bin/apt-get purge --yes $pkg
+    done
+    if [ "clean" = ${CLEAN} ]; then
+        sudo -E chroot "$ROOTFSDIR" \
+            /usr/bin/apt-get autoremove --purge --yes
+        sudo -E chroot "$ROOTFSDIR" \
+            /usr/bin/apt-get clean
+    fi
 }
-- 
2.17.0