[RFC 1/2] meta/classes: Add remove packages to rootfs postprocessing

["Q. Gylstorff" <Quirin.Gylstorff@siemens.com>]

From: Quirin Gylstorff <quirin.gylstorff@siemens.com>

Remove non-essential packages to reduce the amount of packages
to be cleared. It can also to used to reduce the foot print
of a image.

Signed-off-by: Quirin Gylstorff <quirin.gylstorff@siemens.com>
---
 meta/classes/image.bbclass  |  2 +-
 meta/classes/rootfs.bbclass | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index 6bcc6cd..62d6f46 100644
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -60,7 +60,7 @@ image_do_mounts() {
 }
 
 ROOTFSDIR = "${IMAGE_ROOTFS}"
-ROOTFS_FEATURES += "copy-package-cache clean-package-cache finalize-rootfs generate-manifest"
+ROOTFS_FEATURES += "copy-package-cache clean-package-cache finalize-rootfs generate-manifest remove_packages"
 ROOTFS_PACKAGES += "${IMAGE_PREINSTALL} ${IMAGE_INSTALL}"
 ROOTFS_MANIFEST_DEPLOY_DIR ?= "${DEPLOY_DIR_IMAGE}"
 
diff --git a/meta/classes/rootfs.bbclass b/meta/classes/rootfs.bbclass
index 64eaef7..0329f55 100644
--- a/meta/classes/rootfs.bbclass
+++ b/meta/classes/rootfs.bbclass
@@ -187,6 +187,19 @@ rootfs_postprocess_clean_package_cache() {
         /usr/bin/apt-get clean
     sudo rm -rf "${ROOTFSDIR}/var/lib/apt/lists/"*
 }
+ROOTFS_POSTPROCESS_COMMAND += "${@bb.utils.contains('ROOTFS_FEATURES', 'remove_packages', 'rootfs_rm_packages', '', d)}"
+rootfs_rm_packages () {
+    if [ -n "${ROOTFS_PACKAGES_FORCE_REMOVE}" ]; then
+        RMPKGS=$(sudo -E chroot "${ROOTFSDIR}" \
+              dpkg-query \
+              -f '${Package}\n' \
+              -W ${ROOTFS_PACKAGES_FORCE_REMOVE} 2>/dev/null || true)
+    fi
+    if [ -n "${RMPKGS}" ]; then
+        sudo -E chroot "${ROOTFSDIR}" \
+            dpkg --purge --force-depends ${RMPKGS}
+    fi
+}
 
 ROOTFS_POSTPROCESS_COMMAND += "${@bb.utils.contains('ROOTFS_FEATURES', 'generate-manifest', 'rootfs_generate_manifest', '', d)}"
 rootfs_generate_manifest () {
-- 
2.20.1