[PATCH v3 2/2] classes/image-postproc: Enable systemd units based on systemd presets

["alexander.heinisch via isar-users" <isar-users@googlegroups.com>]

From: Alexander Heinisch <alexander.heinisch@siemens.com>

By default population of the presets is automatically done by systemd
on first-boot.

There were several issues with that:

1. The rootfs we get as a build artifact does not reflect the actual
system running in the field.

2. For setups without writeable /etc this fails. With that addition
it happens already at build time.

Note: Additional services are enabled only. Services already enabled
during the package installation won't be changed.

Opt-out: `ROOTFS_FEATURES:remove = "populate-systemd-preset"`

Signed-off-by: Alexander Heinisch <alexander.heinisch@siemens.com>
---
 RECIPE-API-CHANGELOG.md     | 18 ++++++++++++++++++
 meta/classes/image.bbclass  |  1 +
 meta/classes/rootfs.bbclass |  6 ++++++
 3 files changed, 25 insertions(+)

diff --git a/RECIPE-API-CHANGELOG.md b/RECIPE-API-CHANGELOG.md
index 92e7811c..f2e21088 100644
--- a/RECIPE-API-CHANGELOG.md
+++ b/RECIPE-API-CHANGELOG.md
@@ -741,3 +741,21 @@ By setting `MS_TPM_20_REF_DIR` in an optee-ftpm recipe, it is now possible to
 use the new optee_ftpm code base from the OP-TEE project. That variable has to
 point to a subdir in `WORKDIR` which contains the unpacked ms-tpm-20-ref source
 code.
+
+### Populate systemd units based on presets during image postprocessing
+
+By default population of the presets is automatically done by systemd
+on first-boot.
+
+There were several issues with that:
+
+1. The rootfs we get as a build artifact does not reflect the actual
+system running in the field.
+
+2. For setups without writeable /etc this fails. With that addition
+it happens already at build time.
+
+**Note**: Additional services are enabled only. Services already enabled
+during the package installation won't be changed.
+
+Opt-out: `ROOTFS_FEATURES:remove = "populate-systemd-preset"`
diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index d833564f..44b59420 100644
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -73,6 +73,7 @@ ROOTFS_FEATURES += "\
     export-dpkg-status \
     clean-log-files \
     clean-debconf-cache \
+    populate-systemd-preset \
     "
 # when using a custom initrd, do not generate one as part of the image rootfs
 ROOTFS_FEATURES += "${@ '' if d.getVar('INITRD_IMAGE') == '' else 'no-generate-initrd'}"
diff --git a/meta/classes/rootfs.bbclass b/meta/classes/rootfs.bbclass
index ebe3bf4a..fdfad2fa 100644
--- a/meta/classes/rootfs.bbclass
+++ b/meta/classes/rootfs.bbclass
@@ -15,6 +15,7 @@ ROOTFS_BASE_DISTRO ?= "${BASE_DISTRO}"
 # 'export-dpkg-status' - exports /var/lib/dpkg/status file to ${ROOTFS_DPKGSTATUS_DEPLOY_DIR}
 # 'clean-log-files' - delete log files that are not owned by packages
 # 'no-generate-initrd' - do not generate debian default initrd
+# 'populate-systemd-preset' - enable systemd units according to systemd presets
 ROOTFS_FEATURES ?= ""
 
 ROOTFS_APT_ARGS="install --yes -o Debug::pkgProblemResolver=yes"
@@ -429,6 +430,11 @@ rootfs_cleanup_base_apt() {
 EOSUDO
 }
 
+ROOTFS_POSTPROCESS_COMMAND += "${@bb.utils.contains('ROOTFS_FEATURES', 'populate-systemd-preset', 'image_postprocess_populate_systemd_preset', '', d)}"
+image_postprocess_populate_systemd_preset() {
+    sudo chroot '${ROOTFSDIR}' systemctl preset-all --preset-mode="enable-only"
+}
+
 do_rootfs_postprocess[vardeps] = "${ROOTFS_POSTPROCESS_COMMAND}"
 do_rootfs_postprocess[network] = "${TASK_USE_SUDO}"
 python do_rootfs_postprocess() {
-- 
2.39.5

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