Add image specific optional volatile log handling

Signed-off-by: Andreas Müller <schnitzeltony@gmail.com>

README

@@ -33,6 +33,17 @@ Additionally this layer checks the following variable in local.conf:
     Set MORTSGNA_ARMV7_TUNE="1"
   * If you are intersted in best optimization for your machine and/or you have
     a fast build host with lots of disk-space: don't!
+  see conf/distro/include/mortsgna-armv7-tune.inc for more information
+
+-------------------------------------------------------------------------------
+The following image specific variables are handled:
+
+* MORTSGNA_IMAGE_VOLATILE_LOG_DIR
+  * If set to "1", journal goes to volatile /run/log and /var/log is linked to
+    /run/log which is volatile
+  * Otherwise all log goes to /var/log which is persistent
+  see conf/distro/include/mortsgna-image-logfile-volatile.inc for more
+  information
 
 -------------------------------------------------------------------------------
 This layer contains the following folders:
@@ -43,7 +54,7 @@ appends:
   for the layer is ignored (see conf/layer.conf).
 
 classes:
-  Currently instant-remote.bbclass and user-with-full-skel.bbclass.
+  Our classes to tailor build.
 
 conf:
   layer.conf / and distro configurations

conf/distro/include/mortsgna-image-logfile-volatile.inc

@@ -0,0 +1,22 @@
+# override bitbake.conf default
+VOLATILE_LOG_DIR = "false"
+
+# Do alignment on journal and /var/log
+ROOTFS_POSTPROCESS_COMMAND += "postinst_volatile_log; "
+
+postinst_volatile_log () {
+    if [ "${MORTSGNA_IMAGE_VOLATILE_LOG_DIR}" = "1" ]; then
+        # systemd journal
+        if [ -f "${IMAGE_ROOTFS}${sysconfdir}/systemd/journald.conf" ]; then
+            sed -i \
+                -e 's:.*Storage=.*:Storage=volatile:g' \
+                ${IMAGE_ROOTFS}${sysconfdir}/systemd/journald.conf
+        fi
+        # link /var/log -> /run/log
+        if [ -e ${IMAGE_ROOTFS}${localstatedir}/log ]; then
+             rm -rf ${IMAGE_ROOTFS}${localstatedir}/log
+        fi
+        ln -sf ../run/log ${IMAGE_ROOTFS}${localstatedir}/log
+    fi
+}
+

conf/distro/include/mortsgna.inc

@@ -116,5 +116,8 @@ DISTRO_FEATURES += "${DISTRO_WAYLAND}"
 # Inherit the default LIBC features superset from OE-core
 DISTRO_FEATURES += "${DISTRO_FEATURES_LIBC}"
 
+# image specific volatile logfile handlding with MORTSGNA_IMAGE_VOLATILE_LOG_DIR
+require conf/distro/include/mortsgna-image-logfile-volatile.inc
+
 # Yocto tweaks
 require conf/distro/include/mortsgna-core-tweaks.inc

conf/distro/mortsgna.conf

@@ -115,8 +115,9 @@ EXTRA_IMAGE_FEATURES += " \
     allow-empty-password \
     post-install-logging \
 "
-# Ensure postinst.log non volatile
-POSTINST_LOGFILE = "${localstatedir}/postinstall.log"
+
+# default: persistent log
+MORTSGNA_IMAGE_VOLATILE_LOG_DIR ?= "0"
 
 # make x11-base a valid IMAGE_FEATURES
 IMAGE_FEATURES[validitems] += "x11-base"