Add configuration management

README.md

@@ -104,6 +104,32 @@ Tests on one orange pi zero show that the time from power on until a login
 prompt on the serial console is about 1 minute.
 
 
+Applying persistent configurations
+----------------------------------
+
+Custom configurations are saved as tar.gz archives in conf.d at the root of the
+fat16 file system. After the start of userspace and before systemd is launched,
+content in each archive is extracted in alphabetical order to /etc of the ramdisk,
+so files in an archive towards the end of the list overwrite those from an earlier
+archive in case of a filename conflict, and systemd will only see the final
+(highest priority) configurations. For example:
+
+    /conf.d/00-tomesh-base.tar.gz
+            10-tomesh-wlan-mesh-top-gs07-rt5572.tar.gz
+            11-tomesh-wlan-hostap-tplink-tl-wn722n.tar.gz
+            50-node-config-save.tar.gz
+            90-user-custom-configs.tar.gz
+
+This allows local mesh communities to customize nodes by distributing archives
+of systemd.network configuration files, or any files that are to be read from
+/etc. The user simply mounts the fat filesystem like a USB key and drops tar.gz
+files into conf.d and backs them up across software updates.
+
+If the node needs to save persistent configurations while running, such as
+remembering a MAC address, it can save the current /etc directory into a
+50-node-config-save.tar.gz archive by running `config_save`. The user may
+also manually add configurations with higher priority archive names.
+
 Test the Debian image using Qemu
 --------------------------------
 

debian/packages.d/README

@@ -14,7 +14,7 @@ customisations.  These customisations are applied in several phases,
 and each package that is found installed in the rescue system will
 attempt to run its matching script during each phase.
 
-Curently the phases are:
+Currently the phases are:
 
 "minimise"
     During this phase, anything that can be removed to minimise the

debian/packages.d/systemd.customise.add/init.d/20confd.sh

@@ -0,0 +1,39 @@
+# Apply configurations from conf.d
+#
+# Copyright (C) 2018 Benedict Lau <[email protected]>
+
+CONFDIR=conf.d
+
+try_partition() {
+    # Create file system node from partition
+    #mknod /dev/$1 b $2 $3 2>/dev/null
+
+    # Mount partition as read-only
+    mount /dev/$1 /mnt -o ro
+
+    # Find conf.d in root of partition and extract in alphabetical order each
+    # tar.gz archive into the ramdisk /etc, overwriting any existing file
+    if [ -d "/mnt/$CONFDIR" ]; then
+        confs=$(find /mnt/$CONFDIR -name *.tar.gz)
+        for conf in $confs; do
+            echo Applying configurations from /dev/$1: $conf
+            tar --extract --gzip -f $conf -C /etc
+        done
+    fi
+
+    # Unmount partition
+    umount /mnt
+}
+
+# Mount proc if not already mounted
+#mount -t proc proc /proc
+
+cat /proc/partitions | while read major minor size name; do
+    # Check each partition matching sd*[0-9] (e.g. sda1) or mmcblk*p* (e.g. mmcblk0p1)
+    case $name in
+        sd*[0-9]|mmcblk*p*)
+            echo Checking for configuration files on $name
+            try_partition $name $major $minor
+            ;;
+    esac
+done

debian/scripts/usr/local/bin/config_save

@@ -0,0 +1,35 @@
+# Save current configurations to partition containing conf.d
+#
+# Copyright (C) 2018 Benedict Lau <[email protected]>
+
+CONFDIR=conf.d
+
+try_partition() {
+    # Create file system node from partition
+    #mknod /dev/$1 b $2 $3 2>/dev/null
+
+    # Mount partition as read-write
+    mount /dev/$1 /mnt
+
+    # Find conf.d in root of partition and save current configurations in /etc
+    if [ -d "/mnt/$CONFDIR" ]; then
+        echo Saving configurations to /dev/$1: "/mnt/$CONFDIR/50-node-config-save.tar.gz"
+        tar --create --gzip -f 50-node-config-save.tar.gz -C /etc .
+    fi
+
+    # Unmount partition
+    umount /mnt
+}
+
+# Mount proc if not already mounted
+#mount -t proc proc /proc
+
+cat /proc/partitions | while read major minor size name; do
+    # Check each partition matching sd*[0-9] (e.g. sda1) or mmcblk*p* (e.g. mmcblk0p1)
+    case $name in
+        sd*[0-9]|mmcblk*p*)
+            echo Checking for configuration directory on $name
+            try_partition $name $major $minor
+            ;;
+    esac
+done