mdev hotplug

* basic framework
* nvme-ebs-links module
* tiny-cloud-early installs hotplug modules

etc/conf.d/tiny-cloud

@@ -1,7 +1,8 @@
 # Tiny Cloud configuration
 
 # REQUIRED: The instance's cloud provider (valid: aws, azure, gcp, oci)
-CLOUD=
+# valid: aws, azure, gcp, oci
+#CLOUD=
 
 # User account where instance SSH keys are installed
 #CLOUD_USER=alpine
@@ -20,3 +21,10 @@ CLOUD=
 
 # Location of log directory
 #TINY_CLOUD_LOGS=/var/log
+
+# Hotplug Method (valid: mdev)
+#HOTPLUG_TYPE=mdev
+
+# Cloud-related Hotplug Modules
+# valid: vnic_eth_hotplug, nvme_ebs_links (aws)
+#HOTPLUG_MODULES=

etc/init.d/tiny-cloud-early

@@ -16,5 +16,9 @@ start() {
 	expand_root
 	eend $?
 
-	# TODO: _setup mdev things, if applicable
+	if has_cloud_hotplugs; then
+		ebegin "Installing Cloud Hotplugs"
+		install_hotplugs
+		eend $?
+	fi
 }

lib/mdev/nvme-ebs-links

@@ -0,0 +1,48 @@
+#!/bin/sh
+# vim:set ts=2 et:
+
+# nvme tool not installed?
+[ -x /usr/sbin/nvme ] || exit
+
+PROC="$(basename "$0")[$$]"
+
+log() {
+  FACILITY="kern.$1"
+  shift
+  logger -p "$FACILITY" -t "$PROC" "$@"
+}
+
+raw_ebs_alias() {
+  /usr/sbin/nvme id-ctrl "/dev/$BASE" -b 2>/dev/null | dd bs=32 skip=96 count=1 2>/dev/null
+}
+
+case $ACTION in
+  add|"")
+    BASE=$(echo "$MDEV" | sed -re 's/^(nvme[0-9]+n[0-9]+).*/\1/')
+    PART=$(echo "$MDEV" | sed -re 's/nvme[0-9]+n[0-9]+p?//g')
+    MAXTRY=30
+    TRY=0
+    until [ -n "$EBS" ]; do
+      EBS=$(raw_ebs_alias | sed -nre '/^(\/dev\/)?(s|xv)d[a-z]{1,2} /p' | tr -d ' ')
+      [ -n "$EBS" ] && break
+      TRY=$((TRY + 1))
+      if [ $TRY -eq $MAXTRY ]; then
+        log err "Failed to get EBS volume alias for $MDEV after $MAXTRY attempts ($(raw_ebs_alias))"
+        exit 1
+      fi
+      sleep 0.1
+    done
+    # remove any leading '/dev/', 'sd', or 'xvd', and append partition
+    EBS=${EBS#/dev/}
+    EBS=${EBS#sd}
+    EBS=${EBS#xvd}$PART
+    ln -sf "$MDEV" "sd$EBS" && log notice "Added sd$EBS symlink for $MDEV"
+    ln -sf "$MDEV" "xvd$EBS" && log notice "Added xvd$EBS symlink for $MDEV"
+    ;;
+  remove)
+    for TARGET in sd* xvd*
+    do
+      [ "$(readlink "$TARGET" 2>/dev/null)" = "$MDEV" ] && rm -f "$TARGET" && log notice "Removed $TARGET symlink for $MDEV"
+    done
+    ;;
+esac

lib/tiny-cloud/aws/mdev

@@ -0,0 +1,11 @@
+# AWS mdev Hotplug Modules
+# vim:set ft=sh ts=4 noet:
+
+# makes symlinks for NVMe devices that correlate to AWS EBS sd/xvd devices
+mod__nvme_ebs_links() {
+	# nvme-cli not installed?
+	[ -x /usr/sbin/nvme ] || return 1
+
+	install_before '^nvme\.\*' \
+		'nvme[0-9]+n.*	root:disk 0660 */lib/mdev/nvme-ebs-links'
+}

lib/tiny-cloud/init-early

@@ -17,10 +17,29 @@ expand_root() {
 	)
 
 	if [ "$mountpoint" != "$volume" ]; then
-		partition=$(echo "$mountpoint" | sed -Ee "s/.*(\d+)$/\1/")
+		# it's a partition, resize it
+		local partition=$(echo "$mountpoint" | sed -Ee "s/.*(\d+)$/\1/")
 		echo ", +" | sfdisk -q --no-reread -N "$partition" "$volume"
 		partx -u "$volume"
 	fi
+	# resize filesystem
 	mount -orw,remount /
 	resize2fs "$mountpoint"
-}
+}
+
+has_cloud_hotplugs() { [ -n "$HOTPLUG_MODULES" ]; }
+
+install_hotplugs() {
+	for module in $HOTPLUG_MODULES; do
+		local result='-'
+
+		echo -n " $module"
+		if type "mod__$module" | grep -q "is a function"; then
+			"mod__$module" && result='+' || result='!'
+		fi
+		echo -n "($result)"
+	done
+}
+
+HOTPLUG_TYPE=${HOTPLUG_TYPE:-mdev}
+source "$TINY_CLOUD_LIBS/$HOTPLUG_TYPE"

lib/tiny-cloud/mdev

@@ -0,0 +1,32 @@
+# Tiny Cloud - mdev hotplug functions
+# vim:set ft=sh ts=4 noet:
+
+# generic helper function to install mdev rules
+install_before() {
+	local before="$1"
+	shift
+	local line="$*"
+
+	# already installed
+	fgrep -q "$line" /etc/mdev.conf && return 0
+
+	if grep -q "$before" /etc/mdev.conf; then
+		# install before existing rule
+		line="-$line"
+	else
+		# no rule exists, put it before the catch-all fallback
+		before='^# fallback'
+	fi
+	sed -i -Ee "s|($before.*)|$line\n\1|" /etc/mdev.conf
+}
+
+# hotpluggable VNICs (multi-cloud)
+mod__vnic_eth_hotplug() {
+	# TODO: missing dependencies?  return 1
+	install_before '^eth' \
+		'eth[0-9]*		root:root 0644 */lib/mdev/vnic-eth-hotplug'
+}
+
+# load cloud-specific functions
+
+[ -f "$TINY_CLOUD_LIBS/$CLOUD/mdev" ] && source "$TINY_CLOUD_LIBS/$CLOUD/mdev"