nocloud: add minimal network-config v2 support

lib/tiny-cloud/cloud/nocloud/init

@@ -4,6 +4,12 @@
 
 INIT_ACTIONS_BOOT="$(replace_word set_default_interfaces set_network_interfaces $INIT_ACTIONS_BOOT)"
 
+get_network_config() {
+	IFS="/"
+	yx -f "$TINY_CLOUD_VAR/network-config" $1 2>/dev/null
+	unset IFS
+}
+
 set_resolv_conf() {
 	# resolv.conf
 	local nameservers="$(imds meta-data/resolv_conf/nameservers)"
@@ -43,11 +49,53 @@ want_ephemeral_network() {
 	return 1
 }
 
+set_network_config_v2() {
+	[ -s "$TINY_CLOUD_VAR/network-config" ] || return 1
+	local version="$(get_network_config version)"
+	if [ "$version" != "2" ]; then
+		log -i -t "$phase" warning "$ACTION: unsupported NoCloud network-config version: ${version:-unknown}"
+		return 1
+	fi
+
+	local ethernets="$(get_network_config ethernets)"
+	if [ -z "$ethernets" ]; then
+		log -i -t "$phase" warning "$ACTION: NoCloud network-config v2 has no supported ethernets entries"
+		return 1
+	fi
+
+	printf "%s\n%s\n\n" \
+		"auto lo" \
+		"iface lo inet loopback" \
+		> "$ETC/network/interfaces"
+
+	local iface configured=
+	for iface in $ethernets; do
+		case "$(get_network_config ethernets/$iface/dhcp4)" in
+			true|yes)
+				printf "%s\n%s\n\t%s\n\n" \
+					"auto $iface" \
+					"iface $iface" \
+					"use dhcp" >> "$ETC/network/interfaces"
+				configured=1
+				;;
+		esac
+	done
+
+	if [ -z "$configured" ]; then
+		log -i -t "$phase" warning "$ACTION: NoCloud network-config v2 has no supported ethernets entries"
+		return 1
+	fi
+
+	return 0
+}
+
 init__set_network_interfaces() {
 	local interfaces="$(imds meta-data/network-interfaces)"
 	mkdir -p "$ETC"/network
 	if [ -n "$interfaces" ]; then
 		printf "%s\n" "$interfaces" > "$ETC"/network/interfaces
+	elif set_network_config_v2; then
+		:
 	elif ! [ -f "$ETC"/network/interfaces ]; then
 		init__set_default_interfaces
 	fi

tests/test_env.sh

@@ -36,7 +36,7 @@ fake_umount() {
 		while ! [ -d "\$1" ]; do
 			shift
 		done
-		rm -f "\$1"/meta-data "\$1"/user-data
+		rm -f "\$1"/meta-data "\$1"/user-data "\$1"/network-config
 	EOF
 }
 
@@ -64,6 +64,10 @@ fake_userdata_nocloud() {
 	fake_data_nocloud user-data
 }
 
+fake_network_config_nocloud() {
+	fake_data_nocloud network-config
+}
+
 fake_metadata_aws() {
 	cat > "169.254.169.254.yaml"
 	export WGET_STRIP_PREFIX="/latest/meta-data"

tests/tiny-cloud-alpine.test

@@ -11,6 +11,7 @@ export CLOUD=nocloud
 init_tests \
 	set_ephemeral_network_cmdline \
 	set_network_config_network_interfaces \
+	set_network_config_v2_dhcp4 \
 	set_network_config_auto \
 	userdata_user_name \
 	userdata_user_homedir \
@@ -100,6 +101,26 @@ set_network_config_network_interfaces_body() {
 		cat etc/resolv.conf
 }
 
+set_network_config_v2_dhcp4_body() {
+	fake_network_config_nocloud <<-EOF
+		version: 2
+		ethernets:
+		  eth1:
+		    dhcp4: true
+	EOF
+
+	atf_check \
+		-o match:"rc-update" \
+		-e match:"set_network_interfaces: done" \
+		tiny-cloud boot
+
+	atf_check \
+		-o match:"auto eth1" \
+		-o match:"iface eth1" \
+		-o match:"use dhcp" \
+		cat etc/network/interfaces
+}
+
 set_network_config_auto_body() {
 	fake_metadata_nocloud <<-EOF
 		resolv_conf: