[type/__uci] Apply all commands in a single batch

cdist/conf/type/__uci/files/uci_apply.sh

@@ -0,0 +1,43 @@
+changes=$(uci changes)
+
+if test -n "${changes}"
+then
+	echo 'Uncommited UCI changes were found on the target:'
+	printf '%s\n\n' "${changes}"
+	echo 'This can be caused by manual changes or due to a previous failed run.'
+	echo 'Please investigate the situation, revert or commit the changes, and try again.'
+	exit 1
+fi >&2
+
+check_errors() {
+	# reads stdin and forwards non-empty lines to stderr.
+	# returns 0 if stdin is empty, else 1.
+	! grep -e . >&2
+}
+
+commit() {
+	uci commit
+}
+
+rollback() {
+	printf '\nAn error occurred when trying to commit UCI transaction!\n' >&2
+
+	uci changes \
+	| sed -e 's/^-//' -e 's/\..*\$//' \
+	| sort -u \
+	| while read -r _package
+	  do
+		  uci revert "${_package}"
+		  echo "${_package}"  # for logging
+	  done \
+	| awk '
+	  BEGIN { printf "Reverted changes in: " }
+	  { printf "%s%s", (FNR > 1 ? ", " : ""), $0 }
+	  END { printf "\n" }' >&2
+
+	return 1
+}
+
+uci_apply() {
+	uci batch 2>&1 | check_errors && commit || rollback
+}

cdist/conf/type/__uci/gencode-remote

@@ -91,3 +91,11 @@ in
 		exit 1
 		;;
 esac
+
+if test -s "${__object:?}/files/uci_batch.txt"
+then
+	cat "${__type:?}/files/uci_apply.sh"
+	printf "uci_apply <<'EOF'\n"
+	cat "${__object:?}/files/uci_batch.txt"
+	printf '\nEOF\n'
+fi