Tools: improved error handling for unitc

This patch does a number of things to help when failing to apply a new
configuration.

* The error body from the Unit control API is displayed which can have
  useful troubleshooting information (when the version of curl supports it).

* When using the EDIT option, the temporary file with unapplied changes is
  preserved so that the user can edit it again without losing their work.

* Editing JavaScript modules no longer requires that module to have been
  enabled.

* Failure to apply edited JavaScript modules now rolls-back to the previous
  configuration instead of deleting the module.

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

1 files changed, 52 insertions, 24 deletions

diff --git a/tools/unitc b/tools/unitc
index 9fba4c6d..332b2311 100755
--- a/tools/unitc
+++ b/tools/unitc
@@ -249,41 +249,58 @@ else
 	NOLOG=1
 fi
 
+# Set the base curl command after testing for newer features
+#
+$RPC_CMD curl --fail-with-body --version > /dev/null
+if [ $? -eq 0 ]; then
+	CURL_CMD="$RPC_CMD curl --silent --fail-with-body"
+else
+	CURL_CMD="$RPC_CMD curl --silent --fail"
+fi
+
 # Adjust HTTP method and curl params based on presence of stdin payload
 #
 if [ -t 0 ] && [ ${#CONF_FILES[@]} -eq 0 ]; then
 	if [ "$METHOD" = "DELETE" ]; then
-		$RPC_CMD curl -X $METHOD $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
+		$CURL_CMD -X $METHOD $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
 	elif [ "$METHOD" = "EDIT" ]; then
 		EDITOR=$(test "$EDITOR" && printf '%s' "$EDITOR" || command -v editor || command -v vim || echo vi)
 		EDIT_FILENAME=/tmp/${0##*/}.$$${URI//\//_}
-		$RPC_CMD curl -fsS $UNIT_CTRL$URI > $EDIT_FILENAME || exit 2
+		$CURL_CMD -S $UNIT_CTRL$URI > $EDIT_FILENAME || exit 2
 		if [ "${URI:0:12}" = "/js_modules/" ]; then
 			if ! hash jq 2> /dev/null; then
 				echo "${0##*/}: ERROR: jq(1) is required to edit JavaScript modules; install at <https://stedolan.github.io/jq/>"
 				exit 1
 			fi
 			jq -r < $EDIT_FILENAME > $EDIT_FILENAME.js # Unescape linebreaks for a better editing experience
+			cp $EDIT_FILENAME.js /tmp/${0##*/}.$$bak
 			EDIT_FILE=$EDIT_FILENAME.js
 			$EDITOR $EDIT_FILENAME.js || exit 2
-			# Remove the references, delete old config, push new config+reference
-			$RPC_CMD curl -fsS $UNIT_CTRL/config/settings/js_module > /tmp/${0##*/}.$$_js_module && \
-			$RPC_CMD curl -X DELETE $UNIT_CTRL/config/settings/js_module && \
-			$RPC_CMD curl -fsSX DELETE $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ && \
-			printf "%s" "$(< $EDIT_FILENAME.js)" | $RPC_CMD curl -fX PUT --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ && \
-			cat /tmp/${0##*/}.$$_js_module | $RPC_CMD curl -X PUT --data-binary @- $UNIT_CTRL/config/settings/js_module 2> /tmp/${0##*/}.$$
+			# Test if this module is enabled
+			$CURL_CMD $UNIT_CTRL/config/settings/js_module > /tmp/${0##*/}.$$_js_module
+			if [ $? -eq 0 ]; then
+				# Remove the references, delete old module, push new module+reference
+				$CURL_CMD -X DELETE $UNIT_CTRL/config/settings/js_module && \
+				$CURL_CMD -X DELETE $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ && \
+				printf "%s" "$(< $EDIT_FILENAME.js)" | $CURL_CMD -X PUT --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ && \
+				cat /tmp/${0##*/}.$$_js_module | $CURL_CMD -X PUT --data-binary @- $UNIT_CTRL/config/settings/js_module 2> /tmp/${0##*/}.$$
+			else
+				# Delete then re-apply the module
+				$CURL_CMD -X DELETE $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ && \
+				printf "%s" "$(< $EDIT_FILENAME.js)" | $CURL_CMD -X PUT --data-binary @- $UNIT_CTRL$URI 2>&1 2> /tmp/${0##*/}.$$
+			fi
 		elif [ $CONVERT -eq 1 ]; then
 			$CONVERT_FROM_JSON < $EDIT_FILENAME > $EDIT_FILENAME.yaml
 			$EDITOR $EDIT_FILENAME.yaml || exit 2
-			$CONVERT_TO_JSON < $EDIT_FILENAME.yaml | $RPC_CMD curl -X PUT --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
+			$CONVERT_TO_JSON < $EDIT_FILENAME.yaml | $CURL_CMD -X PUT --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
 		else
 			tr -d '\r' < $EDIT_FILENAME > $EDIT_FILENAME.json # Remove carriage-return from newlines
 			$EDITOR $EDIT_FILENAME.json || exit 2
-			cat $EDIT_FILENAME.json | $RPC_CMD curl -X PUT --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
+			cat $EDIT_FILENAME.json | $CURL_CMD -X PUT --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
 		fi
 	else
 		SHOW_LOG=$(echo $URI | grep -c ^/control/)
-		$RPC_CMD curl $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
+		$CURL_CMD $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
 	fi
 else
 	if [ "$METHOD" = "INSERT" ]; then
@@ -293,9 +310,9 @@ else
 		fi
 		NEW_ELEMENT=$(cat ${CONF_FILES[@]})
 		echo $NEW_ELEMENT | jq > /dev/null || exit $? # Test the input is valid JSON before proceeding
-		OLD_ARRAY=$($RPC_CMD curl -s $UNIT_CTRL$URI)
+		OLD_ARRAY=$($CURL_CMD -s $UNIT_CTRL$URI)
 		if [ "$(echo $OLD_ARRAY | jq -r type)" = "array" ]; then
-			echo $OLD_ARRAY | jq ". |= [$NEW_ELEMENT] + ." | $RPC_CMD curl -X PUT --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
+			echo $OLD_ARRAY | jq ". |= [$NEW_ELEMENT] + ." | $CURL_CMD -X PUT --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
 		else
 			echo "${0##*/}: ERROR: the INSERT method expects an array"
 			exit 3
@@ -305,12 +322,31 @@ else
 			cat ${CONF_FILES[@]} | $CONVERT_TO_JSON > /tmp/${0##*/}.$$_json
 			CONF_FILES=(/tmp/${0##*/}.$$_json)
 		fi
-		cat ${CONF_FILES[@]} | $RPC_CMD curl -X $METHOD --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
+		cat ${CONF_FILES[@]} | $CURL_CMD -X $METHOD --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
 	fi
 fi
 
-CURL_STATUS=${PIPESTATUS[0]}
-if [ $CURL_STATUS -ne 0 ]; then
+CURL_STATUS=${PIPESTATUS[1]}
+if [ $CURL_STATUS -eq 0 ]; then
+	rm -f /tmp/${0##*/}.$$* 2> /dev/null
+	if [ $SHOW_LOG -gt 0 ] && [ $NOLOG -eq 0 ] && [ $QUIET -eq 0 ]; then
+		echo -n "${0##*/}: Waiting for log..."
+		sleep $SHOW_LOG
+		echo ""
+		sed -n $((LOG_LEN+1)),\$p $ERROR_LOG
+	fi
+elif [ $CURL_STATUS -eq 22 ]; then
+	echo "${0##*/}: ERROR: configuration not applied"
+	if [ "$METHOD" = "EDIT" ]; then
+		if [ -f /tmp/${0##*/}.$$_js_module ]; then
+			echo "${0##*/}: NOTICE: restoring previous configuration"
+			printf "%s" "$(< /tmp/${0##*/}.$$bak)" | $CURL_CMD -X PUT --data-binary @- $UNIT_CTRL$URI && \
+			cat /tmp/${0##*/}.$$_js_module | $CURL_CMD -X PUT --data-binary @- $UNIT_CTRL/config/settings/js_module 2> /tmp/${0##*/}.$$
+		fi
+		echo "${0##*/}: NOTICE: $(ls $EDIT_FILENAME.*) contains unapplied edits"
+		rm /tmp/${0##*/}.$$ $EDIT_FILENAME
+	fi
+else
 	echo "${0##*/}: ERROR: curl(1) exited with an error ($CURL_STATUS)"
 	if [ $CURL_STATUS -eq 7 ] && [ $REMOTE -eq 0 ]; then
 		echo "${0##*/}: Check that you have permission to access the Unit control socket, or try again with sudo(8)"
@@ -320,11 +356,3 @@ if [ $CURL_STATUS -ne 0 ]; then
 	fi
 	exit 4
 fi
-rm -f /tmp/${0##*/}.$$* 2> /dev/null
-
-if [ $SHOW_LOG -gt 0 ] && [ $NOLOG -eq 0 ] && [ $QUIET -eq 0 ]; then
-	echo -n "${0##*/}: Waiting for log..."
-	sleep $SHOW_LOG
-	echo ""
-	sed -n $((LOG_LEN+1)),\$p $ERROR_LOG
-fi