[chores] Minor improvements

openwisp-monitoring/files/monitoring.agent

@@ -118,7 +118,7 @@ handle_sigusr1() {
 }
 
 send_data() {
-	success_count=1
+	success=1
 	while true; do
 		for file in "$TMP_DIR"/*; do
 			if [ ! -f "$file" ]; then
@@ -167,7 +167,7 @@ send_data() {
 				# send data
 				response_code=$($CURL_COMMAND -H "Content-Type: application/json" -d "$data" "$url")
 				if [ "$response_code" = "200" ]; then
-					success_count=$((success_count + 1))
+					success=$((success + 1))
 					if [ "$VERBOSE_MODE" -eq "1" ]; then
 						logger -s "Data sent successfully." \
 							-p daemon.info
@@ -192,13 +192,28 @@ send_data() {
 					[ "$VERBOSE_MODE" -eq "1" ] && logger -s "Data not sent successfully. Retrying in $timeout seconds." \
 						-p daemon.warn
 					failures=$((failures + 1))
+					if [ "$response_code" = "404" ]; then
+						# If we get a HTTP 404 response, it could mean that the device has been deleted from OpenWISP
+						# Controller. We check if openwisp-config agent is running to determine if the device has been
+						# deleted. If openwisp-config agent is not running, the monitoring agent will also exit.
+						if ! pgrep -x "openwisp_config" >/dev/null; then
+							logger -s "Giving up and shutting down: the device may have been deleted from OpenWISP Controller" \
+								-t openwisp-monitoring \
+								-p daemon.err
+							# get process id of the process collecting data
+							pid=$(pgrep -f "openwisp-monitoring.*--mode collect")
+							kill -SIGKILL "$pid"
+							exit 2
+						fi
+					fi
 					sleep "$timeout"
 				fi
 			done
 			# retry sending same data again in next cycle
 			[ "$failures" -eq "$MAX_RETRIES" ] && break
-			# pause for a while after every 10 successful request sent
-			if [ $((success_count % 10)) -eq 0 ]; then
+			# pause for a random time between 1 and 5 seconds every
+			# 10 successful requests sent to avoid overload the server
+			if [ $((success % 10)) -eq 0 ]; then
 				pause_duration=$(/usr/sbin/openwisp-get-random-number 1 5)
 				sleep "$pause_duration"
 			fi