Added proxysql system user and group management

During the make install phase a proxysql system user and group are created automatically.
As system user this cannot be used for login to the system but just to run the program.

During the make uninstall phase the proxysql user and group are deleted automatically.

Fixed the error with the number of endif statements that prevented the execution of the uninstall rule.

Makefile

@@ -19,6 +19,8 @@ ifeq ($(wildcard /usr/lib/systemd/system), /usr/lib/systemd/system)
 else
 	SYSTEMD=0
 endif
+USERCHECK := $(shell getent passwd proxysql)
+GROUPCHECK := $(shell getent group proxysql)
 
 .PHONY: default
 default: build_deps build_lib build_src
@@ -346,10 +348,15 @@ cleanbuild:
 	cd lib && ${MAKE} clean
 	cd src && ${MAKE} clean
 
+.PHONY: install
 install: src/proxysql
 	install -m 0755 src/proxysql /usr/bin
 	install -m 0600 etc/proxysql.cnf /etc
 	if [ ! -d /var/lib/proxysql ]; then mkdir /var/lib/proxysql ; fi
+ifeq ($(findstring proxysql,$(USERCHECK)),)
+	@echo "Creating proxysql user and group"
+	useradd -r -U -s /bin/false proxysql
+endif
 ifeq ($(SYSTEMD), 1)
 	install -m 0644 systemd/system/proxysql.service /usr/lib/systemd/system/
 	systemctl enable proxysql.service
@@ -370,35 +377,44 @@ endif
 endif
 endif
 endif
-.PHONY: install
+endif
 
+.PHONY: uninstall
 uninstall:
-	rm /etc/proxysql.cnf
-	rm /usr/bin/proxysql
-	rmdir /var/lib/proxysql 2>/dev/null || true
+	if [ -f /etc/proxysql.cnf ]; then rm /etc/proxysql.cnf ; fi
+	if [ -f /usr/bin/proxysql ]; then rm /usr/bin/proxysql ; fi
+	if [ -d /var/lib/proxysql ]; then rmdir /var/lib/proxysql 2>/dev/null || true ; fi
 ifeq ($(SYSTEMD), 1)
 		systemctl stop proxysql.service
-		rm /usr/lib/systemd/system/proxysql.service
+		if [ -f /usr/lib/systemd/system/proxysql.service ]; then rm /usr/lib/systemd/system/proxysql.service ; fi
+		find /etc/systemd -name "proxysql.service" -exec rm {} \;
+		systemctl daemon-reload
 else
 ifeq ($(DISTRO),"CentOS Linux")
 		chkconfig --level 0123456 proxysql off
-		rm /etc/init.d/proxysql
+		if [ -f /etc/init.d/proxysql ]; then rm /etc/init.d/proxysql ; fi
 else
 ifeq ($(DISTRO),"Red Hat Enterprise Linux Server")
 		chkconfig --level 0123456 proxysql off
-		rm /etc/init.d/proxysql
+		if [ -f /etc/init.d/proxysql ]; then rm /etc/init.d/proxysql ; fi
 else
 ifeq ($(DISTRO),"Ubuntu")
-		rm /etc/init.d/proxysql
+		if [ -f /etc/init.d/proxysql ]; then rm /etc/init.d/proxysql ; fi
 		update-rc.d proxysql remove
 else
 ifeq ($(DISTRO),"Debian GNU/Linux")
-		rm /etc/init.d/proxysql
+		if [ -f /etc/init.d/proxysql ]; then rm /etc/init.d/proxysql ; fi
 		update-rc.d proxysql remove
 endif
 endif
 endif
 endif
 endif
+ifneq ($(findstring proxysql,$(USERCHECK)),)
+	@echo "Deleting proxysql user"
+	userdel proxysql
+endif
+ifneq ($(findstring proxysql,$(GROUPCHECK)),)
+	@echo "Deleting proxysql group"
+	groupdel proxysql
 endif
-.PHONY: uninstall