diff --git a/check_process b/check_process
index 2b13920..89023cf 100644
--- a/check_process
+++ b/check_process
@@ -23,9 +23,9 @@
 			setup_private=1
 			setup_public=1
 			upgrade=1
-			upgrade=1	from_commit=CommitHash
+			;upgrade=1	from_commit=CommitHash
 			backup_restore=1
-			multi_instance=1
+			multi_instance=0
 			# This test is no longer necessary since the version 2.7 (PR: https://github.com/YunoHost/yunohost/pull/304), you can still do it if your app could be installed with this version.
 			# incorrect_path=1
 			port_already_use=0
diff --git a/scripts/_common.sh b/scripts/_common.sh
index 38aa8ed..f55d066 100644
--- a/scripts/_common.sh
+++ b/scripts/_common.sh
@@ -17,6 +17,21 @@ pkg_dependencies="g++"
 # EXPERIMENTAL HELPERS
 #=================================================
 
+#!/bin/bash
+
+# Execute a command as another user
+# usage: exec_as USER COMMAND [ARG ...]
+exec_as() {
+  local USER=$1
+  shift 1
+
+  if [[ $USER = $(whoami) ]]; then
+    eval "$@"
+  else
+    sudo PATH=$PATH -u "$USER" "$@"
+  fi
+}
+
 #=================================================
 # FUTURE OFFICIAL HELPERS
 #=================================================
diff --git a/scripts/install b/scripts/install
index 25da065..01599c3 100644
--- a/scripts/install
+++ b/scripts/install
@@ -142,7 +142,7 @@ ynh_add_nginx_config
 ynh_script_progression --message="Configuring system user..." --time --weight=1
 
 # Create a system user
-ynh_system_user_create --username=$app
+ynh_system_user_create $app $final_path
 
 #=================================================
 # SPECIFIC SETUP
@@ -151,10 +151,12 @@ ynh_system_user_create --username=$app
 #=================================================
 ynh_script_progression --message="Performing Node app installation..." --time --weight=1
 
+chown -R $app: $final_path
+
 pushd $final_path/src
-	ynh_debug_exec $nodejs_path/npm install node-gyp
-	ynh_debug_exec $nodejs_path/npm install
-	ynh_debug_exec $nodejs_path/npm audit fix
+	exec_as $app $nodejs_path/npm install node-gyp
+	exec_as $app $nodejs_path/npm install
+	exec_as $app $nodejs_path/npm audit fix
 popd
 
 #=================================================
@@ -202,9 +204,9 @@ ynh_script_progression --message="Configuring a systemd service..." --time --wei
 
 # Create a dedicated systemd config
 ynh_add_systemd_config
-ynh_replace_string "__ENV_PATH__" "$PATH" "/etc/systemd/system/$app.service"
-ynh_replace_string "__NODEJS_PATH__" "/opt/node_n/n/versions/node/$nodejs_version/bin/" "/etc/systemd/system/$app.service"
-ynh_replace_string "__FINALPATH__" "$final_path" "/etc/systemd/system/$app.service"
+ynh_replace_string "__ENV_PATH__" "$PATH" "$finalsystemdconf"
+ynh_replace_string "__NODEJS_PATH__" "$nodejs_path" "$finalsystemdconf"
+ynh_replace_string "__FINALPATH__" "$final_path" "$finalsystemdconf"
 
 systemctl daemon-reload
 
diff --git a/scripts/remove b/scripts/remove
index c057776..9cf7ddf 100644
--- a/scripts/remove
+++ b/scripts/remove
@@ -33,6 +33,14 @@ then
 	yunohost service remove $app
 fi
 
+#=================================================
+# STOP AND REMOVE SERVICE
+#=================================================
+ynh_script_progression --message="Stopping and removing the systemd service..." --time --weight=1
+
+# Remove the dedicated systemd config
+ynh_remove_systemd_config
+
 #=================================================
 # REMOVE DEPENDENCIES
 #=================================================
diff --git a/scripts/upgrade b/scripts/upgrade
index 1957c55..c9b9c15 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -20,6 +20,7 @@ domain=$(ynh_app_setting_get --app=$app --key=domain)
 path_url=$(ynh_app_setting_get --app=$app --key=path)
 is_public=$(ynh_app_setting_get --app=$app --key=is_public)
 final_path=$(ynh_app_setting_get --app=$app --key=final_path)
+port=$(ynh_app_setting_get --app=$app --key=port)
 
 #=================================================
 # CHECK VERSION
@@ -119,7 +120,10 @@ ynh_add_nginx_config
 #=================================================
 ynh_script_progression --message="Upgrading dependencies..." --time --weight=1
 
-#ynh_install_app_dependencies $pkg_dependencies
+ynh_install_app_dependencies $pkg_dependencies
+
+ynh_install_nodejs --nodejs_version=$nodejs_version
+ynh_use_nodejs
 
 #=================================================
 # CREATE DEDICATED USER
@@ -127,7 +131,7 @@ ynh_script_progression --message="Upgrading dependencies..." --time --weight=1
 ynh_script_progression --message="Making sure dedicated system user exists..." --time --weight=1
 
 # Create a dedicated user (if not existing)
-ynh_system_user_create --username=$app
+ynh_system_user_create $app $final_path
 
 #=================================================
 # SPECIFIC UPGRADE
@@ -136,8 +140,39 @@ ynh_system_user_create --username=$app
 #=================================================
 ynh_script_progression --message="Performing Node app installation..." --time --weight=1
 
+chown -R $app: $final_path
+
 pushd $final_path/src
-	npm install
+	exec_as $app $nodejs_path/npm install node-gyp
+	exec_as $app $nodejs_path/npm install
+	exec_as $app $nodejs_path/npm audit fix
+popd
+
+#=================================================
+# MODIFY A CONFIG FILE
+#=================================================
+
+# Setup env file
+mkdir -p $final_path
+env_file=$final_path/src/.env
+touch $env_file
+chmod 600 $env_file
+
+echo "ZT_TOKEN=$(</var/lib/zerotier-one/authtoken.secret)" >> $env_file
+echo "ZT_ADDR=localhost:$(</var/lib/zerotier-one/zerotier-one.port)" >> $env_file
+echo "HTTP_PORT=$port" >> $env_file
+
+cp $final_path/src/etc/default.passwd $final_path/src/etc/passwd
+
+#=================================================
+# LINK CERTIFICATES
+#=================================================
+
+# Even though one can stay in HTTP mode, the ztncui requires SSL certificates
+# let's use the ones of the domain
+pushd $final_path/src/etc/tls
+	cp /etc/yunohost/certs/$domain/key.pem privkey.pem
+	cp /etc/yunohost/certs/$domain/crt.pem fullchain.pem
 popd
 
 #=================================================
@@ -155,6 +190,11 @@ ynh_script_progression --message="Upgrading systemd configuration..." --time --w
 
 # Create a dedicated systemd config
 ynh_add_systemd_config
+ynh_replace_string "__ENV_PATH__" "$PATH" "$finalsystemdconf"
+ynh_replace_string "__NODEJS_PATH__" "$nodejs_path" "$finalsystemdconf"
+ynh_replace_string "__FINALPATH__" "$final_path" "$finalsystemdconf"
+
+systemctl daemon-reload
 
 #=================================================
 # GENERIC FINALIZATION
@@ -163,7 +203,7 @@ ynh_add_systemd_config
 #=================================================
 
 # Set permissions on app files
-chown -R root: $final_path
+chown -R $app: $final_path
 
 #=================================================
 # SETUP SSOWAT