Which web server monitoring system to choose?

Question

linux

Good afternoon. Please advise a free monitoring system for a web server (Ubuntu Server + nginx + php-fpm + mysql) with php sites on board. The network is full of materials ala "50 monitoring tools". There is no time to try each.
Requirements:
1. Means of tracking problems in system performance (for a person who does not have the opportunity to delve into the intricacies of system administration).
2. Notification by e-mail about critical problems on the server.
3. The preferred format is a third-party web service, but I will also consider software options with easy installation on Ubuntu Server, but again with a GUI.
4. Easy installation and configuration.
5. Availability of a free plan.
6. Convenient access from Ubuntu and Android whenever possible
It's probably too bold for free software. But anyway. Suggest options. Thank you.
An important addition: there is no Apache on the server and its installation is not planned.

Answer 1

It's easier to advise what not to join - zabbix, nagios. Everything is complicated, extremely monstrous and vyrviglazno.
Better something newer, easier . And prettier

Answer 2

It's easier monit didn't see anything
but build graphs - munin

Answer 3

And what will pictures in monitoring give to a person who "does not have the opportunity to delve into the intricacies of system administration"? It is not enough to see the data, they must be correctly interpreted, and for this it is necessary to understand what they mean and what should or should not be done in various situations.
Those. you probably don’t need anything more than monitoring the availability of a site ... For this, you can take any external service, even starting with Yandex metrics.
But if you want charts, then the simplest free monitoring with installation at your place is probably munin. For a single server, with minimal installation and configuration effort, this is probably the best option. Especially if you just let him build graphs on the crown, and not bother with the cgi mode.

Answer 4

Netdata
You can teach it to send notifications.