How to run a website for free forever?

This article outline

Cloud hosting
Environment
Application
Traffic
Summary

【How to run a website for free forever?】Apart from the annual fee for domain names, my blog site is running on a cloud server. If there is no accident, the maintenance fee should be zero.
Cloud hostingI use Google Cloud for cloud servers. Google Cloud should be the only cloud server provider that promises to provide Always Free forever. Other cloud service providers should only offer 12-month free usage options to new users.
Of course, the always free option provided by Google Cloud can only be used with a super weak instance:

Computer room in the US
Single shared CPU core
600M of memory
30G storage

The performance may not be as good as a Raspberry Pi, but it is enough for me to run a website.
EnvironmentI used the operating system for convenience: Ubuntu 18.04 LTS
Database
The database uses MySql 8.0 for some reason, but this reports an error directly after apt-get install mysql-server. Looking at /var/log/mysql/error.log, it shows:

2018-08-12T17:55:07.393408Z 0 [System] [MY-013170] [Server] /usr/sbin/mysqld (mysqld 8.0.12) initializing of server has completed 2018-08-12T17:55:11.130992Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.12) starting as process 3112 2018-08-12T17:55:11.782754Z 0 [ERROR] [MY-012681] [InnoDB] InnoDB: mmap(137428992 bytes) failed; errno 12 2018-08-12T17:55:11.782817Z 1 [ERROR] [MY-012956] [InnoDB] InnoDB: Cannot allocate memory for the buffer pool 2018-08-12T17:55:11.782832Z 1 [ERROR] [MY-012930] [InnoDB] InnoDB: Plugin initialization aborted with error Generic error. 2018-08-12T17:55:11.782886Z 1 [ERROR] [MY-010334] [Server] Failed to initialize DD Storage Engine 2018-08-12T17:55:11.784009Z 0 [ERROR] [MY-010020] [Server] Data Dictionary initialization failed. 2018-08-12T17:55:11.784055Z 0 [ERROR] [MY-010119] [Server] Aborting 2018-08-12T17:55:11.789921Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.12)MySQL Community Server - GPL. 2018-08-12T17:56:06.388162Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.12) starting as process 3276 2018-08-12T17:56:07.253414Z 0 [ERROR] [MY-012681] [InnoDB] InnoDB: mmap(137428992 bytes) failed; errno 12 2018-08-12T17:56:07.253518Z 1 [ERROR] [MY-012956] [InnoDB] InnoDB: Cannot allocate memory for the buffer pool 2018-08-12T17:56:07.253535Z 1 [ERROR] [MY-012930] [InnoDB] InnoDB: Plugin initialization aborted with error Generic error. 2018-08-12T17:56:07.253564Z 1 [ERROR] [MY-010334] [Server] Failed to initialize DD Storage Engine 2018-08-12T17:56:07.255109Z 0 [ERROR] [MY-010020] [Server] Data Dictionary initialization failed. 2018-08-12T17:56:07.255993Z 0 [ERROR] [MY-010119] [Server] Aborting 2018-08-12T17:56:07.320087Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.12)MySQL Community Server - GPL.

Direct memory is insufficient, mysqld cannot start.
I had to modify the /etc/mysql/mysql.conf.d/mysqld.cnf file, adding at the end:

performance_schema = off

One line, disable performance_schema to save memory usage, mysql can start normally.
nginx
Of course, nginx is also needed, just apt-get install nginx.
ApplicationI used Go to write the entire website Application, and used gorazor, esc and other tools to package the used templates and static resource files into executable files.
The entire program occupies less than 20M of memory when running, and there are more than one hundred trillion of free memory:

$ cat /proc/16537/status Name:goblog Umask:0002 State:S (sleeping) Tgid:16537 Ngid:0 Pid:16537 PPid:16403 TracerPid:0 Uid:1001100110011001 Gid:1002100210021002 FDSize: 256 Groups: 4 20 24 25 29 30 44 46 108 114 1000 1001 1002 NStgid: 16537 NSpid:16537 NSpgid: 16537 NSsid:16403 VmPeak:16820 kB VmSize:16820 kB VmLck:0 kB VmPin:0 kB VmHWM:13356 kB VmRSS:9564 kB RssAnon:5720 kB RssFile:3844 kB RssShmem:0 kB VmData:8920 kB VmStk:132 kB VmExe:4320 kB VmLib:8 kB VmPTE:80 kB VmSwap:0 kB$ free -h totalusedfreesharedbuff/cacheavailable Mem:581M352M66M900K162M135M Swap:0B0B0B

TrafficThe free instance of Google Cloud Service does not charge money when running, but the traffic generated by the instance running website may require money. For example, the access traffic generated from China and Australia is not free.
How to do?
Set a cloudflare CDN directly in front of the website. Cloudflare provides a free CDN for personal sites!
If cloudflare goes back to Google Cloud, it is obviously impossible to take traffic from China and Australia.
SummaryIn this way, we can run a website quietly and almost permanently for free.