I hope that I can get some advice from more knowledgeable admins regarding my software upgrading plan.

I'm getting the following messages from my Admin CP:

Quote

You are running PHP version 5.6.36-0+deb8u1. While this version is compatible, future releases of our software will require version 7.0.0 or above.

 

Quote

You are running MySQL version 5.5.60-0+deb8u1-log. While this version is compatible, future releases of our software will require version 5.6.2 or above.

My VPS is running Debian 8.11... As far as I know, it doesn't offer any native way to upgrade both MySQL and php.

My plan is the following, just in order to simplify things as much as possible:

1. Install Maria DB and use it instead of MySQL, because that's what Debian 9 supports natively.

2. Upgrade to Debian 9 altogether, since it also supports php-7.

3. Install php-7.

I'm not sure though what exactly will have to be changed in config files, assuming nothing of the above fails previously. I think, I'll have to change nginx config (something like /var/run/php5-fpm.sock -> /var/run/php7-fpm.sock). Not sure whether anything will have to be changed in IPS itself.

I wonder if anyone have tried something like this before and what the result was? Generally any tips and advice would be helpful.

Thanks!

That sounds about right. Only thing that comes to mind in general is rewrite the .htaccess (if you got one) to nginx config file.

First like to mess with PHP7.x on Debian 8.11? Adding the correct PPA usually does the trick. This walkthrough seems accurate: https://tecadmin.net/install-php7-on-debian/

Why are you running such an old version of Debian?   

Debian 9 has been stable for more than a year at this point. 

9.5 contains updated versions of both PHP and MySQL.