I have unfortunately a big concern.
Percona for MySQL is under GPL v2 license.
Does it mean that if we sell a solution using Percona for MySQL to a customer, we have to provide the source code of our solution ?
We can be protected by purchasing a commercial license. Unfortunately Percona doesn’t provide any license.
So what is the solution, for delivering a software product using Percona for MySQL, to not provide our software source code and to not violated anything ?
We cannot provide legal answers here, you should only rely on the legal advice from the legal team you work with, but I can review the situation hypothetically.
My reading of GPL v2 license is that this license requires shipping source code only for derivative products, where derivative is defined as direct changes to source code or library linking to code under GPL v2.
Reading your question, I make a hypothetical assumption that you do not make changes to source code of Percona Server, but likely you communicate with the server over network. Likely it means that your application is linked with libmysql library, which is also under GPL v2 license, and it means you would need to provide the source code of the application that linked to libmysql.
Hypothetically one of solution would be to link to the library that provides similar functionality as libmysql but under more permissive license. I know that there is one provided by MariaDB, so it would help to avoid the license violation.
So, hypothetically, if your application is linked against library provided by MariaDB and you connect to Percona Server over network, then to satisfy GPL v2 requirement you would need only to provide the source code of Percona Server, which is quite easy to do by pointing to our website or github repo.
Nothing in this answer should be taken as legal reading of GPL v2 and treated as Percona’s approval to use our server in that or another specific way.