I have researched this question quite a lot on stackexchange but my thoughts are inconclusive, the different licenses involved and options by the distribution vendors are giving me a headache.
My question is basically if there is any way around the high fees the distribution vendors are charging for their professional solutions if one is just casually (by casually I mean low volume sales but with commercial intent, not as a private hobby) developing and selling embedded devices (i.e. 20-30 devices p.a.).
Now to my concrete case:
Suppose I'd want to setup an embedded device and want to use a FOSS operating system (Debian, Ubuntu, any non commercial Linux distribution for instance) in a commercial setup, i.e. as a gateway computer. These are typically licensed with parts of GPL, LGPL, GPLv2, GPLv3 and other, more permissive licenses.
Suppose I automatically install (and most definitely update) a database on this system with the package manager but the package repository itself provided by the database developer. Suppose the database and all its accompanying software is licensed with Apache 2.0, BSD or MIT license. And suppose I do develop a program that gets executed on this operating system. The program should perform operations in connection with the OS, i.e. make IO operations from Ethernet to the database, maybe provide a server but there is no compiling or heavy shell scripting (maybe only to start an update routine) involved, perhaps a ssh connection may be used for maintenance.
Suppose I wanted to sell a pre-configured device with a FOSS OS, some Apache 2.0 and MIT licensed programs and own compiled source code along with the system to a customer. Do I then have to disclose my source code to customers, according to the GPL?
If not (meaning the stated above is in accordance to the GPL): Which pitfalls might occur?
If yes (meaning the stated above would violate the GPL and I'd need to disclose my source code): Does providing the device (the embedded device is kept as a property of mine) and just charging a monthly/yearly service fee change the situation (I think, as far as I understand this answer (although in that and this case the device was intended to be lend) here, not)?
A similar case is discussed here:
But in this case the aspect of maintenance and (re)installing/updating system components (i.e. if a security risk bug is fixed and a system program need to be updated) is not addressed
This answer gives an insight to the above problematic. But my question remains: Is using the system's package manager to update system parts in an automated fashion and using system interfaces considered "intimate enough" or is this perfectly in accordance to the GPL?
In this answer I understand that if I do what I stated above I have to be prepared to provide full source code for 3 years
I want to thank you for taking the time reading through this wall of text and furthermore thank you in advance for providing me with an answer.