Now I have problems with one of my VPSs. My hosting provider declared me, that problems may be caused by executing apt-get upgrade inside my VPS (Ubuntu 14.04.1 LTS x64, OpenVZ) and that it is bad idea at all.
I have tried to find in the Web any arguments in favor of this point of view but have not find any convincing one.
Is it really bad idea to do apt-get upgrade inside OpenVZ container?
Assuming the server setup is sane and you are upgrading within a stable release (upgrading to a new major version or following a development release is a different thing) then apt-get upgrade should not normally be a problem and needs to be done to get security fixes.
It sounds like your hosting provider has screwed up big time on preparing their images. If they can't find a soloution that allows you to apply normal distribution updates to your server then it;s time to vote with your feet.
Some qualifiers apply, in case you upgrade components that depend on a newer kernel (than your OpenVZ host provides).
In principle this means some co-ordination with the host might be necessary. E.g. it would be unwise to upgrade 14.04 -> 16.04 without checking whether the host would support it.
Otherwise no. It is the responsibility of the container to apply security updates. Hosting which tells you not to run the provided security update mechanism, would be unsuitable for internet use.
