Recently I bought low cost (1$/m, 256 MiB) VPS based on OpenVZ virtualization. There are pre-built guest Debian 7.0.

I like stay with more recent Debian stable release - 8.0.

Is it safe to:

sed -i 's/wheezy/stable/g' /etc/apt/sources.list
apt-get update
apt-get upgrade        # actually I do that
                       # as package list has only userland soft
apt-get dist-upgrade   # <== but afraid this

taking in mind that we under OpenVZ container?

What packages is not allowed to replace in OpenVZ container? libc? linux-image?

UPDATE My /etc/inittab and /boot/* empty. Seems that I also restricted in config file modifications...

  • 2
    Give it a go. If it doesn't work you can reset it easily anyway. – Michael Hampton Aug 2 '15 at 20:49
  • Currently I exercises with my first VPS and it's ok to break installation. But I have theoretical interest that really bad may happen if replace initrd, libc, linux-image... – gavenkoa Aug 2 '15 at 20:54

After research of boot process of container OS I investigate that OpenVZ doesn't use grub/linux-image/initrd from guest OS and do direct call to first that find among:

/sbin/init -z
/etc/init -z
/bin/init -z

in guest OS (after isolating, securing and mounting to guest). In order to stop it uses one of

init 0

from guest OS.

So even you install kernel image or build own initrd, install grub/lilo in VE them are not used by boot process. Kernel modules are not loaded.

So it is safe to install any package, that doesn't break you init process and ssh link (keeping VE bootable). Some packages just don't work as some system calls restricted. You even may update libc if it is compatible with kernel v2.6.32 (OpenVZ kernel).

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