One Instance of Linux inside other

lazyperlcoder

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Hi there!

I have very generic question: Is it possible to run Linux server inside other server instance without virtualization?

Context: I got new job and I have to get familiar with a complex system comprised of several components - one of them is an application server based on CentOS 6 kernel. I don´t have any detailed technical documentation, just user documentation which deals mainly with GUI and top level functionality. This application was created around years 2006-2009. The interesting fact is deployment. Big installation package - containing kernel, several libraries and core of Python scripts providing special functions - is uploaded to the host OS, then several sh files (about 4k LOC) do install files to correct paths, initiate yum, ssh server and so on. The guest server is initiated via twistd daemon.

I have worked with Linux servers in the past, but I haven´t met this way of deployment. Therefore my second question would be: Has this technique some conventional name? The process of installation reminds me how dockerfile / docker-compose work, but it is of course not Docker based.

Thank you.

Lazy Perl Coder
 
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f33dm3bits

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Don't use CentOS6, it's End of Life and not getting anymore updates, use a supported version that is still supported and receiving updates. That's the definition of virtualization running a server on top of another server, being able to use the host system's resources.
 

lazyperlcoder

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Don't use CentOS6, it's End of Life and not getting anymore updates, use a supported version that is still supported and receiving updates. That's the definition of virtualization running a server on top of another server, being able to use the host system's resources.
Hi, thanks for the answer. I am aware that CentOS6 reached EOL. Just comment: In system with high complexity is not so easy to make an upgrade. (This system is yet maintained by external vendor anyway.)

I was referring to very specific way, how the virtualization was achieved.
 

f33dm3bits

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Hi, thanks for the answer. I am aware that CentOS6 reached EOL. Just comment: In system with high complexity is not so easy to make an upgrade. (This system is yet maintained by external vendor anyway.)

I was referring to very specific way, how the virtualization was achieved.
I only have experience with KVM/QEMU for for virtualization, the way of virtualization that you describe doesn't sound familiar to me and have not come across it when having searched for virtualization solutions in the past. It may be hard to upgrade but eventually it will have to be upgrade and running End of Life systems is a security risk.
 

gvisoc

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Hi there!

I have very generic question: Is it possible to run Linux server inside other server instance without virtualization?
...

Thank you.

Lazy Perl Coder
That sounds like when we use chroot to test a development kernel that drags with itself a lot of unstable dependnecies. Check this as a lead to read more: chroot and kernels

The only thing is that we would only be able to run one kernel at a time without a virtualisation solution, so probably that deployment included some extra steps to reboot in that chrooted environment. I don't know how twistd works, but that may be worth to check if it's the missing link in all this.
 

lazyperlcoder

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Thank you very much for all answers. I went again through the code and I found out, what is going on. My previous assumption was wrong - it is not kind of virtualization but automated installation. It is called Kickstart. I am sorry, because my initial description was misleading. I was not aware about this method and I thought it was part of custom code.
 

f33dm3bits

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Thank you very much for all answers. I went again through the code and I found out, what is going on. My previous assumption was wrong - it is not kind of virtualization but automated installation. It is called Kickstart. I am sorry, because my initial description was misleading. I was not aware about this method and I thought it was part of custom code.
Kickstart isn't virtualization but a way of automatically deploying installations.
 
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