[Users] Local VM for testing production VM

[Scott Dowdle]

Greetings,

----- Original Message -----
> Hi Everyone,
> 
> We are a free/open source project. We rent a OpenVZ-based CentOS 7 VM
> for a website and wiki. We need to get off PHP 5.4 and MediaWiki
> 1.26.
> 
> I'm setting up a local VM to test the migration of the production VM.
> I have a few questions.
> 
> 1. Is there a way to clone a rented VM over SSH?
>     - an exact image would be great to use for testing
> 
> 2. Is there a tool which duplicates a configuration?
>     - we would like to use the production config for the local config
> 
> 3. What are the interesting items in a config for testing?
>    - high level bullet points
> 
> For question (1), we don't get a lot of support from the provider. We
> mostly have to rely on things we can do at the user side of things.
> 
> My apologies for (3). I know it is a crummy question. We have an idea
> we want the same repos and packages, but we are not sure what else
> may
> contribute to the config in a significant way.
> 
> Jeff

The ideal way to back it up would be to have access to the host the VM (or container) is running on... and stop the VM, and then rsync its disk image and config wherever you want it.

Outside of having access to the physical host the VM is running on... you can just use traditional backup tools. One of the most basic things to do is use rsync.  You can rsync everything you care about from the machine while it is running... so you get the bulk of it.  When done, you can stop all network facing services and then do another rsync.  That will at least get you a someone consistent backup.  It isn't a bare-metal backup, but it is better than nothing.

There are also ways to make snapshots on the host and then backup from snapshot... so you get a complete and consistent backup... but again... those require administrative access to the host node or some very advanced, user-facing control panel with those features.

The configs are generally a single text file for each VM/container... and are somewhat human readable... so anything you see in there you should be able to decipher (again if you have access to the VM host).  There are usually man pages on the config files or the various tools used to make the configs (prlctl, virsh, etc).  The configuration items you can gather from within the VM/container are the network settings, amount of RAM, CPU, and disk size... and then the various config files for your active services, accounts etc.  Various basic command line commands can give you that info.

If you have any additional and/or specific questions about anything I mentioned, feel free to ask follow-up questions.  Perhaps other have additional answer/options they could share.

TYL,
-- 
Scott Dowdle
704 Church Street
Belgrade, MT 59714
(406)388-0827 [home]
(406)994-3931 [work]