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| computing:preseed [2024/02/17 17:52] – oemb1905 | computing:preseed [2024/02/17 18:01] (current) – oemb1905 |
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| I created my own virtualization stack which is complete with version control, file backups, full image backups and more. Additionally, because my client base and use-case does not require that I spin up VMs too often, it was very easy to just keep a few VMs pre-configured generically and then virt-clone them upon need and then tweak a few settings. However, my use-cases and needs are expanding and so I wanted to be able to spin up a new VM with a shell script and have a super minimal and clean copy of Debian installed on it, with absolutely no network configuration, extra packages, etc. So, I decided to dig deeper into both qemu and libvirt to see if there was something that could be developed. After working on qemu options for a bit, I decided that libvirt fit my needs better. After studying forums, I saw that Debian had an "auto-installer" feature and that you could pass configs to it through virsh by adding a few xml lines. After a little trial and error with using a remote site for the config vs. localhost, I developed the following recipe: | I created my own [[https://wiki.haacksnetworking.org/doku.php?id=computing:vmserver|virtualization stack]] about two and a half years ago. As I expanded and needed to spin up VMs, my first strategy was to create model VMs that fit particular use cases and then ''virt-clone'' those and then adapt to the new use case. Over time, this became cumbersome, and I started having use-cases that did not fit the templates. For this reason, it came to time to automate fresh Debian installs on new VMs. After studying forums, I saw that Debian had an "auto-installer" feature and that you could pass configs to it through virsh by adding a few xml lines. After a little trial and error with using a remote site for the config vs. localhost, I learned that you could pass the preseed config file to virsh with the last line in this block: |
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| virt-install --name=domain.org.qcow2 \ | virt-install --name=domain.org.qcow2 \ |
| --initrd-inject /mnt/vms/cfgs/preseed.cfg | --initrd-inject /mnt/vms/cfgs/preseed.cfg |
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| Other resources online insisted that I needed to add something like --extra-args="ks=file:/mnt/vms/cfgs/preseed.cfg console=tty0 console=ttyS0,115200" to the recipe as well, but I found that was unnecessary through trial and error. I think that syntax is required for those desiring kickstarter and/or if they are not using standard X passthrough for the shell. I'm not sure though. After I got the installer to recognize configuration file, I then began making a list as to which options worked automatically and which did not. One by one, I checked the stock configuration file here and adjusted my config until everything worked. Below, I've linked the stock configuration file I used as a jumping off point, and the one I developed for my use-case. | Other resources online insisted that I needed to add something like --extra-args="ks=file:/mnt/vms/cfgs/preseed.cfg console=tty0 console=ttyS0,115200" to the recipe as well, but I found that that was only required for those desiring kickstarter and/or if they are using a remote site to host the configs from. My next task was to check the stock configuration file and create my own preseed config that would create machines as I desired. Here's the stock Debian config and the one I developed: |
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| * [[https://www.debian.org/releases/stable/example-preseed.txt|Stock Configuration]] | * [[https://www.debian.org/releases/stable/example-preseed.txt|Stock Configuration]] |
| * [[https://repo.haacksnetworking.org/haacknet/haackingclub/-/blob/main/scripts/preseeds/external/preseed.cfg?ref_type=heads|My Use-Case]] | * [[https://repo.haacksnetworking.org/haacknet/haackingclub/-/blob/main/scripts/preseeds/external/preseed.cfg?ref_type=heads|My Use-Case]] |
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| After getting the virt-install recipe and config to perform the desired Debian install, my next task was to automate all of this with a simple script that would create a virtual hard disk of any desired size and a libvirt entry with my desired naming convention in my production VM directory. Here's what I came up with: | My next task was to automate all of this with a simple shell script. Here's what I came up with: |
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| #!/bin/bash | #!/bin/bash |
| --initrd-inject /mnt/vms/cfgs/external/${hostname}/preseed.cfg | --initrd-inject /mnt/vms/cfgs/external/${hostname}/preseed.cfg |
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| For now, I just need really simple Debian VMs as quickly as possible. However, as I wrote this, I began to realize that I could easily expand this script to meet the needs of a variety of different use cases, could add conditionals to it, validation and more. Down the road, I plan to do that, and you can stay up to date with how I expand this script's functionality on the Hacking Club repository: | This script prompts me for domain name and size of the virtual hard disk. I will likely expand the script to add more parameters down the road, such as but not exclusive to networking, vdd location, ram, and so on. As I expand this, I will update the wiki here and also push my latest scripts and configs to the repository: |
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| * [[https://repo.haacksnetworking.org/haacknet/haackingclub/-/tree/main/scripts/preseeds?ref_type=heads|Preseed Project]] | * [[https://repo.haacksnetworking.org/haacknet/haackingclub/-/tree/main/scripts/preseeds?ref_type=heads|Preseed Project]] |
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| --- //[[jonathan@haacksnetworking.org|oemb1905]] 2024/02/17 17:42// | --- //[[jonathan@haacksnetworking.org|oemb1905]] 2024/02/17 17:53// |
