cloudinit-breakout-un-deRSE23

Repo for the Breakoutsession DE-RSE/un-deRSE23-breakouts#16 of the un-deRSE23

Local Virtual Machine Setup with Cloud-Init

This tutorial guides you through setting up a virtual machine (VM) provisioned by cloud-init on your local machine using QEMU as the hypervisor. This allows you prior to deploying your VM to a public environment, that all provisioning steps are working as expected.

Prerequisites

While you can use any OS, such as a Linux distribution, macOS, or Windows, this tutorial focuses on Ubuntu 22.04 commands. Ensure you have root access for the operations.

Verify your OS version:

lsb_release -a

Expected output:

Ubuntu 22.04 jammy

Check if virtualization is supported on your system:

LC_ALL=C lscpu | grep Virtualization

Installation and Setup

Install Necessary Software

sudo apt update
sudo apt install qemu-system-x86 python3

Clone Cloud-Init Configuration

git clone git@gitlab.com:dmp4cs/server-cloud-init.git
cd server-cloud-init

Obtain a Cloud-Init Enabled Image

This tutorial employs the Debian cloud-init enabled image (opt for the generic version). Download it:

wget https://cloud.debian.org/images/cloud/bookworm/20230910-1499/debian-12-generic-amd64-20230910-1499.qcow2 -O debian.qcow2

Other distribution images are available:

• Arch Linux
• Ubuntu

Generate SSH Keys for Testing

ssh-keygen -t ed25519 -f ~/.ssh/demo

Configuration Details

meta-data

This file is utilized for specifying the hostname and instance ID.

vendor-data

This is typically provided by your cloud provider. It can remain empty for a local setup.

user-data

This primary configuration file encompasses:

• User setup with password or SSH authentication
• Cross-distribution package installations
• Shell script executions

To explore additional features, refer to the future link: TODO link

Data Sources

Cloud-init requires a method to access your config files when the VM starts for the first time. While cloud providers often facilitate this through a web interface or API, for our local setup, we'll use the NoCloud Datasource.

More about data sources can be found here.

Initiating the VM

Prepare a snapshot image:

qemu-img create -f qcow2 -b debian.qcow2 -F qcow2 snapshot.qcow2

In a new terminal, while in the same directory, initiate an HTTP server to make the files accessible to cloud-init:

python3 -m http.server

Modify Configuration

Update the user-data file by inserting your SSH key.

Start the VM with QEMU

Execute the following command:

sudo qemu-system-x86_64 -machine accel=kvm:tcg -cpu host -m 512 -nographic -drive format=qcow2,file=snapshot.qcow2 -smbios type=1,serial=ds='nocloud-net;s=http://10.0.2.2:8000/' -nic user,id=vmnic,hostfwd=tcp::5555-:22 

Explanation of Parameters:

• qemu-system-x86_64 emulate a X86-64 Bit desktop architecture
• -machine accel=kvm:tcg: Use efficient hardware virtualization when available.
• -cpu host: Emulate the host's CPU.
• -m 512: Allocate 512 MiB RAM for the VM.
• -nographic Don't emulate a GPU, text mode only
• -drive format=qcow2,file=snapshot.qcow2: Designate our snapshot as the VM's hard drive.
• -smbios type=1,serial=ds='nocloud-net;s=http://10.0.2.2:8000/': Use the specified method as a data source. More details here. The server address for the source is set as bios parameter in the virtual machine.
• -nic user,id=vmnic,hostfwd=tcp::5555-:22 setup virtual network with port forwarding for SSH from port 22 (guest) to port 5555 host

To exit QEMU, use ctrl-a x. This is first Control and A together, release and then x.

Handy Cloud-Init Commands

Check the status:

cloud-init status --wait

To execute cloud-init on the next boot:

sudo cloud-init clean --logs

Create a script or alias to reset your virtual hard drive:

rm snapshot.qcow2 && qemu-img create -f qcow2 -b debian.qcow2 -F qcow2 snapshot.qcow2