Testing with ConfigDrive and cloud-init

cloud-init

cloud-init is a very easy way to bootstrap/configure Virtual Machines running in a cloud environment. It can read it’s metadata from various data sources and configure for public SSH keys or create users for example.

Most large clouds support cloud-init to quickly deploy new Instances.

Config Drive

Config Drive is a data source which reads a local ‘CD-Rom’ device which contains the metadata for the Virtual Machine. This allows for auto configuration of Virtual Machines without them requiring network. My main use case for Config Drive is CloudStack which has support for Config Drive since version 4.11.

I wanted to test with Config Drive outside CloudStack to test some functionality.

meta_data.json

On my laptop I spun up a Ubuntu 18.04 Virtual Machine with cloud-init installed and I attached a ISO which I created.

/home/wido/Desktop/
             cloud-init/
               openstack/
                 latest/
                   meta_data.json

In meta_data.json I put:

{
  "hostname": "ubuntu-test",
  "name": "ubuntu-test",
  "uuid": "0109a241-6fd9-46b6-955a-cd52ad168ee7",
  "public_keys": [
      "ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAwPKBJDJdlvOKIfilr0VSkF9i3viwLtO8GyCpxL/8TxrGKnEg19LPLN3lwKWbbTqBZgRmbrR3bgQfM4ffPoTCxSPv44eZCF8jMPv8PxpC0yVaTcqW4Q7woD7pjdIuGVImrmEls0U8rS3uGQDx7LhFphkAh+blfUtobqzyHvqcbtVEh+drESn8AXrKd1MZfGg6OB8Xrfdr6d959uHBHFJ8pOxxppYbInxKREPb3XmZzmoNQUmqFRN/VNVTreRHAxDcPM8pEPuNmr3Vp+vDVvfpA58yr2rZ21ASB4LlNOOSEx7vnLd6uH9rsqAJOtr0ZEE29fU609i4rd6Zda2HTGQO+Q== wido@wido-laptop",
      "ssh-rsa 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 wido@wido-desktop"
  ]
}

Using mkisofs I was able to create a ISO and attached it to the VM:

mkisofs -iso-level 3 -V 'CONFIG-2' -o /var/lib/libvirt/images/cloud-init.iso /home/wido/Desktop/cloud-init

The ISO was attached to the Virtual Machine and after reboot I could log in with the user ubuntu over SSH using my pubkey!

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Wido den Hollander

I am the CTO at PCextreme B.V. and i will keep this blog just to post some interesting information about my daily work on Linux (and other) systems.