NoCloud

The data source NoCloud allows the user to provide user-data and meta-data to the instance without running a network service (or even without having a network at all).

You can provide meta-data and user-data to a local vm boot via files on a vfat or iso9660 filesystem. The filesystem volume label must be cidata or CIDATA.

Alternatively, you can provide meta-data via kernel command line or SMBIOS “serial number” option. The data must be passed in the form of a string:

ds=nocloud[;key=val;key=val]

or

ds=nocloud-net[;key=val;key=val]

The permitted keys are:

  • h or local-hostname

  • i or instance-id

  • s or seedfrom

With ds=nocloud, the seedfrom value must start with / or file://. With ds=nocloud-net, the seedfrom value must start with http:// or https://.

e.g. you can pass this option to QEMU:

-smbios type=1,serial=ds=nocloud-net;s=http://10.10.0.1:8000/

to cause NoCloud to fetch the full meta-data from http://10.10.0.1:8000/meta-data after the network initialization is complete.

These user-data and meta-data files are expected to be in the following format.

/user-data
/meta-data

Both files are required to be present for it to be considered a valid seed ISO.

Basically, user-data is simply user-data and meta-data is a YAML formatted file representing what you’d find in the EC2 metadata service.

You may also optionally provide a vendor-data file in the following format.

/vendor-data

Given a disk ubuntu cloud image in ‘disk.img’, you can create a sufficient disk by following the example below.

## 1) create user-data and meta-data files that will be used
## to modify image on first boot
$ echo "instance-id: iid-local01\nlocal-hostname: cloudimg" > meta-data
$ echo "#cloud-config\npassword: passw0rd\nchpasswd: { expire: False }\nssh_pwauth: True\n" > user-data

## 2a) create a disk to attach with some user-data and meta-data
$ genisoimage  -output seed.iso -volid cidata -joliet -rock user-data meta-data

## 2b) alternatively, create a vfat filesystem with same files
## $ truncate --size 2M seed.iso
## $ mkfs.vfat -n cidata seed.iso

## 2b) option 1: mount and copy files
## $ sudo mount -t vfat seed.iso /mnt
## $ sudo cp user-data meta-data /mnt
## $ sudo umount /mnt

## 2b) option 2: the mtools package provides mcopy, which can access vfat
## filesystems without mounting them
## $ mcopy -oi seed.iso user-data meta-data

## 3) create a new qcow image to boot, backed by your original image
$ qemu-img create -f qcow2 -b disk.img -F qcow2 boot-disk.img

## 4) boot the image and login as 'ubuntu' with password 'passw0rd'
## note, passw0rd was set as password through the user-data above,
## there is no password set on these images.
$ kvm -m 256 \
   -net nic -net user,hostfwd=tcp::2222-:22 \
   -drive file=boot-disk.img,if=virtio \
   -drive driver=raw,file=seed.iso,if=virtio

Note: that the instance-id provided (iid-local01 above) is what is used to determine if this is “first boot”. So if you are making updates to user-data you will also have to change that, or start the disk fresh.

Also, you can inject an /etc/network/interfaces file by providing the content for that file in the network-interfaces field of metadata.

Example metadata:

instance-id: iid-abcdefg
network-interfaces: |
  iface eth0 inet static
  address 192.168.1.10
  network 192.168.1.0
  netmask 255.255.255.0
  broadcast 192.168.1.255
  gateway 192.168.1.254
hostname: myhost

Network configuration can also be provided to cloud-init in either Networking Config Version 1 or Networking Config Version 2 by providing that YAML formatted data in a file named network-config. If found, this file will override a network-interfaces file.

See an example below. Note specifically that this file does not have a top level network key as it is already assumed to be network configuration based on the filename.

version: 1
config:
   - type: physical
     name: interface0
     mac_address: "52:54:00:12:34:00"
     subnets:
        - type: static
          address: 192.168.1.10
          netmask: 255.255.255.0
          gateway: 192.168.1.254

version: 2
ethernets:
  interface0:
    match:
      mac_address: "52:54:00:12:34:00"
    set-name: interface0
    addresses:
      - 192.168.1.10/255.255.255.0
    gateway4: 192.168.1.254