cloud-init ubuntu nocloud example with network config

.gitignore

*.img
*.raw

README.md

Boot Ubuntu providing it network config in NoCloud Datasource

Ubuntu images can be booted with an additional disk that provides user-data, meta-data and network configuration. This is described some in the upstream documentation.

But this example allows for more easily tinkering.

See a screencast of this on asciinema.org.

What is here

A brief description of files here.

• check-dependencies: check that all dependencies are available. It will give you an apt-get command to install any missing packages.

• get-image: download an ubuntu disk image from cloud-images.ubuntu.com

• boot: wrapper around calling qemu-system-x86_64 as those command lines are not so friendly. It will pass through additional arguments to qemu.

• network-config-v1.yaml, network-config-v2.yaml: network config files version 1 and version 2 from upstream doc

• user-data.yaml: example user-data that sets password for login. Note that not all user-data is required to be yaml formatted, but this example is '#cloud-config' which is yaml.

• meta-data.yaml: example meta-data for nocloud.

Usage

Heres an example walking through how to use this.

• Verify dependencies

  $ ./check-dependencies
  All good. (cloud-localds genisoimage qemu-img qemu-system-x86_64 wget)
  

• Download an image

  Original images are compressed qcow2. get-image downloads an original image and converts it to 'raw' format. This is not strictly necessary, but booting a compressed qcow2 directly means that all disk reads go through decompression.

  $ ./get-image xenial
  downloading <...>
  dist: xenial-server-cloudimg-amd64-disk1.img
  raw:  xenial-server-cloudimg-amd64.raw
  

• Build a seed image from provided files

  cloud-localds creates an iso9660 filesystem with expected content. Specifically the filesystem label is 'cidata', and the top level directory has 'meta-data', 'user-data', and 'network-config' files. network-config is optional.

  $ cloud-localds -v --network-config=network-config-v1.yaml \
      seed.img user-data.yaml meta-data.yaml
  wrote seed.img with filesystem=iso9660 and diskformat=raw
  

• Create a qcow2 disk named 'disk.img' backed by the raw image

  By using a qcow image backed by the raw, we can avoid modifying the original.

  $ qemu-img create -f qcow2 -b xenial-server-cloudimg-amd64.raw disk.img
  

• Boot the image

  By default, boot will run qemu in vga graphics mode, and create a window on your system. It will boot to a login prompt and you can login with username ubuntu and password passw0rd.

  I like to boot with qemu's -nographic option, which will display the full boot in a terminal which is better for demos. See a full boot log here

  Some things to look at once you've logged in

  $ cat /run/cloud-init/result.json
  {
   "v1": {
    "datasource": "DataSourceNoCloud [seed=/dev/sr0][dsmode=net]",
    "errors": []
   }
  }
  
  $ grep -v '^[#]' /etc/network/interfaces.d/50-cloud-init.cfg
  auto lo
  iface lo inet loopback
  
  auto interface0
  iface interface0 inet static
      address 192.168.1.10/24
      gateway 192.168.1.254
  
  $ grep INFO /var/log/cloud-init.log 
  2017-11-03 18:10:18,785 - stages.py[INFO]: Loaded datasource DataSourceNoCloud - DataSourceNoCloud [seed=/dev/sr0][dsmode=net]
  2017-11-03 18:10:18,964 - stages.py[INFO]: Applying network configuration from ds bringup=False: {'config': [{'type': 'physical', 'mac_address': '52:54:00:12:34:00', 'name': 'interface0', 'subnets': [{'netmask': '255.255.255.0', 'gateway': '192.168.1.254', 'type': 'static', 'address': '192.168.1.10'}]}], 'version': 1}
  2017-11-03 18:10:22,954 - cc_apt_configure.py[INFO]: No custom template provided, fall back to builtin
  

boot

#!/bin/sh
Usage() {
    cat <<EOF
Usage: ${0##*/} disk.img seed.img [qemu [additional [args]]]
EOF
}
fail() { echo "$@" 1>&2; exit 1; }

set -f
[ "$1" = "-h" -o "$1" = "--help" ] && { Usage; exit; }
[ $# -ge 2 ] || { Usage 1>&2; exit 1; }
disk=$1
seed=$2
shift 2
[ "$1" = "--" ] && shift

[ -f "$disk" ] || fail "$disk: not a file"

# provide 'format=' correctly so qemu doesnt complain. (qcow2 or raw)
fmt=$(qemu-img info "$disk" | awk -F: '$1 == "file format" { print $2 }')
fmt=${fmt# }

# add -m 768 if no '-m' present.
args=" $* "
[ "${args##* -m}" = "-m" ] || set -- "$@" -m 768

MAC=${MAC:-52:54:00:12:34:00}
set -- \
qemu-system-x86_64 -enable-kvm \
    -netdev type=user,id=net00 \
    -device virtio-net-pci,netdev=net00,mac=${MAC} \
    -drive file=$disk,id=bootdisk,if=none,format=$fmt,index=0 \
    -device virtio-blk,drive=bootdisk \
    -drive file=$seed,id=seed,if=none,format=raw,index=1 \
    -device virtio-blk,drive=seed \
    "$@"

echo "$@" 1>&2
"$@"

# vi: ts=4 expandtab

check-dependencies

#!/bin/sh
MISSING=""
FOUND=""
checkdep() {
    local exe="$1" package="$2" upstream="$3"
    if command -v "$1" >/dev/null 2>&1; then
        FOUND="${FOUND:+${FOUND} }$exe"
        return "0"
    fi
    MISSING=${MISSING:+${MISSING }$package}
    echo "missing $exe."
    echo "  It can be installed in package: $package"
    [ -n "$upstream" ] &&
        echo "  Upstream project url: $upstream"
    return 1
}

checkdep cloud-localds cloud-image-utils http://launchpad.net/cloud-utils
checkdep genisoimage genisoimage
checkdep qemu-img qemu-utils http://qemu.org/
checkdep qemu-system-x86_64 qemu-system-x86 http://qemu.org/
checkdep wget wget

if [ -n "$MISSING" ]; then
    echo
    [ -n "${FOUND}" ] && echo "found: ${FOUND}"
    echo "install missing deps with:"
    echo "  apt-get update && apt-get install ${MISSING}"
else
    echo "All good. (${FOUND})"
fi

# vi: ts=4 expandtab

get-image

#!/bin/sh

Usage() {
    cat <<EOF
Usage: ${0##*/} release

   release is like 'xenial' or 'artful'.
    - Downloads an image from cloud-image.ubuntu.com
    - converts it to raw format (from qcow2)
EOF
}
fail() { echo "$@" 1>&2; exit 1; }

rel="$1"
[ "$1" = "-h" -o "$1" = "--help" ] && { Usage; exit 0; }
[ -n "$rel" ] || { Usage 1>&2; fail "Must give release"; }

arch="amd64"
burl="${_PROTO:-https}://cloud-images.ubuntu.com/daily/server"
fname=$rel-server-cloudimg-amd64.img
ofname="$fname"

# trusty and xenial have a '-disk1.img' while
# other releases have just 'disk.img'
case "$rel" in
    precise|trusty|xenial) ofname="$rel-server-cloudimg-amd64-disk1.img";;
esac

raw="${fname%.img}.raw"
if [ ! -f "$fname" ]; then
    url="$burl/$rel/current/$ofname" 
    echo "downloading $url to $fname"
    wget "$url" -O "$fname.tmp" &&
        mv "$fname.tmp" "$fname" || exit
    rm -f "$raw"
fi
if [ ! -f "$raw" ]; then
    echo "converting $fname to raw in $raw"
    qemu-img convert -O raw "$fname" "$raw.tmp" &&
        mv "$raw.tmp" "$raw" || exit
    rm -f "$pfname"
fi

echo "dist: $ofname"
echo "raw:  $raw"

# vi: ts=4 expandtab

meta-data.yaml

instance-id: 506f2788-9741-4ed8-af53-c6a21383d09a

network-config-v1.yaml

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

network-config-v2.yaml

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

user-data.yaml

#cloud-config
password: passw0rd
chpasswd: { expire: False }
ssh_pwauth: True