Build QCOW, VirtualBox and Vagrant images

Requirements:

• Packer
• Either qemu or VirtualBox functioning in the build host
• a cOS or a custom ISO
• Packer templates

The suggested approach is based on using Packer templates to customize the deployment and automate creation of QCOW, Virtualbox and Vagrant images of cOS derivatives or cOS itself. For all the details and possibilties of Packer check the official documentation.

Run the build with Packer

To build QCOW and VirtualBox images an ISO file is required. You can either Download a cOS ISO or build your own from a container image.

QCOW2

Consider:

# From the root of a cOS-toolkit repository checkout

> cd packer
> packer build -var "iso=/path/to/image.iso" -only qemu.cos .

The process should end up by building a .box file (vagrant image) and a .tar.gz file (containing the raw disk) in the same folder:

...
==> qemu.cos (compress): Using pgzip compression with 8 cores for cOS_green_dev_amd64.tar.gz
==> qemu.cos (compress): Tarring cOS_green_dev_amd64.tar.gz with pgzip
==> qemu.cos (compress): Archive cOS_green_dev_amd64.tar.gz completed
Build 'qemu.cos' finished after 4 minutes 34 seconds.

==> Wait completed after 4 minutes 34 seconds

==> Builds finished. The artifacts of successful builds are:
--> qemu.cos: 'libvirt' provider box: cOS_green_dev_amd64.box
--> qemu.cos: compressed artifacts in: cOS_green_dev_amd64.tar.gz

> ubuntu@jumpbox:~/cOS-toolkit/packer$ ls -liah
total 2.3G
 516552 drwxrwxr-x  4 ubuntu ubuntu 4.0K Jul 30 07:54 .
 516207 drwxrwxr-x 14 ubuntu ubuntu 4.0K Jul 30 07:41 ..
 516362 -rw-r--r--  1 root   root   1.2G Jul 30 07:54 cOS_green_dev_amd64.box
 516385 -rw-r--r--  1 root   root   1.2G Jul 30 07:54 cOS_green_dev_amd64.tar.gz
 516553 -rw-rw-r--  1 ubuntu ubuntu  389 Jun 28 08:07 config.yaml
 516339 -rw-rw-r--  1 ubuntu ubuntu 6.5K Jul 30 07:41 images.json.pkr.hcl
1818463 drwxrwxr-x  3 ubuntu ubuntu 4.0K Jul 30 07:49 packer_cache
1818400 drwxrwxr-x  2 ubuntu ubuntu 4.0K Jul 30 07:41 user-data
 516555 -rw-rw-r--  1 ubuntu ubuntu  606 Jun 28 08:07 vagrant.yaml
 516340 -rw-rw-r--  1 ubuntu ubuntu 6.1K Jul 30 07:41 variables.pkr.hcl
ubuntu@jumpbox:~/cOS-toolkit/packer$ 

The -only qemu.cos flag is just to tell packer which of the sources to make use for the build. Note the packer/images.json.pkr.hcl file defines few other sources such as amazon-ebs and virtualbox-iso.

Virtualbox

Similarly, to build OVA images we run:

# From the root of a cOS-toolkit repository checkout

> cd packer
> packer build -var "iso=/path/to/image.iso" -only virtualbox-iso.cos .

Vagrant

To build vagrant images, we enable the vagrant feature, which allows the vagrant user to login afterwards:

# From the root of a cOS-toolkit repository checkout

> cd packer
> packer build -var "iso=/path/to/image.iso" -var "feature=vagrant" -only virtualbox-iso.cos .

Customize the build with a variables file

The packer template can be customized with the variables defined in packer/variables.pkr.hcl. These are the variables that can be set on run time using the -var key=value or -var-file=path flags. The variable file can be a json file including desired varibles. Consider the following example:

# From the packer folder of the cOS-toolkit repository checkout

> cat << EOF > test.json
{
    "root_username": "root",
    "root_password": "cos"
}
EOF

> packer build -only qemu.cos -var "iso=/path/to/image.iso" -var-file=test.json .

The above example runs the build by logging with a different username/password to run the installation.

Default cloud-init

In the packer folder there is present a config.yaml file which can be used to customize the image. The file is in cloud-init style and will be automatically installed by default when running elemental install.

Available variables for customization

All the customizable variables are listed in packer/variables.pkr.hcl, these are some of the relevant ones:

• build,flavor,arch: This to personalize the artifact output name. The artifact output format is "cOS_${var.flavor}_${var.build}_${var.arch}.tar.gz"

• disk_size: This sets the disk size to be used for the image. It is 50000 by default, and expressed in MB.

• memory: RAM to allocate to the VM in MB.

• cpu: Number of processors of the VM

• accelerator: Accelerator type, see the official docs

• root_username: Username used to login via ssh, it needs root permissions to be able to run the installation process and call elemental install

• root_password: Password for the user specified in root_username

• feature: Enable/Disables specific cOS features.