Introduction to virt-sysprep (with examples)

1: Listing supported operations

Code:

virt-sysprep --list-operations

Motivation:

The motivation to use this command is to get a comprehensive list of all the available operations that can be performed with virt-sysprep. This can help users understand the capabilities of the command and plan their customization strategy accordingly.

Explanation:

The --list-operations option is used to list all the supported operations by virt-sysprep. The list includes both enabled and disabled operations. Enabled operations are indicated with asterisks (*).

Example Output:

clean,customize,files,generic-hostname,ssh-hostkeys,timezone,udev-persistent-net,upload

2: Dry run of enabled operations

Code:

virt-sysprep --domain vm_name --dry-run

Motivation:

The motivation behind performing a dry run is to preview the changes that virt-sysprep would make to the virtual machine without actually applying them. This can help users verify the expected changes and ensure that they don’t have any unintended side effects.

Explanation:

The --dry-run option is used to run all the enabled operations on the specified virtual machine (vm_name), but no actual changes are applied to the VM. This is useful for testing and verifying the operations before applying them.

Example Output:

virt-sysprep: Performing dry run
virt-sysprep: Queued operation 'boot'.
virt-sysprep: Queued operation 'customize'.
virt-sysprep: Queued operation 'edit'.
virt-sysprep: Queued operation 'hostname'.
virt-sysprep: Queued operation 'network'.
virt-sysprep: Queued operation 'rhsm-register'.

3: Running specified operations

Code:

virt-sysprep --domain vm_name --operations operation1,operation2,...

Motivation:

The motivation for running specified operations is to provide users with flexibility in customizing their virtual machines. Users can choose specific operations that they want to apply, rather than running all enabled operations.

Explanation:

The --operations option is used to specify the operations that should be run on the virtual machine (vm_name). Users can list multiple operations separated by commas. Only the specified operations will be applied to the VM.

Example Output:

virt-sysprep: Running specified operations: customize, timezone

4: Changing machine-id and host name

Code:

virt-sysprep --domain vm_name --enable customizations --hostname host_name --operation machine-id

Motivation:

The motivation behind changing the machine-id and host name is to avoid network conflicts when deploying multiple virtual machines in the same network. By generating a new machine-id and customizing the host name, each VM can have a unique identifier and network name.

Explanation:

The --enable customizations option is used to enable customizations on the virtual machine (vm_name). This allows changing the host name to avoid network conflicts. The --hostname host_name option is used to specify the desired host name. The --operation machine-id option is used to generate a new /etc/machine-id file.

Example Output:

virt-sysprep: Changing hostname to 'host_name'
virt-sysprep: Generating new /etc/machine-id file

By following the examples and explanations provided in this article, users can effectively use the virt-sysprep command to reset, unconfigure, or customize virtual machine images based on their requirements. The use cases covered in this article will help users understand the various capabilities and options of virt-sysprep for efficient VM customization and deployment.