How to use the command 'krunvm' (with examples)

The ‘krunvm’ command is used to create and manage MicroVMs (lightweight virtual machines) from OCI images. MicroVMs provide an isolated environment for running applications, making them a secure and efficient solution for deploying containerized workloads.

Use case 1: Create MicroVM based on Fedora

Code:

krunvm create docker.io/fedora --cpus number_of_vcpus --mem memory_in_megabytes --name "name"

Motivation:

This example demonstrates how to create a MicroVM based on the Fedora OCI image. By specifying the number of virtual CPUs (number_of_vcpus), memory allocation (memory_in_megabytes), and providing a name for the MicroVM (name), you can customize the resources and identification of the newly created MicroVM.

Explanation:

• docker.io/fedora: The OCI image used as the base for the MicroVM.
• --cpus number_of_vcpus: Specifies the number of virtual CPUs allocated to the MicroVM.
• --mem memory_in_megabytes: Sets the memory allocation for the MicroVM in megabytes.
• --name "name": Assigns a name to the MicroVM.

Example output:

MicroVM 'name' based on 'docker.io/fedora' created successfully.

Use case 2: Start a specific image

Code:

krunvm start "image_name"

Motivation:

This example demonstrates how to start a specific OCI image as a MicroVM. Once a MicroVM is created, it can be started using this command to launch the desired application or workload contained within the image.

Explanation:

• "image_name": The name of the image to be started as a MicroVM.

Example output:

MicroVM running with image 'image_name'.

Use case 3: List images

Code:

krunvm list

Motivation:

This example illustrates how to list all the available MicroVM images. It provides an overview of the existing MicroVMs, allowing you to quickly reference and manage them.

Example output:

Available MicroVM images:
- Image 1
- Image 2
- Image 3

Use case 4: Change a specific image

Code:

krunvm changevm --cpus number_of_vcpus --mem memory_in_megabytes --name "new_vm_name" "current_vm_name"

Motivation:

This example showcases how to modify the resources and name of an existing MicroVM. By changing the virtual CPU count (number_of_vcpus), memory allocation (memory_in_megabytes), and providing a new name for the MicroVM (new_vm_name), you can adapt the MicroVM to meet your evolving needs.

Explanation:

• --cpus number_of_vcpus: Specifies the new number of virtual CPUs allocated to the MicroVM.
• --mem memory_in_megabytes: Sets the new memory allocation for the MicroVM in megabytes.
• --name "new_vm_name": Assigns a new name to the MicroVM.
• "current_vm_name": The name of the MicroVM to be modified.

Example output:

MicroVM 'current_vm_name' changed successfully.
New configuration:
- CPUs: number_of_vcpus
- Memory: memory_in_megabytes
- Name: new_vm_name

Use case 5: Delete a specific image

Code:

krunvm delete "image_name"

Motivation:

This example demonstrates how to delete a specific MicroVM image. Removing unnecessary or outdated MicroVMs helps to free up resources and maintain a clean environment.

Explanation:

• "image_name": The name of the image to be deleted.

Example output:

MicroVM 'image_name' deleted successfully.

Conclusion:

The ‘krunvm’ command provides a convenient way to create, manage, and delete MicroVMs from OCI images. With its simple syntax and various options, it allows you to customize the resources and configurations of the MicroVMs. By leveraging the power of MicroVMs, you can ensure the security and efficiency of your containerized workloads.