Imperative vs Declarative

vmctl supports two workflows for managing VMs.

Imperative

Use individual commands to create, configure, and manage VMs step by step:

vmctl create --name myvm --image-url https://example.com/image.img --vcpus 2 --memory 2048 --start
vmctl ssh myvm
vmctl stop myvm
vmctl destroy myvm

This is useful for:

• Quick one-off VMs
• Experimenting with different images
• Scripting custom workflows

Declarative

Define your VMs in a VMFile.kdl and let vmctl converge to the desired state:

vm "myvm" {
    image-url "https://example.com/image.img"
    vcpus 2
    memory 2048

    cloud-init {
        hostname "myvm"
    }

    ssh {
        user "ubuntu"
    }

    provision "shell" {
        inline "echo hello"
    }
}

vmctl up          # create + start + provision
vmctl down        # stop
vmctl reload      # destroy + recreate + provision
vmctl provision   # re-run provisioners only

This is useful for:

• Reproducible development environments
• Multi-VM setups
• Checked-in VM definitions alongside your project
• Complex provisioning workflows

When to Use Which