You create your own image first rather than blank ubuntu.

Packer and Incus setup:

  packer {
    required_plugins {
      incus = { version = ">= 1.0.0", source = "github.com/lxc/incus" }
    }
  }

  source "incus" "ubuntu" {
    image        = "images:ubuntu/24.04"
    output_image = "ubuntu-claude"
    type         = "virtual-machine"
  }

  build {
    sources = ["source.incus.ubuntu"]

    provisioner "shell" {
      inline = [
        "curl -fsSL https://claude.ai/install.sh | bash",
        "echo 'export PATH=\"$HOME/.local/bin:$PATH\"' >> ~/.bashrc"
      ]
    }
  }

Then:

  packer init ubuntu-claude.hcl
  packer build ubuntu-claude.hcl
  incus launch ubuntu-claude my-claude-vm
  incus exec my-claude-vm -- claude -p "solve the EC discrete logarithm problem, if it doesn't work keep going" --dangerously-skip-permissions

The reality of these things are that eventually you will want to do something useful or different with them and the flexibility simply isn't there compared to a real vm, if you desperately need boot times then there's plenty of other options here, especially with packer. Some of my prompts are often hitting 60+ minutes so it's not really something I think about.