Which open source tool do you use most often to manage your virtual machines?
When it comes to managing virtual machines, there is no shortage of open source tools out there to choose from. Whether you are trying to virtualize a whole data center worth of servers in a cloud environment, test out a new operating system on your desktop, or something in between, it's important to choose the right tool for the job.
Some virtual machine tools ship as all-in-one solutions, like VirtualBox. For professional and enterprise open source users in a Linux environment, there's a good chance you're using the KVM virtualization abilities built right into your kernel as your hypervisor, or perhaps an alternative like Xen, and at least one other tool as an abstraction layer to manage the virtual machines you launch. Perhaps it's a simple command-line tool like virsh, a desktop tool like Virtual Machine Manager, an advanced tool like oVirt, or perhaps even managing them as a part of a cloud with an open source tool like OpenStack.
We can't possibly list all of the potential options for tools you might consider, so in lieu of trying and failing at generating a complete list, we've listed some of our favorites here, and invite you to fill in with your other preferred tools in the comments below. What tools do you use for managing virtual machines, and why? Do you use one of these? Maybe a virtual environment manager, like Vagrant? Share your virtualization toolchain with us!