Transient

transient is a wrapper around QEMU intended to provide higher level features like disk image downloads and shared folders, without the complexity of existing VM management solutions. transient is, as the name suggests, focused on creating virtual machines for test and development purposes that typically run for very short times. In fact transient will automatically stop any virtual machine it starts once the user is no longer connected to it.

Concepts

transient adds a few concepts on top of the standard QEMU usage. The most significant of these are:

• Disk Backend: When a new virtual disk type is specified (e.g., the vagrant centos/7:2004.01 box), the disk image will be downloaded and stored in the Disk Backend. Images at this location are read-only and will not be changed by running virtual machines. The Disk Backend is located at ~/.local/share/transient/backend by default.

• VM Store: This is the location transient uses to store the per-VM copies of disks in the Disk Backend and other VM configuraiton information. Note that transient actually uses QEMU copy-on-write files to avoid the expensive copy each time a new VM disk is created in the store. The VM Store is located at ~/.local/share/transient/vmstore by default.