In an embodiment, a method comprises using a first server computer, executing a process that is configured to generate virtual computer instances; receiving a request to generate a first custom virtual computer instance, wherein the request identifies one or more software packages to install on the first custom virtual computer instance; copying a first pre-configured volume image onto a volume of a data storage device, wherein the volume includes one or more base software packages in a file system; mounting the volume to the first server computer, in response to receiving the request; installing each of the one or more software packages on the volume; unmounting the volume; creating a snapshot of the volume; registering the snapshot as a registered custom volume image.