Uniform software and firmware management of clusters of heterogeneous server hardware

A method of upgrading an image of a virtualization software and firmware in a plurality of hosts having hardware supported by multiple hardware support managers including first and second hardware support managers, includes generating a software specification that specifies a desired state of the virtualization software and a desired state of first firmware for first hardware supported by the first hardware support manager and second firmware for second hardware supported by the second hardware support manager, preparing a desired image of the virtualization software that includes software components of the desired state of the first and second firmware, and coordinating an upgrade by (1) instructing the first and second hardware support managers to upgrade the hosts to the desired state of the first and second firmware, and (2) instructing each of the hosts to upgrade to the desired image of the virtualization software.