Methods and apparatus are provided for distributing a composite software stack as a virtual appliance. A new virtual appliance is published by obtaining a parent virtual appliance; configuring the new virtual appliance; obtaining file level differences between the parent virtual appliance and the new virtual appliance; and publishing the new virtual appliance as a patch comprising the file level differences relative to the parent virtual appliance. The file level differences comprise one or more of additions, deletions and modifications to the parent virtual appliance. An update to a given virtual appliance can be published as a fix pack, wherein the fix pack comprises file level differences relative to the given virtual appliance. An end user obtains a desired virtual appliance is obtained (for example, from a library of virtual appliances) by selecting the desired virtual appliance; obtaining metadata for the desired virtual appliance comprising an identifier of a patch file and a parent virtual appliance; and applying the patch file to the parent virtual appliance to get a modified virtual appliance.