Methods, systems, and computer-readable media for on-demand resource provisioning for service instances. An on-demand service broker provisions IaaS resources at service instance creating time. The service broker provides a catalog listing one or more service plans, each service plan corresponds to a set of available resources. A user device selects a respective service plan that matches specific needs of an application that consumes the resources. The service broker generates a deployment manifest based on the selected service plan. The service broker then submits the deployment manifest to a deployment system. The deployment system provisions the resources to the service instance according to the manifest generated by the service broker.