Cloud providers stipulate a variety of resources such as CPUs, memory, and storage in the form of Virtual Machine (VM) occurrence which is then allocated to the users. The users are charged based on an on-demand model, and their payments should be strong-minded by taking into account both their incentives and the incentives of the cloud providers. These provisions of cloud services make a service market, where users can dynamically pick services based on such attractive norm as price and class. A perceptive model of a service market is a reverse auction. In the first price auction, however, a service that is cheaper and provides better quality is not necessarily selected. Auction markets can incarcerate such incentives, where users name their own prices for their requested VMs. This causes unwanted outcomes both for users and cloud providers. We intend an auction-based online mechanism for VM provisioning, share, and pricing in clouds that deem several types of resources. Our proposed online mechanism makes no theory about future demand of VMs, which is the case in real cloud settings. The proposed online mechanism is summoned as soon as a user places a request or some of the allocated resources are released and become available. The mechanism assigns VM instances to selected users for the period they are requested for, and ensures that the users will continue using their VM instances for the entire requested period. In addition, the mechanism determines the payment the users have to pay for using the assigned resources. We prove that the mechanism is incentive-compatible, that is, it gives incentives to the users to reveal their actual requests. We investigate the performance of our proposed mechanism through extensive experiments.