Blockchain as a Service for the Internet of Things is an emerging topic in the blockchain research and industrial community, especially relating to increased system consistency, security, and privacy. Blockchains represent highly distributed and autonomous decision-making systems with distributed data and process management. Internet of Things systems share these characteristics, while also bringing the cyber-physical dimension and machine-to-machine interaction concept to the ecosystem of devices and users. Blockchain infrastructure setup and smart contract prototyping are cumbersome tasks. Onboarding an existing system to a blockchain network takes a significant amount of time and manual effort, and incorporating business logic requires a series of complex steps. For IoT systems, these task needs to be carried out having in mind the typical characteristics of such systems: low hardware, storage, and networking capabilities and high node churn and transaction volume. Moreover, these tasks need to be semi to fully automated in terms of workflows that support easy-to-use integration mechanisms for onboarding of diverse IoT infrastructures and on-demand business logic generation. In this paper, we present a Hyperledger Fabric-based Blockchain as a Service for addressing the identified challenges. Specifically, the framework is tailored to answer to specific requirements of IoT systems through three major services: Hyperledger Fabric Infrastructure Configuration Generator, Hyperledger Fabric Chaincode Builder and Hyperledger Fabric Operator Modules.