Harness enhances the deployment of Azure Resource Manager (ARM) templates by introducing variables for templatization, which simplifies the management of microservices and offers rollback support, a feature absent in Azure. This approach allows for scalable infrastructure management by using a single parameter file for different microservices, reducing the complexity of maintaining multiple files. Harness variables, such as Service, Environment, Secret, and Workflow, are resolved before ARM deployment requests, enabling efficient template management. Additionally, Harness provides rollback support by saving the current state of the Resource Group before changes are made, allowing a return to the previous state if a deployment fails. This rollback mechanism is accomplished by deploying the existing template in COMPLETE mode, ensuring that only the specified resources remain.