Which role is most appropriate to provide a group with the ability to view configuration details of an Azure App Service plan and modify role assignments for a web app?

The Owner role is the most appropriate choice for providing a group with the ability to view configuration details of an Azure App Service plan and modify role assignments for a web app. This role includes full access to all Azure resources, which means that users assigned to this role can not only access and view configuration details but also change role assignments and permissions for others.

In Azure role-based access control (RBAC), the Owner role is designed to encompass all capabilities available within a subscription or resource group. This includes the authority to manage access permissions, making it ideal for scenarios where delegation of responsibilities, including modifying roles, is necessary. Thus, assigning the Owner role ensures comprehensive control over both the app service plan's configuration and the ability to manage assignments for those working on the web app.

Other roles, such as Contributor, Web Plan Contributor, or Website Contributor, do not possess the same level of authority. The Contributor role allows for creating and managing resources, but it does not include permissions to manage access or view role assignments. Similarly, Web Plan Contributor and Website Contributor may provide permissions specific to web services, but they lack the comprehensive capabilities to modify user roles and permissions necessary for managing configuration details and access control effectively.