Which is the maximum number of source service accounts permitted per firewall rule?

In Google Cloud, each firewall rule can have a maximum of 10 source service accounts defined. This limitation is put in place to manage complexity and maintain performance in the networking environment. By allowing up to 10 source service accounts, users can implement targeted security policies that apply to a specific set of instances or services without creating overly complicated rules or exceeding manageable limits. Effective use of service accounts helps enforce the principle of least privilege, ensuring that only authorized identities have specified network access.

This framing not only aids in security but also in compliance with various regulatory requirements that suggest granular access controls. The choice of 10 as the maximum is designed to strike a balance between flexibility and manageability.