What configuration must be made to ensure App Engine can connect to Memorystore?

To enable App Engine to connect to Memorystore effectively, configuring the VPC Access Connector within the same region is essential. This configuration allows App Engine to privately connect to resources that are hosted within a Virtual Private Cloud (VPC) network, such as a Memorystore Redis instance.

Using a VPC Access Connector enables App Engine to access the Memorystore without exposing it to the public internet, thus maintaining the application's security and performance. Both App Engine and Memorystore must exist in the same region to ensure optimal latency and connectivity. By setting up the VPC Access Connector in this manner, you facilitate a robust and secure connection between these services.

The other alternatives do not provide the necessary requirements for connectivity. Using a public IP address for Memorystore compromises security by exposing the instance to the public internet. Removing all firewall rules could lead to the unintended blocking of necessary traffic, which would result in connectivity issues. Implementing private connectivity settings is indeed a component of ensuring secure access, but it does not replace the need for a correctly configured VPC Access Connector for this particular use case.