The best option for ensuring continued operations until the microservice is fixed is to add a HTTP liveness probe to the microservice's deployment. A HTTP liveness probe is a type of probe that checks if a Pod is alive by sending an HTTP request and expecting a success response code. If the probe fails, Kubernetes will restart the Pod. You can add a HTTP liveness probe to your microservice's deployment by using a livenessProbe field in your Pod spec. This way, you can ensure that any Pod that returns 403 errors after running for more than five hours will be restarted automatically and resume normal operations.

The best option for optimizing your cloud spend by ensuring that only a single instance of your infrastructure stack exists at a time is to confirm that the pipeline is storing and retrieving the terraform.tfstate file from Cloud Storage with the Terraform gcs backend. The terraform.tfstate file is a file that Terraform uses to store the current state of your infrastructure. The Terraform gcs backend is a backend type that allows you to store the terraform.tfstate file in a Cloud Storage bucket. By using the Terraform gcs backend, you can ensure that your pipeline has access to the latest state of your infrastructure and avoid creating multiple copies of the entire infrastructure stack.

https://cloud.google.com/compute/docs/access/service-
accounts#associating_a_service_account_to_an_instance