gcloud SQL postgres - FATAL: remaining connection slots are reserved for non-replication superuser connections

Update: now you can set the max_connections setting via Cloud SQL Flags. See https://cloud.google.com/sql/docs/postgres/flags#postgres-m

This was my answer in the time of writing the question:

There is currently no way to increase a limit, but we are aware of this problem. Please follow Issue 37271935 on our issue tracker.