https://access.redhat.com/documentation/en-us/red_hat_quay/3.4/html-single/deploy_red_hat_quay_for_proof-of-concept_non-production_purposes/index#determine_the_ip_address_of_the_database_server

The container IP should not be used because it is not necessarily stable. The users should rely on the fact that the postgres container publishes some well-known Postgres TCP ports and bind them to the host machine. As a result Quay should use the Host IP to contact the Postgres database.

The same is true for the Redis container IP.

https://access.redhat.com/documentation/en-us/red_hat_quay/3.4/html-single/deploy_red_hat_quay_for_proof-of-concept_non-production_purposes/index#determine_the_ip_address_of_the_database_server_2