Adding `depends_on` only waits for container being ready (docker internal stuff).
Even when the containers ready, they're likely crashed due to external dependencies, i.e. oxAuth needs entries in LDAP.
For your info, we designed Gluu containers to have a safe sequence of startup orders for various deployment scenarios, from custom scripts, docker compose, k8s manifests, etc. I would recommend you to follow our Gluu containers design. In other words, applying custom startup orders (i.e. wait-for-it script) need deeper knowledge of our design and docker container in general.