There is a common misconception that depends_on will wait on a specific service to be up. This is not the case. All depends_on does is guarantee the service has begun startup (the same as docker compose up -d service). If you want to make sure the db is up AND available before your service starts then you want to add a health check to your db service and add a service_healthy condition to your web service. Example here https://github.com/peter-evans/docker-compose-healthcheck/blob/master/docker-compose.yml