It seems you are using the Bitnami Docker image for Discourse, which is different from the images that this documentation is referring to (AWS AMIs, see https://bitnami.com/stack/discourse/cloud/aws).
Please note that, unlike cloud images, our Docker images don't contain all the services needed to run the application, e.g. the database. The Docker approach is to run each of them in different containers. In the case of Discourse, three different containers are needed:
You need to configure each container to work together using environment variables, please check the bitnami-docker-discourse GitHub page for more details.
Also, you can use the
[docker-compose.yml](https://github.com/bitnami/bitnami-docker-discourse/blob/master/2/debian-9/docker-compose.yml) file that should work out of the box running