I would suggest to add those 2 features:

1)
Right now, you can just add an Domain with ACME or with a Custom Certificate.
When beeing behind an SSL-Terminating Reverse-Proxy (like in K8s) no Cert is needed at all.
How to solve: 3rd Option: Add Domain without Cert

2)
MELI_MONGO_URI should be generated using a bash script inside the container.

In addition we should use the ENV VARs, eg.:

MELI_MONGO_USER
MELI_MONGO_PASSWORD
MELI_MONGO_HOST
MELI_MONGO_PORT
MELI_MONGO_DB

The second change is not mandatory, but would make the K8s config easier, also a Secret could be used to inject the Password.