Since version 4.2, MongoDB provides a new interesting feature called Externally Sourced Configuration File Values. It allows administrators to specify that particular variables will have their values loaded from an external resource. The external resources that are supported, at this time, are: REST APIs, which will cause MongoDB to perform HTTP GET requests to a [&]

https://www.percona.com/blog/externally-sourced-configuration-file-values-in-mongodb/