I would like to automate the lookup table, create data adapter, etc. configurations.
I do not want to create it manually using the GUI on the browser but instead using ansible or some other automation tools. I would like to know which files for graylog needs to be changed so that I write a script based on that.
Rest API browser is a nice tool to try, but still I would suggest rather use Developer Tools in browser. Simple open Developer Tools switch to tab Network and XHR requests. Then create for example Lookup table in graylog web UI and then pause recording in Developer Tools. Then find POST/PUT request that create new entry and check parameters used to create it. You can also copy complete request to curl using Copy - Copy as cURL (in Firefox).