Logstash input via website user file upload

Hi, Im very new to the whole ELK stack and Im still learning. For my current project Im required to process some MongoDB log files uploaded by user through our website and I have trouble figuring out how I should configure my input at all. For now I managed to use the file input, but only locally and add basic filter function.

My other question is... Could I do this process without running the elasticsearch on the website ? All I need is for logstash to parse my .log file into something I can process slightly better since I plan to be doing data visualization myself.

To answer your second question, there is no requirement to use other parts of the elastic stack. You can use logstash to process a file to a file in another format.

Thank you, that might help a bit:)