What is the name of this CDN/Caching pattern, and what is the least-effort solution?

I am new to web dev (but I have >20 years experience with C++/C# dev). I feel like this is such an obvious pattern that it must have a) a name and b) an off-the-shelf implementation I can just use, but I'm not turning up anything obvious with extensive googling.

The behaviour that I want to have is the following. On an incoming URL request for an MP4 file, check if the requested media exists in persistent storage.

1. If the media already exists, just serve it.
2. If the media does not exist, spin up an expensive and heavy JS stack to dynamically render the media, store result to persistent storage, and serve the result.

Two complicating factors:

• I want to be able to trigger a re-render of the media if necessary (for example if the source data or compression params change)
• I want to ensure that parallel requests for cache-miss media (case 2.) do not trigger parallel render jobs.

What's the name of this design pattern, and what is the least-effort solution?

I already have a working Google Cloud Function prototype for the "spin up expensive and heavy JS stack and render the media" part, but I'm not sure how to implement the rest. Will I need a database of some kind to keep track of render operations and thus avoid parallel redundant render jobs?