Add hot reload collections

[chorng]

I am serving data with stac-fastapi-geoparquet with a pipeline regularly adds new items to existing parquets and updates the extent of collections.json stored remotely. Since collection.json is load only once when the app starts, we have to restart the service every time after the collection.json is updated.

This is a draft which implements a mechanism to reload and cache collections.json at a set time interval, and all requests will go through the latest cached collection.json. With the hot reload mechanism the updated collections.json can be reflected without restarting the service.

@gadomski What do you think having a hot reload mechanism at the backend? Please let me know if this feature fits to the project, thank you!

[gadomski]

Thanks for this! I haven't had time to look at it yet, but just dropping a note to say I've seen it an it's in the queue. I'm not against the idea of hot-reloading on principal, but I'll want to take a think to see if there's any alternatives.

[gadomski]

It makes sense, but what about something simpler -- just add a new API endpoint that tells the lambda to reload the collection file? If you're worried about other people hitting it you could put it behind auth. E.g. POST /collections/reload?

[vincentsarago]

+1 on creating a function to list and store the collections in the state https://github.com/developmentseed/tipg/blob/47e1f091ecd8e8962808753e891e9bb0d6947c31/tipg/main.py#L40-L41

[gadomski]

If you wanted to keep things auto-magic, tipg has an example that doesn't rely on globals: https://github.com/developmentseed/tipg/blob/47e1f091ecd8e8962808753e891e9bb0d6947c31/tipg/middleware.py#L73-L118

[chorng]

Thank you for reviewing. Will try to implement sth similar to tipg as suggested :)

[chorng]

Removed globals and implemented a TTL middleware.

[gadomski]

This looks good, thank you, and thanks for your patience.