enable proxying requests to a book sync service

[jduar]

This enables proxying requests to a book sync service like Grimmory, basically allowing me to run both Readeckobo for Readeck articles through Instapaper and Grimmory with which I sync books and reading progress.

I found readeckobo a few days ago and was going to set it up only to realize it used the same api_endpoint Grimmory and other book services already use. It would probably be a lot of work adding article functionality to those, so I thought of modifying Readeckobo to proxy requests it doesn't handle to Grimmory instad of the Kobo store. So I tested my theory and it works! With this I can have both article and book sync from two different services.

I tried to keep the changes as minimal as possible while keeping the mechanism generic so it supports the many book services like Grimmory, Komga, Calibre Web, etc. My understanding is that these all sync books pretty much the same way with slightly different endpoints.

I've only actually tested this against Grimmory though and have it running fine in my Kobo. I also tried making the configuration steps as clear as possible but feel free to suggest any changes.

[eleith]

pretty sweet. i didn't think about doing that inside of readeckobo itself!

i've been handling this at the reverse proxy layer instead.

i'll give this PR a study to better understand the implementation and tradeoffs. i am interested.

thank you!

[jduar]

Looking at your snippet, it does look like a simpler solution actually - I wish I'd thought of it before 😅

Right now I'm undecided which is the best approach under my "in one year when I completely forget how I set these up will I understand what's happening?" rule.