I am a beginner trying out api for fun.
The problem is, lets say, I want to write a simple windows program with golang to let my friends read and edit one of the sheets saved on my google drive. How can I do this without having them download a credential file?
What I want it to do is simply redirect them to the Oauth Page right away, and if their email address is one recognized by the app it will grant them access to that google sheet.
What i think you need is to integrate your go app with Oauth protocol. More specifically, with the Google provider.
This is mainly 3 steps:
add the oauth client to your application
something like this: https://github.com/golang/oauth2
See their docs on how to do it.
go to google dev documentation and see how to integrate google auth flow into the client: https://developers.google.com/identity/protocols/OAuth2
I'm not sure if google has something more specific for google drive integration and/or go-lang client in particular. Please do some searching.
make the glue code on your go app so that the user can interact with this (the login button (or command, if it is terminal based), error messages, logout, etc)
More questions will appear when you start to do this, however it is a great example to learn Oauth as well.
General guidelines: