Add support for extending admin api in go plugins

[ealogar]

Summary

It would be nice that you can implement an extension to the administration api in go, similarly as you may do with a LUA plugin (e.g. defining an api.go and implementing a custom interface).

[p0pr0ck5]

Can I ask, why you would want to do this? Admin API endpoint functionality generally revolves around talking to the datastore, for which there is already extensive functionality in Kong via Lua.

[ealogar]

You develop a complex functionality in go that it's not easy to do in LUA, normally there are many libraries in go but LUA lacks of this...
If it were possible to extend admin-api with this code it would bre great... don't you think ?

[p0pr0ck5]

Yes I understand what you're saying. :) Can you provide specific examples of where using Go to extend the Admin API would be useful?

[ealogar]

I have implemented a go plugin to decrypt JWE tokens. There is not any library in LUA for doing this, but in go you find a go-jose implementation that makes easy to decrypt the tokens.
If I could call this code from an admin-endpoint "/decrypt-token", I could also offer an admin endpoint for inspecting the tokens... as the tokens are encrypted I dont want to offer an api to access them and it's more natural in the admin-api
This is just an example, but you can think in many others.