How to add custom rest api endpoints in cosmos-based chain?

[VegeBun-csj]

Is there an existing issue for this?

• I have searched the existing issues

What happened?

i want to add some customize rest query api in my cosmos-based chain, how to implement it?

Cosmos SDK Version

0.47.5

How to reproduce?

No response

[facundomedica]

If you want to add a query you can add it to your module and that will get exposed in the REST API.
But if what you want is to add extra endpoints, unrelated to the modules and such, you can add it in RegisterAPIRoutes with the mux.Router you find inside apiSvr. A good example would be how RegisterSwaggerAPI does it.

[VegeBun-csj]

@facundomedica Thank you for your explanation. Currently, my situation is as follows: Since my chain has a maximum supply and actual circulating supply, I want to distinguish between them in the future. However, at the moment, the chain itself only provides an API for the total supply and does not have an API for the actual circulating supply. Therefore, I am considering adding a circulating supply API. In this case, would you recommend adding it within the bank module or in the external router? I would appreciate your advice.

[taramakage]

@VegeBun-csj Hope my train of thought is correct: it is likely you want to add a query RPC for x/bank? Directly modifying x/bank would bring some maintenance burden. How about implementing a circulating gRPC query server which relies on the x/bank keeper to access underlying data? Then you only need to register that server to the app's gRPC server.

[VegeBun-csj]

@taramakage thanks for your suggestion. It sounds like it could be feasible. Maybe i need to try it out in practice to see how it works.