Long plan results in: socket: too many open files

I am using http.Client for my provider and create a single instance in the providerConfigure method. I then reuse that single instance for all of my underlying REST API calls. However, when I have a very long plan, I get:

socket: too many open files

Any advice on this? I am new to GoLang, so not sure if I am not closing something I should be or whatever.

Looks like I forgot to close my response body on every call.