The README should caution users against careless instantiation of the client

[orivej]

As explained in consulapi#1499 and go-dockerclient#434, it is not safe at all to replace http.DefaultClient with &http.Client{} or cleanhttp.DefaultClient(), and the README should address this fairly obscure and dangerous issue. I think it should suggest library authors to either instantiate a global DefaultClient, or to set DisableKeepAlives to true.

[jefferai]

Using a global default client negates the point of this library, which is to ensure that you are using a clean client that will not be modified willy-nilly by other parts of an application. What you're suggesting is simply a different use-case than this library is designed for.

[orivej]

cleanhttp.DefaultClient() can not replace http.DefaultClient due to unbound growth of the number of established connections of many cleanhttp.DefaultClient()s in the connection pools of their http transports, and per-library global default client as in hashicorp/consul#1517 currently is the best use of this library.

[jefferai]

Let's keep the discussion going at fsouza/go-dockerclient#434