# Functions
NewExternalSigningServer creates and runs a new ExternalSigningServer which uses the given rootCA to sign node certificates.
NewTestCA is a helper method that creates a TestCA and a bunch of default connections and security configs.
# Variables
External controls whether or not NewTestCA() will create a TestCA server configured to use an external signer or not.
# Structs
ExternalSigningServer runs an HTTPS server with an endpoint at a specified URL which signs node certificate requests from a swarm manager client.
TestCA is a structure that encapsulates everything needed to test a CA Server.