some comments, package comments

plugin/plugin.go

@@ -0,0 +1,10 @@
+// The plugin package exposes functions and helpers for communicating to
+// Terraform plugins which are implemented as standalone binary applications.
+//
+// plugin.Client fully manages the lifecycle of executing the application,
+// connecting to it, and returning the RPC client and service names for
+// connecting to it using the terraform/rpc package.
+//
+// plugin.Serve fully manages listeners to expose an RPC server from a binary
+// that plugin.Client can connect to.
+package plugin

rpc/resource_provider.go

@@ -6,6 +6,8 @@ import (
 	"github.com/hashicorp/terraform/terraform"
 )
 
+// ResourceProvider is an implementation of terraform.ResourceProvider
+// that communicates over RPC.
 type ResourceProvider struct {
 	Client *rpc.Client
 	Name   string
@@ -24,6 +26,8 @@ func (p *ResourceProvider) Configure(c map[string]interface{}) ([]string, error)
 	return resp.Warnings, err
 }
 
+// ResourceProviderServer is a net/rpc compatible structure for serving
+// a ResourceProvider. This should not be used directly.
 type ResourceProviderServer struct {
 	Provider terraform.ResourceProvider
 }