- Added support for JoinInfo so that driver can override certain

container config.
- Added JoinOption processing for extra /etc/hosts record.
- Added support for updating /etc/hosts entries of other containers.
- Added sandbox support for adding a sandbox without the OS level create.

Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>

driverapi/driverapi.go

@@ -44,7 +44,7 @@ type Driver interface {
 	EndpointInfo(nid, eid types.UUID) (map[string]interface{}, error)
 
 	// Join method is invoked when a Sandbox is attached to an endpoint.
-	Join(nid, eid types.UUID, sboxKey string, options map[string]interface{}) error
+	Join(nid, eid types.UUID, sboxKey string, options map[string]interface{}) (*JoinInfo, error)
 
 	// Leave method is invoked when a Sandbox detaches from an endpoint.
 	Leave(nid, eid types.UUID, options map[string]interface{}) error
@@ -52,3 +52,11 @@ type Driver interface {
 	// Type returns the the type of this driver, the network type this driver manages
 	Type() string
 }
+
+// JoinInfo represents a set of resources that the driver has the ability to provide during
+// join time.
+type JoinInfo struct {
+	SandboxKey      string
+	NoSandboxCreate bool
+	HostsPath       string
+}