Add method to get the IP address a port is bound to (#95)

Signed-off-by: Colin Edwards <colin@recursivepenguin.com>

dockertest.go

@@ -42,6 +42,23 @@ func (r *Resource) GetPort(id string) string {
 	return m[0].HostPort
 }
 
+func (r *Resource) GetBoundIP(id string) string {
+	if r.Container == nil {
+		return ""
+	} else if r.Container.NetworkSettings == nil {
+		return ""
+	}
+
+	m, ok := r.Container.NetworkSettings.Ports[dc.Port(id)]
+	if !ok {
+		return ""
+	} else if len(m) == 0 {
+		return ""
+	}
+
+	return m[0].HostIP
+}
+
 // NewTLSPool creates a new pool given an endpoint and the certificate path. This is required for endpoints that
 // require TLS communication.
 func NewTLSPool(endpoint, certpath string) (*Pool, error) {

dockertest_test.go

@@ -47,6 +47,8 @@ func TestPostgres(t *testing.T) {
 	require.Nil(t, err)
 	assert.NotEmpty(t, resource.GetPort("5432/tcp"))
 
+	assert.NotEmpty(t, resource.GetBoundIP("5432/tcp"))
+
 	err = pool.Retry(func() error {
 		db, err := sql.Open("postgres", fmt.Sprintf("postgres://postgres:secret@localhost:%s/postgres?sslmode=disable", resource.GetPort("5432/tcp")))
 		if err != nil {