func ErrorConnectionFailed(host string) error {
	return fmt.Errorf("Cannot connect to the Docker daemon at %s. Is the docker daemon running?", host)
}
ErrorConnectionFailed returns an error with host in the error message when connection to docker daemon failed.
package client
import (
	"errors"
	"fmt"
)
var ErrConnectionFailed = errors.New("Cannot connect to the Docker daemon. Is the docker daemon running on this host?")