You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: docker_validator.go
    path of file: ./repos/kubeedge/vendor/k8s.io/system-validators/validators
    
    the code of the file until where you have to start completion: /*
Copyright 2016 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package system

import (
	"bytes"
	"encoding/json"
	"os/exec"
	"regexp"
	"strings"

	"github.com/pkg/errors"
)

var _ Validator = &DockerValidator{}

// DockerValidator validates docker configuration.
type DockerValidator struct {
	Reporter Reporter
}

// dockerInfo holds a local subset of the Info struct from
// https://github.com/docker/cli/blob/master/cli/command/system/info.go
// and https://github.com/moby/moby/blob/master/api/types/types.go
// The JSON output from 'docker info' should map to this struct.
type dockerInfo struct {
	Driver        string   `json:"Driver"`
	ServerVersion string   `json:"ServerVersion"`
	ServerErrors  []string `json:",omitempty"`
}

// Name is part of the system.Validator interface.
func (d *DockerValidator) Name() string {
	return "docker"
}

const (
	dockerConfigPrefix           = "DOCKER_"
	latestValidatedDockerVers
    
func (d *DockerValidator) validateDockerInfo(spec *DockerSpec, info dockerInfo) ([]error, []error) {
	// Validate docker version.
	if info.ServerErrors != nil {
		return nil, []error{errors.Errorf("error verifying Docker info: %q", strings.Join(info.ServerErrors, `", "`))}
	}

	matched := false
	for _, v := range spec.Version {
		r := regexp.MustCompile(v)
		if r.MatchString(info.ServerVersion) {
			d.Reporter.Report(dockerConfigPrefix+"VERSION", info.ServerVersion, good)
			matched = true
		}
	}
	if !matched {
		// If it's of the new Docker version scheme but didn't match above, it
		// must be a newer version than the most recently validated one.
		ver := `\d{2}\.\d+\.\d+(?:-[a-z]{2})?`
		r := regexp.MustCompile(ver)
		if r.MatchString(info.ServerVersion) {
			d.Reporter.Report(dockerConfigPrefix+"VERSION", info.ServerVersion, good)
			w := errors.Errorf(
				"this Docker version is not on the list of validated versions: %s. Latest validated version: %s",
				info.ServerVersion,
				latestValidatedDockerVersion,
			)
			return []error{w}, nil
		}
		d.Reporter.Report(dockerConfigPrefix+"VERSION", info.ServerVersion, bad)
		return nil, []error{errors.Errorf("unsupported docker version: %s", info.ServerVersion)}
	}
	// Validate graph driver.
	item := dockerConfigPrefix + "GRAPH_DRIVER"
	for _, gd := range spec.GraphDriver {
		if info.Driver == gd {
			d.Reporter.Report(item, info.Driver, good)
			return nil, nil
		}
	}
	d.Reporter.Report(item, info.Driver, bad)
	return nil, []error{errors.Errorf("unsupported graph driver: %s", info.Driver)}
}