client.go

package main

import (
	"bufio"
	"errors"
	"io"
	"net/http"
	"strings"
)

func getDockerfile(imageId string) (io.Reader, string, error) {
	url := ""
	repository := strings.Split(imageId, ":")
	if len(repository) > 1 || strings.Index(imageId, "/") < 0 {
		if strings.Index(imageId, "/") < 0 {
			repository = append(repository, "latest")
		}
		resp, err := http.Get("https://raw.githubusercontent.com/docker-library/official-images/master/library/" + repository[0])
		if err == nil {
			scanner := bufio.NewScanner(resp.Body)
			scanner.Split(bufio.ScanLines)
			for scanner.Scan() {
				image := strings.Split(scanner.Text(), " ")
				if image[0] == repository[1]+":" {
					r := strings.NewReplacer("git://github.com", "https://raw.githubusercontent.com", "@", "/")
					for len(image[1]) == 0 {
						image = append(image[:0],image[1:]...)
					}
					url = r.Replace(image[1])
					if len(image) > 2 {
						url += "/" + image[2] + "/Dockerfile"
					} else {
						url += "/Dockerfile"
					}
				}
			}
			if url == "" {
				return nil, url, errors.New("Failed to fetch " + imageId)
			}
		} else {
			return nil, url, errors.New("Failed to fetch " + imageId)
		}
	} else {
		url = "https://registry.hub.docker.com/u/" + imageId + "/dockerfile/raw"
	}
	resp, err := http.Get(url)
	if err == nil && strings.Index(resp.Header["Content-Type"][0], "text/plain") >= 0 {
		return resp.Body, url, err
	} else {
		return nil, url, errors.New("Failed to fetch " + imageId)
	}
}