mirror of https://github.com/hashicorp/packer
Mitchell Hashimoto
13 years ago
parent
66faf73799
commit
a0a78b68e8
@ -0,0 +1,186 @@
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package common
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import (
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"bytes"
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"encoding/hex"
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"errors"
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"fmt"
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"hash"
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"io"
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"net/http"
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"net/url"
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"os"
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)
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// DownloadConfig is the configuration given to instantiate a new
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// download instance. Once a configuration is used to instantiate
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// a download client, it must not be modified.
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type DownloadConfig struct {
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// The source URL in the form of a string.
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Url string
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// This is the path to download the file to.
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TargetPath string
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// DownloaderMap maps a schema to a Download.
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DownloaderMap map[string]Downloader
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// If true, this will copy even a local file to the target
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// location. If false, then it will "download" the file by just
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// returning the local path to the file.
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CopyFile bool
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// The hashing implementation to use to checksum the downloaded file.
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Hash hash.Hash
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// The checksum for the downloaded file. The hash implementation configuration
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// for the downloader will be used to verify with this checksum after
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// it is downloaded.
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Checksum []byte
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}
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// A DownloadClient helps download, verify checksums, etc.
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type DownloadClient struct {
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config *DownloadConfig
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downloader Downloader
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}
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// NewDownloadClient returns a new DownloadClient for the given
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// configuration.
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func NewDownloadClient(c *DownloadConfig) *DownloadClient {
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if c.DownloaderMap == nil {
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c.DownloaderMap = map[string]Downloader{
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"http": new(HTTPDownloader),
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}
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}
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return &DownloadClient{config: c}
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}
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// A downloader is responsible for actually taking a remote URL and
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// downloading it.
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type Downloader interface {
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Cancel()
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Download(io.Writer, *url.URL) error
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Progress() uint
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Total() uint
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}
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func (d *DownloadClient) Cancel() {
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// TODO(mitchellh): Implement
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}
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func (d *DownloadClient) Get() (string, error) {
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// If we already have the file and it matches, then just return the target path.
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if verify, _ := d.VerifyChecksum(d.config.TargetPath); verify {
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return d.config.TargetPath, nil
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}
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url, err := url.Parse(d.config.Url)
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if err != nil {
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return "", err
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}
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// Files when we don't copy the file are special cased.
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var finalPath string
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if url.Scheme == "file" && !d.config.CopyFile {
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finalPath = url.Path
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} else {
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var ok bool
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d.downloader, ok = d.config.DownloaderMap[url.Scheme]
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if !ok {
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return "", fmt.Errorf("No downloader for scheme: %s", url.Scheme)
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}
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// Otherwise, download using the downloader.
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f, err := os.Create(d.config.TargetPath)
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if err != nil {
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return "", err
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}
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defer f.Close()
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err = d.downloader.Download(f, url)
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}
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if d.config.Hash != nil {
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var verify bool
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verify, err = d.VerifyChecksum(finalPath)
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if err == nil && !verify {
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err = fmt.Errorf("checksums didn't match expected: %s", hex.EncodeToString(d.config.Checksum))
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}
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}
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return finalPath, err
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}
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// PercentProgress returns the download progress as a percentage.
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func (d *DownloadClient) PercentProgress() uint {
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return uint((float64(d.downloader.Progress()) / float64(d.downloader.Total())) * 100)
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}
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// VerifyChecksum tests that the path matches the checksum for the
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// download.
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func (d *DownloadClient) VerifyChecksum(path string) (bool, error) {
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if d.config.Checksum == nil || d.config.Hash == nil {
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return false, errors.New("Checksum or Hash isn't set on download.")
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}
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f, err := os.Open(path)
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if err != nil {
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return false, err
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}
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defer f.Close()
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d.config.Hash.Reset()
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io.Copy(d.config.Hash, f)
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return bytes.Compare(d.config.Hash.Sum(nil), d.config.Checksum) == 0, nil
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}
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// HTTPDownloader is an implementation of Downloader that downloads
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// files over HTTP.
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type HTTPDownloader struct {
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progress uint
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total uint
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}
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func (*HTTPDownloader) Cancel() {
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// TODO(mitchellh): Implement
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}
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func (d *HTTPDownloader) Download(dst io.Writer, src *url.URL) error {
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resp, err := http.Get(src.String())
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if err != nil {
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return err
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}
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d.progress = 0
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d.total = uint(resp.ContentLength)
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var buffer [4096]byte
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for {
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n, err := resp.Body.Read(buffer[:])
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if err != nil && err != io.EOF {
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return err
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}
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d.progress += uint(n)
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if _, werr := dst.Write(buffer[:n]); werr != nil {
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return werr
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}
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if err == io.EOF {
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break
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}
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}
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return nil
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}
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func (d *HTTPDownloader) Progress() uint {
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return d.progress
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}
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func (d *HTTPDownloader) Total() uint {
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return d.total
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}
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@ -0,0 +1,42 @@
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package common
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import (
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"crypto/md5"
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"encoding/hex"
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"io/ioutil"
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"os"
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"testing"
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)
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func TestDownloadClient_VerifyChecksum(t *testing.T) {
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tf, err := ioutil.TempFile("", "packer")
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if err != nil {
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t.Fatalf("tempfile error: %s", err)
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}
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defer os.Remove(tf.Name())
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// "foo"
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checksum, err := hex.DecodeString("acbd18db4cc2f85cedef654fccc4a4d8")
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if err != nil {
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t.Fatalf("decode err: %s", err)
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}
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// Write the file
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tf.Write([]byte("foo"))
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tf.Close()
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config := &DownloadConfig{
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Hash: md5.New(),
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Checksum: checksum,
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}
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d := NewDownloadClient(config)
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result, err := d.VerifyChecksum(tf.Name())
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if err != nil {
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t.Fatalf("Verify err: %s", err)
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}
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if !result {
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t.Fatal("didn't verify")
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}
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}
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