| 312f5e43 |
// GetContextFromReader will read the contents of the given reader as either a
// Dockerfile or tar archive. Returns a tar archive used as a context and a
// path to the Dockerfile inside the tar.
func GetContextFromReader(r io.ReadCloser, dockerfileName string) (out io.ReadCloser, relDockerfile string, err error) {
buf := bufio.NewReader(r)
magic, err := buf.Peek(archive.HeaderSize)
if err != nil && err != io.EOF {
return nil, "", fmt.Errorf("failed to peek context header from STDIN: %v", err)
}
if archive.IsArchive(magic) {
return ioutils.NewReadCloserWrapper(buf, func() error { return r.Close() }), dockerfileName, nil
}
// Input should be read as a Dockerfile.
tmpDir, err := ioutil.TempDir("", "docker-build-context-")
if err != nil {
return nil, "", fmt.Errorf("unbale to create temporary context directory: %v", err)
}
f, err := os.Create(filepath.Join(tmpDir, DefaultDockerfileName))
if err != nil {
return nil, "", err
}
_, err = io.Copy(f, buf)
if err != nil {
f.Close()
return nil, "", err
}
if err := f.Close(); err != nil {
return nil, "", err
}
if err := r.Close(); err != nil {
return nil, "", err
}
tar, err := archive.Tar(tmpDir, archive.Uncompressed)
if err != nil {
return nil, "", err
}
return ioutils.NewReadCloserWrapper(tar, func() error {
err := tar.Close()
os.RemoveAll(tmpDir)
return err
}), DefaultDockerfileName, nil
}
// GetContextFromGitURL uses a Git URL as context for a `docker build`. The
// git repo is cloned into a temporary directory used as the context directory.
// Returns the absolute path to the temporary context directory, the relative
// path of the dockerfile in that context directory, and a non-nil error on
// success.
func GetContextFromGitURL(gitURL, dockerfileName string) (absContextDir, relDockerfile string, err error) {
if _, err := exec.LookPath("git"); err != nil {
return "", "", fmt.Errorf("unable to find 'git': %v", err)
}
if absContextDir, err = gitutils.Clone(gitURL); err != nil {
return "", "", fmt.Errorf("unable to 'git clone' to temporary context directory: %v", err)
}
return getDockerfileRelPath(absContextDir, dockerfileName)
}
// GetContextFromURL uses a remote URL as context for a `docker build`. The
// remote resource is downloaded as either a Dockerfile or a tar archive.
// Returns the tar archive used for the context and a path of the
// dockerfile inside the tar.
func GetContextFromURL(out io.Writer, remoteURL, dockerfileName string) (io.ReadCloser, string, error) {
response, err := httputils.Download(remoteURL)
if err != nil {
return nil, "", fmt.Errorf("unable to download remote context %s: %v", remoteURL, err)
}
progressOutput := streamformatter.NewStreamFormatter().NewProgressOutput(out, true)
// Pass the response body through a progress reader.
progReader := progress.NewProgressReader(response.Body, progressOutput, response.ContentLength, "", fmt.Sprintf("Downloading build context from remote url: %s", remoteURL))
return GetContextFromReader(ioutils.NewReadCloserWrapper(progReader, func() error { return response.Body.Close() }), dockerfileName)
}
// GetContextFromLocalDir uses the given local directory as context for a
// `docker build`. Returns the absolute path to the local context directory,
// the relative path of the dockerfile in that context directory, and a non-nil
// error on success.
func GetContextFromLocalDir(localDir, dockerfileName string) (absContextDir, relDockerfile string, err error) {
// When using a local context directory, when the Dockerfile is specified
// with the `-f/--file` option then it is considered relative to the
// current directory and not the context directory.
if dockerfileName != "" {
if dockerfileName, err = filepath.Abs(dockerfileName); err != nil {
return "", "", fmt.Errorf("unable to get absolute path to Dockerfile: %v", err)
}
}
return getDockerfileRelPath(localDir, dockerfileName)
}
// getDockerfileRelPath uses the given context directory for a `docker build`
// and returns the absolute path to the context directory, the relative path of
// the dockerfile in that context directory, and a non-nil error on success.
func getDockerfileRelPath(givenContextDir, givenDockerfile string) (absContextDir, relDockerfile string, err error) {
if absContextDir, err = filepath.Abs(givenContextDir); err != nil {
return "", "", fmt.Errorf("unable to get absolute context directory: %v", err)
}
// The context dir might be a symbolic link, so follow it to the actual
// target directory.
//
// FIXME. We use isUNC (always false on non-Windows platforms) to workaround
// an issue in golang. On Windows, EvalSymLinks does not work on UNC file
// paths (those starting with \\). This hack means that when using links
// on UNC paths, they will not be followed.
if !isUNC(absContextDir) {
absContextDir, err = filepath.EvalSymlinks(absContextDir)
if err != nil {
return "", "", fmt.Errorf("unable to evaluate symlinks in context path: %v", err)
}
}
stat, err := os.Lstat(absContextDir)
if err != nil {
return "", "", fmt.Errorf("unable to stat context directory %q: %v", absContextDir, err)
}
if !stat.IsDir() {
return "", "", fmt.Errorf("context must be a directory: %s", absContextDir)
}
absDockerfile := givenDockerfile
if absDockerfile == "" {
// No -f/--file was specified so use the default relative to the
// context directory.
absDockerfile = filepath.Join(absContextDir, DefaultDockerfileName)
// Just to be nice ;-) look for 'dockerfile' too but only
// use it if we found it, otherwise ignore this check
if _, err = os.Lstat(absDockerfile); os.IsNotExist(err) {
altPath := filepath.Join(absContextDir, strings.ToLower(DefaultDockerfileName))
if _, err = os.Lstat(altPath); err == nil {
absDockerfile = altPath
}
}
}
// If not already an absolute path, the Dockerfile path should be joined to
// the base directory.
if !filepath.IsAbs(absDockerfile) {
absDockerfile = filepath.Join(absContextDir, absDockerfile)
}
// Evaluate symlinks in the path to the Dockerfile too.
//
// FIXME. We use isUNC (always false on non-Windows platforms) to workaround
// an issue in golang. On Windows, EvalSymLinks does not work on UNC file
// paths (those starting with \\). This hack means that when using links
// on UNC paths, they will not be followed.
if !isUNC(absDockerfile) {
absDockerfile, err = filepath.EvalSymlinks(absDockerfile)
if err != nil {
return "", "", fmt.Errorf("unable to evaluate symlinks in Dockerfile path: %v", err)
}
}
if _, err := os.Lstat(absDockerfile); err != nil {
if os.IsNotExist(err) {
return "", "", fmt.Errorf("Cannot locate Dockerfile: %q", absDockerfile)
}
return "", "", fmt.Errorf("unable to stat Dockerfile: %v", err)
}
if relDockerfile, err = filepath.Rel(absContextDir, absDockerfile); err != nil {
return "", "", fmt.Errorf("unable to get relative Dockerfile path: %v", err)
}
if strings.HasPrefix(relDockerfile, ".."+string(filepath.Separator)) {
return "", "", fmt.Errorf("The Dockerfile (%s) must be within the build context (%s)", givenDockerfile, givenContextDir)
}
return absContextDir, relDockerfile, nil
}
// isUNC returns true if the path is UNC (one starting \\). It always returns
// false on Linux.
func isUNC(path string) bool {
return runtime.GOOS == "windows" && strings.HasPrefix(path, `\\`)
} |