Remove bootstrap, download images on-demand

images.go

@@ -0,0 +1,82 @@
+// Copyright 2019 Mikhail Klementev. All rights reserved.
+// Use of this source code is governed by a AGPLv3 license
+// (or later) that can be found in the LICENSE file.
+
+package main
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"os/exec"
+)
+
+// inspired by Edd Turtle code
+func downloadFile(filepath string, url string) (err error) {
+	out, err := os.Create(filepath)
+	if err != nil {
+		return
+	}
+	defer out.Close()
+
+	resp, err := http.Get(url)
+	if err != nil {
+		return
+	}
+	defer resp.Body.Close()
+
+	switch resp.StatusCode {
+	case http.StatusOK:
+		break
+	case http.StatusForbidden, http.StatusNotFound:
+		err = fmt.Errorf("Cannot download %s. It looks like you need "+
+			"to generate it manually and place it "+
+			"to ~/.out-of-tree/images/. "+
+			"Check documentation for additional information.", url)
+		return
+	default:
+		err = fmt.Errorf("Something weird happens while "+
+			"download file: %d", resp.StatusCode)
+		return
+	}
+
+	_, err = io.Copy(out, resp.Body)
+	return
+}
+
+func unpackTar(archive, destination string) (err error) {
+	// NOTE: If you're change anything in tar command please check also
+	// BSD tar (or if you're using macOS, do not forget to check GNU Tar)
+	// Also make sure that sparse files are extracting correctly
+	cmd := exec.Command("tar", "-Sxf", archive)
+	cmd.Dir = destination + "/"
+
+	rawOutput, err := cmd.CombinedOutput()
+	if err != nil {
+		err = fmt.Errorf("%v: %s", err, rawOutput)
+		return
+	}
+
+	return
+}
+
+func downloadImage(path, file string) (err error) {
+	tmp, err := ioutil.TempDir("/tmp/", "out-of-tree_")
+	if err != nil {
+		return
+	}
+	defer os.RemoveAll(tmp)
+
+	archive := tmp + "/" + file + ".tar.gz"
+	url := imagesBaseURL + file + ".tar.gz"
+
+	err = downloadFile(archive, url)
+	if err != nil {
+		return
+	}
+
+	err = unpackTar(archive, path)
+	return
+}