sources/fedora-http: Unpack Fedora from ISO

Signed-off-by: Din Music <[email protected]>

sources/fedora-http.go

@@ -1,6 +1,7 @@
 package sources
 
 import (
+	"crypto/sha256"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -10,49 +11,87 @@ import (
 	"path/filepath"
 	"regexp"
 	"sort"
+	"strconv"
+	"strings"
 
 	"github.com/canonical/lxd-imagebuilder/shared"
 )
 
 type fedora struct {
-	common
+	commonRHEL
 }
 
 // Run downloads a container base image and unpacks it and its layers.
 func (s *fedora) Run() error {
-	baseURL := fmt.Sprintf("%s/packages/Fedora-Container-Base", s.definition.Source.URL)
+	// For backwards compatibility, fallback to manual URL construction
+	// when the release version is equal or less than 40.
+	relNum, err := strconv.Atoi(s.definition.Image.Release)
+	if err == nil && relNum <= 40 {
+		baseURL := fmt.Sprintf("%s/packages/Fedora-Container-Base", s.definition.Source.URL)
+
+		// Get latest build
+		build, err := s.getLatestBuild(baseURL, s.definition.Image.Release)
+		if err != nil {
+			return fmt.Errorf("Failed to get latest build: %w", err)
+		}
 
-	// Get latest build
-	build, err := s.getLatestBuild(baseURL, s.definition.Image.Release)
-	if err != nil {
-		return fmt.Errorf("Failed to get latest build: %w", err)
+		fname := fmt.Sprintf("Fedora-Container-Base-%s-%s.%s.tar.xz", s.definition.Image.Release, build, s.definition.Image.ArchitectureMapped)
+
+		// Download image
+		sourceURL := fmt.Sprintf("%s/%s/%s/images/%s", baseURL, s.definition.Image.Release, build, fname)
+
+		fpath, err := s.DownloadHash(s.definition.Image, sourceURL, "", nil)
+		if err != nil {
+			return fmt.Errorf("Failed to download %q: %w", sourceURL, err)
+		}
+
+		s.logger.WithField("file", filepath.Join(fpath, fname)).Info("Unpacking image")
+
+		// Unpack the base image
+		err = shared.Unpack(filepath.Join(fpath, fname), s.rootfsDir)
+		if err != nil {
+			return fmt.Errorf("Failed to unpack %q: %w", filepath.Join(fpath, fname), err)
+		}
+
+		s.logger.Info("Unpacking layers")
+
+		// Unpack the rest of the image (/bin, /sbin, /usr, etc.)
+		err = s.unpackLayers(s.rootfsDir)
+		if err != nil {
+			return fmt.Errorf("Failed to unpack: %w", err)
+		}
+
+		return nil
 	}
 
-	fname := fmt.Sprintf("Fedora-Container-Base-%s-%s.%s.tar.xz",
-		s.definition.Image.Release, build, s.definition.Image.ArchitectureMapped)
+	// Otherwise, get the ISO image URL from the available releases.
+	sourceURL, checksum, err := s.getDownloadURL(s.definition.Image.Release, s.definition.Image.Variant, s.definition.Image.ArchitectureMapped, ".iso")
+	if err != nil {
+		return err
+	}
 
-	// Download image
-	sourceURL := fmt.Sprintf("%s/%s/%s/images/%s", baseURL, s.definition.Image.Release, build, fname)
+	if checksum == "" {
+		return fmt.Errorf("Checksum not found for %q", sourceURL)
+	}
 
 	fpath, err := s.DownloadHash(s.definition.Image, sourceURL, "", nil)
 	if err != nil {
 		return fmt.Errorf("Failed to download %q: %w", sourceURL, err)
 	}
 
-	s.logger.WithField("file", filepath.Join(fpath, fname)).Info("Unpacking image")
+	fname := filepath.Join(fpath, filepath.Base(sourceURL))
 
-	// Unpack the base image
-	err = shared.Unpack(filepath.Join(fpath, fname), s.rootfsDir)
+	err = shared.VerifyChecksum(fpath, checksum, sha256.New())
 	if err != nil {
-		return fmt.Errorf("Failed to unpack %q: %w", filepath.Join(fpath, fname), err)
+		return fmt.Errorf("Failed to verify checksum: %w", err)
 	}
 
-	s.logger.Info("Unpacking layers")
+	s.logger.WithField("file", fname).Info("Unpacking image")
 
-	// Unpack the rest of the image (/bin, /sbin, /usr, etc.)
-	err = s.unpackLayers(s.rootfsDir)
+	// Unpack the base image
+	err = s.unpackISO(fname, s.rootfsDir, s.isoRunner)
 	if err != nil {
-		return fmt.Errorf("Failed to unpack: %w", err)
+		return fmt.Errorf("Failed to unpack %q: %w", fname, err)
 	}
 
 	return nil
@@ -174,3 +213,124 @@ func (s *fedora) getLatestBuild(URL string, release string) (string, error) {
 	// Return latest build
 	return matches[len(matches)-1], nil
 }
+
+// getDownloadURL fetches JSON representation of current releases and
+// extracts the download URL matching the given release, variant, arch,
+// and filetype (.tar.xz, .iso, etc.).
+func (s *fedora) getDownloadURL(release string, variant string, arch string, fileType string) (url string, checksum string, err error) {
+	releasesURL := "https://fedoraproject.org/releases.json"
+	s.logger.Infof("Querying %q for list of available releases", releasesURL)
+
+	// Fetch available releases.
+	resp, err := http.Get(releasesURL)
+	if err != nil {
+		return "", "", fmt.Errorf("Failed to fetch releases from %q: %w", releasesURL, err)
+	}
+
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", "", fmt.Errorf("Unexpected status code %q from %q: %w", resp.StatusCode, releasesURL, err)
+	}
+
+	// Parse JSON response.
+	var result []struct {
+		Release    string `json:"version"`
+		Arch       string `json:"arch"`
+		Variant    string `json:"variant"`
+		Subvariant string `json:"subvariant"`
+		URL        string `json:"link"`
+		SHA256     string `json:"sha256"`
+		SizeBytes  string `json:"size"`
+	}
+
+	err = json.NewDecoder(resp.Body).Decode(&result)
+	if err != nil {
+		return "", "", fmt.Errorf("Failed to parse JSON response: %w", err)
+	}
+
+	// Variant mapping.
+	// Default to variant "Container" and subvariant "Container_Base".
+	var subvariant string
+	if variant == "default" || variant == "cloud" {
+		variant = "Server"
+		subvariant = "Server"
+	}
+
+	// Iterate over response items and find the matching image.
+	for _, item := range result {
+		if item.Release != release || item.Arch != arch || item.Variant != variant {
+			continue
+		}
+
+		if subvariant != "" && item.Subvariant != subvariant {
+			continue
+		}
+
+		if !strings.HasSuffix(item.URL, fileType) {
+			continue
+		}
+
+		// Matching URL found.
+		return item.URL, item.SHA256, nil
+	}
+
+	return "", "", fmt.Errorf("Failed to find download URL for release %q, variant %q, arch %q, and file type %q", release, variant, arch, fileType)
+}
+
+func (s *fedora) isoRunner(gpgkeys string) error {
+	err := shared.RunScript(s.ctx, fmt.Sprintf(`#!/bin/sh
+set -eux
+
+# Create required files
+touch /etc/mtab /etc/fstab
+
+dnf_args=""
+mkdir -p /etc/yum.repos.d
+
+# Add cdrom repo
+cat <<- EOF > /etc/yum.repos.d/cdrom.repo
+[cdrom]
+name=Install CD-ROM
+baseurl=file:///mnt/cdrom
+enabled=0
+EOF
+
+GPG_KEYS="%s"
+
+gpg_keys_official="file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-%[2]s-primary"
+
+if [ -n "${GPG_KEYS}" ]; then
+	echo gpgcheck=1 >> /etc/yum.repos.d/cdrom.repo
+	echo gpgkey=${gpg_keys_official} ${GPG_KEYS} >> /etc/yum.repos.d/cdrom.repo
+else
+	echo gpgcheck=0 >> /etc/yum.repos.d/cdrom.repo
+fi
+
+dnf_args="--disablerepo=* --enablerepo=cdrom"
+
+# Newest install.img doesnt have rpm installed,
+# so first install rpm.
+if ! command -v rpmkeys; then
+	cd /mnt/cdrom/Packages
+	dnf ${dnf_args} -y install rpm
+fi
+
+pkgs="basesystem fedora-release dnf"
+
+# Create a minimal rootfs
+mkdir /rootfs
+dnf ${dnf_args} --installroot=/rootfs --releasever=%[2]s -y install ${pkgs}
+rm -rf /rootfs/var/cache/yum
+rm -rf /rootfs/var/cache/dnf
+rm -rf /etc/yum.repos.d/cdrom.repo
+# Remove all files in mnt packages
+rm -rf /mnt/cdrom
+`, gpgkeys, s.definition.Image.Release))
+
+	if err != nil {
+		return fmt.Errorf("Failed to run script: %w", err)
+	}
+
+	return nil
+}