util: add helper to pull containers

Add a helper function to check if a container image exists locally, if not,
copy the image into the local containers-storage.

bib/cmd/bootc-image-builder/main.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 
 	"github.com/osbuild/bootc-image-builder/bib/internal/setup"
+	"github.com/osbuild/bootc-image-builder/bib/internal/util"
 	"github.com/osbuild/images/pkg/arch"
 	"github.com/osbuild/images/pkg/blueprint"
 	"github.com/osbuild/images/pkg/cloud/awscloud"
@@ -101,6 +102,13 @@ func loadConfig(path string) (*BuildConfig, error) {
 }
 
 func makeManifest(c *ManifestConfig, cacheRoot string) (manifest.OSBuildManifest, error) {
+	if !c.Remote {
+		err := util.EnsureContainerIsInStore(c.Imgref)
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	manifest, err := Manifest(c)
 	if err != nil {
 		return nil, err

bib/internal/util/util.go

@@ -26,3 +26,48 @@ func RunCmdSync(cmdName string, args ...string) error {
 	}
 	return nil
 }
+
+func checkContainerImageExists(storageRef string) (bool, error) {
+	cmd := exec.Command("skopeo", "inspect", storageRef)
+	err := cmd.Run()
+	if err != nil {
+		if cmd.ProcessState.ExitCode() == 1 {
+			return false, nil
+		}
+		return false, err
+	}
+	return true, err
+}
+
+func pullContainerImage(imgref, storageRef string) error {
+	return RunCmdSync(
+		"skopeo",
+		"copy",
+		fmt.Sprintf("docker://%s", imgref),
+		storageRef,
+	)
+}
+
+func EnsureContainerIsInStore(imgref string) error {
+	driver := "overlay"
+	graphRoot := "/var/lib/containers/storage"
+	runRoot := "/run/containers/storage"
+	storageImgRef := fmt.Sprintf("containers-storage:[%s@%s+%s]%s", driver, graphRoot, runRoot, imgref)
+
+	exists, err := checkContainerImageExists(storageImgRef)
+	if err != nil {
+		return fmt.Errorf("Failed to check if container is in local store: %v", err)
+	}
+
+	if exists {
+		fmt.Println("Container image exists in local store")
+		return nil
+	}
+
+	err = pullContainerImage(imgref, storageImgRef)
+	if err != nil {
+		return fmt.Errorf("Failed to pull container: %v", err)
+	}
+
+	return nil
+}