cmd/otk: New otk external: osbuild-make-ostree-source

A new command for otk that creates the org.osbuild.ostree source object
based on the resolved ostree commit data generated from the
osbuild-resolve-ostree-commit command.

cmd/otk/osbuild-make-ostree-source/main.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/osbuild/images/pkg/osbuild"
+	"github.com/osbuild/images/pkg/ostree"
+)
+
+// TODO: move structs to common package with resolver external
+
+type Input struct {
+	Tree InputTree `json:"tree"`
+}
+
+type InputTree struct {
+	Const InputConst `json:"const"`
+}
+
+type InputConst struct {
+	// Ref of the commit (can be empty).
+	Ref string `json:"ref,omitempty"`
+
+	// URL of the repo where the commit can be fetched.
+	URL string `json:"url"`
+
+	// Secrets type to use when pulling the ostree commit content
+	// (e.g. org.osbuild.rhsm.consumer).
+	Secrets string `json:"secrets,omitempty"`
+
+	// Checksum of the commit.
+	Checksum string `json:"checksum"`
+}
+
+type Output struct {
+	OSTreeSource osbuild.OSTreeSource `json:"org.osbuild.ostree"`
+}
+
+func run(r io.Reader, w io.Writer) error {
+	var inp Input
+	if err := json.NewDecoder(r).Decode(&inp); err != nil {
+		return err
+	}
+
+	ostreeSource := osbuild.NewOSTreeSource()
+	ostreeSource.AddItem(ostree.CommitSpec{
+		Ref:      inp.Tree.Const.Ref,
+		URL:      inp.Tree.Const.URL,
+		Secrets:  inp.Tree.Const.Secrets,
+		Checksum: inp.Tree.Const.Checksum,
+	})
+
+	output := Output{
+		OSTreeSource: *ostreeSource,
+	}
+	out := map[string]interface{}{
+		"tree": output,
+	}
+	outputJson, err := json.MarshalIndent(out, "", "  ")
+	if err != nil {
+		return fmt.Errorf("cannot marshal response: %w", err)
+	}
+	fmt.Fprintf(w, "%s\n", outputJson)
+	return nil
+}
+
+func main() {
+	if err := run(os.Stdin, os.Stdout); err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v", err.Error())
+		os.Exit(1)
+	}
+}