cmd: add new build command

This commit adds the `build` command. It takes the same flags as
`manifest` and will build the specified image.

cmd/image-builder/build.go

@@ -0,0 +1,24 @@
+package main
+
+import (
+	"fmt"
+	"path/filepath"
+
+	"github.com/osbuild/images/pkg/imagefilter"
+	"github.com/osbuild/images/pkg/osbuild"
+)
+
+func buildImage(res *imagefilter.Result, osbuildManifest []byte) error {
+	osbuildStoreDir := ".store"
+	// XXX: support output dir via commandline
+	// XXX2: support output filename via commandline (c.f.
+	//   https://github.com/osbuild/images/pull/1039)
+	outputDir := "."
+	buildName := fmt.Sprintf("%s-%s-%s", res.Distro.Name(), res.ImgType.Name(), res.Arch.Name())
+	jobOutputDir := filepath.Join(outputDir, buildName)
+
+	// XXX: support stremaing via images/pkg/osbuild/monitor.go
+	_, err := osbuild.RunOSBuild(osbuildManifest, osbuildStoreDir, jobOutputDir, res.ImgType.Exports(), nil, nil, false, osStderr)
+	return err
+
+}