prow/cmd/build/controller.go
func injectedSteps(encodedJobSpec string, dc prowjobv1.DecorationConfig, injectedSource bool, toolsMount coreapi.VolumeMount, entries []wrapper.Options) ([]coreapi.Container, *coreapi.Container, *coreapi.Volume, error) {
	gcsVol, gcsMount, gcsOptions := decorate.GCSOptions(dc)

	sidecar, err := decorate.Sidecar(dc.UtilityImages.Sidecar, gcsOptions, gcsMount, logMount, encodedJobSpec, decorate.RequirePassingEntries, entries...)
	if err != nil {
		return nil, nil, nil, fmt.Errorf("inject sidecar: %v", err)
	}

	var cloneLogMount *coreapi.VolumeMount
	if injectedSource {
		cloneLogMount = &logMount
	}
	initUpload, err := decorate.InitUpload(dc.UtilityImages.InitUpload, gcsOptions, gcsMount, cloneLogMount, encodedJobSpec)
	if err != nil {
		return nil, nil, nil, fmt.Errorf("inject initupload: %v", err)
	}

	placer := decorate.PlaceEntrypoint(dc.UtilityImages.Entrypoint, toolsMount)

	return []coreapi.Container{placer, *initUpload}, sidecar, &gcsVol, nil
}
func injectedSteps(encodedJobSpec string, dc prowjobv1.DecorationConfig, injectedSource bool, toolsMount coreapi.VolumeMount, entries []wrapper.Options) ([]coreapi.Container, *coreapi.Container, *coreapi.Volume, error) {
	gcsVol, gcsMount, gcsOptions := decorate.GCSOptions(dc)

	sidecar, err := decorate.Sidecar(dc.UtilityImages.Sidecar, gcsOptions, gcsMount, logMount, encodedJobSpec, decorate.RequirePassingEntries, entries...)
	if err != nil {
		return nil, nil, nil, fmt.Errorf("inject sidecar: %v", err)
	}

	var cloneLogMount *coreapi.VolumeMount
	if injectedSource {
		cloneLogMount = &logMount
	}
	initUpload, err := decorate.InitUpload(dc.UtilityImages.InitUpload, gcsOptions, gcsMount, cloneLogMount, encodedJobSpec)
	if err != nil {
		return nil, nil, nil, fmt.Errorf("inject initupload: %v", err)
	}

	placer := decorate.PlaceEntrypoint(dc.UtilityImages.Entrypoint, toolsMount)

	return []coreapi.Container{placer, *initUpload}, sidecar, &gcsVol, nil
}
// injectedSteps returns initial containers, a final container and an additional volume.