Optionally set defaults file when minting images.

We want to ensure that static defaults are set when images run within
particular environments, e.g., a particular GCE project. This occurs
when there exists a file in `/etc/defaults/cuttlefish-integration` and
contains `static_defaults_when=<condition>` (see #1859). We thus need to
ensure that the `cuttlefish-integration` file is set appropriately; we
just do this by uploading the file when minting the image.

Author: 3405691582

tools/baseimage/cmd/gce_install_cuttlefish_packages/main.go

@@ -29,8 +29,9 @@ import (
 )
 
 const (
-	outImageName = "amended-image"
-	mountpoint   = "/mnt/image"
+	outImageName                      = "amended-image"
+	mountpoint                        = "/mnt/image"
+	defaultsCuttlefishIntegrationFile = "/etc/defaults/cuttlefish-integration"
 )
 
 type DebSrcsFlag struct {
@@ -53,11 +54,12 @@ func (v *DebSrcsFlag) Set(s string) error {
 }
 
 var (
-	project              = flag.String("project", "", "GCP project whose resources will be used for creating the amended image")
-	zone                 = flag.String("zone", "us-central1-a", "GCP zone used for creating relevant resources")
-	source_image_project = flag.String("source-image-project", "", "Source image GCP project")
-	source_image         = flag.String("source-image", "", "Source image name")
-	deb_srcs             = DebSrcsFlag{}
+	project                             = flag.String("project", "", "GCP project whose resources will be used for creating the amended image")
+	zone                                = flag.String("zone", "us-central1-a", "GCP zone used for creating relevant resources")
+	source_image_project                = flag.String("source-image-project", "", "Source image GCP project")
+	source_image                        = flag.String("source-image", "", "Source image name")
+	deb_srcs                            = DebSrcsFlag{}
+	defaults_cuttlefish_integration_src = flag.String("defaults_cuttlefish_integration_src", "", "Path to file which will be written to /etc/defaults/cuttlefish-integration.")
 )
 
 func init() {
@@ -111,6 +113,16 @@ func installCuttlefishDebs(project, zone, insName string, debSrcs []string) erro
 	return nil
 }
 
+func maybeSetDefaultsCuttlefishIntegrationFile(project, zone, insName string) error {
+	if *defaults_cuttlefish_integration_src != "" {
+		// The disk mountpoint is at /mnt/image, mounted in `installCuttlefishDebs`, and is not unmounted.
+		if err := gce.UploadFile(project, zone, insName, *defaults_cuttlefish_integration_src, mountpoint+defaultsCuttlefishIntegrationFile); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 func cleanupDeleteDisk(h *gce.GceHelper, disk string) {
 	log.Printf("cleanup: deleting disk %q...", disk)
 	if err := h.DeleteDisk(disk); err != nil {
@@ -191,6 +203,10 @@ func amendImageMain(project, zone string, opts amendImageOpts) error {
 		return fmt.Errorf("install cuttlefish debs error: %v", err)
 	}
 
+	if err := maybeSetDefaultsCuttlefishIntegrationFile(project, zone, insName); err != nil {
+		return fmt.Errorf("couldn't set %s: %v", defaultsCuttlefishIntegrationFile, err)
+	}
+
 	// Reboot the instance to force a clean umount of the attached disk's file system.
 	if err := gce.RunCmd(project, zone, insName, "sudo reboot"); err != nil {
 		return err