Set default BMCS builder image name

Set the default image name to "packer-{{timestamp}}".

builder/oracle/bmcs/config.go

@@ -188,8 +188,13 @@ func NewConfig(raws ...interface{}) (*Config, error) {
 	}
 
 	if c.ImageName == "" {
-		errs = packer.MultiErrorAppend(
-			errs, errors.New("'image_name' must be specified"))
+		name, err := interpolate.Render("packer-{{timestamp}}", nil)
+		if err != nil {
+			errs = packer.MultiErrorAppend(errs,
+				fmt.Errorf("unable to parse image name: %s", err))
+		} else {
+			c.ImageName = name
+		}
 	}
 
 	if errs != nil && len(errs.Errors) > 0 {

builder/oracle/bmcs/config_test.go

@@ -130,10 +130,7 @@ func TestConfig(t *testing.T) {
 
 	// Test the correct errors are produced when required template keys are
 	// omitted.
-	requiredKeys := []string{
-		"availability_domain", "base_image_ocid", "shape",
-		"image_name", "subnet_ocid",
-	}
+	requiredKeys := []string{"availability_domain", "base_image_ocid", "shape", "subnet_ocid"}
 	for _, k := range requiredKeys {
 		t.Run(k+"_required", func(t *testing.T) {
 			raw := testConfig(cfgFile)
@@ -147,6 +144,20 @@ func TestConfig(t *testing.T) {
 		})
 	}
 
+	t.Run("ImageNameDefaultedIfEmpty", func(t *testing.T) {
+		raw := testConfig(cfgFile)
+		delete(raw, "image_name")
+
+		c, errs := NewConfig(raw)
+		if errs != nil {
+			t.Errorf("Unexpected error(s): %s", errs)
+		}
+
+		if !strings.Contains(c.ImageName, "packer-") {
+			t.Errorf("got default ImageName %q, want image name 'packer-{{timestamp}}'", c.ImageName)
+		}
+	})
+
 	// Test that AccessCfgFile properties are overridden by their
 	// corosponding template keys.
 	accessOverrides := map[string]string{