refactor(systemd): don't allow users to set DropIn=true yet

initialize/config_test.go

@@ -162,6 +162,26 @@ func TestCloudConfigSerializationHeader(t *testing.T) {
 	}
 }
 
+// TestDropInIgnored asserts that users are unable to set DropIn=True on units
+func TestDropInIgnored(t *testing.T) {
+	contents := `
+coreos:
+  units:
+    - name: test
+      dropin: true
+`
+	cfg, err := NewCloudConfig(contents)
+	if err != nil || len(cfg.Coreos.Units) != 1 {
+		t.Fatalf("Encountered unexpected error: %v", err)
+	}
+	if len(cfg.Coreos.Units) != 1 || cfg.Coreos.Units[0].Name != "test" {
+		t.Fatalf("Expected 1 unit, but got %d: %v", len(cfg.Coreos.Units), cfg.Coreos.Units)
+	}
+	if cfg.Coreos.Units[0].DropIn {
+		t.Errorf("dropin option on unit in cloud-config was not ignored!")
+	}
+}
+
 func TestCloudConfigUsers(t *testing.T) {
 	contents := `
 users:

system/systemd.go

@@ -27,7 +27,11 @@ type Unit struct {
 	Runtime bool
 	Content string
 	Command string
-	DropIn  bool // drop-in configuration? if so, a cloudinit.conf will be generated
+
+	// For drop-in units, a cloudinit.conf is generated.
+	// This is currently unbound in YAML (and hence unsettable in cloud-config files)
+	// until the correct behaviour for multiple drop-in units is determined.
+	DropIn bool `yaml:"-"`
 }
 
 func (u *Unit) Type() string {