Fix tests for the containers we're running them in

hostname1/dbus_test.go

@@ -61,7 +61,7 @@ func TestStaticHostname(t *testing.T) {
 	if err != nil && err != io.EOF {
 		t.Fatal(err)
 	}
-	// Close the file so that systemd-hostnamed can use it.
+	// Close the file so that hostnamed can use it.
 	hostnameFile.Close()
 	expectedHostname := strings.TrimSuffix(string(expectedHostnameBytes[:n]), "\n")
 
@@ -75,44 +75,33 @@ func TestStaticHostname(t *testing.T) {
 	} else if hostname != expectedHostname {
 		t.Fatalf("expected %q, got %q", expectedHostname, hostname)
 	}
-}
-
-func TestSetStaticHostname(t *testing.T) {
-	hostnameFile, err := os.Open("/etc/hostname")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer hostnameFile.Close()
-
-	originalHostnameBytes := make([]byte, 256)
-	n, err := hostnameFile.Read(originalHostnameBytes)
-	if err != nil && err != io.EOF {
-		t.Fatal(err)
-	}
-	// Close the file so that systemd-hostnamed can use it.
-	hostnameFile.Close()
-	originalHostname := strings.TrimSuffix(string(originalHostnameBytes[:n]), "\n")
 
+	// hostnamed replaces the /etc/hostname entirely when the SetStaticHostname
+	// D-Bus method is called.
+	// This doesn't work with container bind mounts, so let's modify the file directly and
+	// see if the StaticHostname property changes.
 	var randomBytes [5]byte
 	if _, err := rand.Read(randomBytes[:]); err != nil {
 		t.Fatal(err)
 	}
 	randomHostname := "newhostname" + hex.EncodeToString(randomBytes[:])
 
-	h, err := New()
+	hostnameFile, err = os.OpenFile("/etc/hostname", os.O_WRONLY|os.O_TRUNC, 0644)
 	if err != nil {
 		t.Fatal(err)
 	}
-
-	if err := h.SetStaticHostname(randomHostname, false); err != nil {
-		t.Fatal(err)
-	}
+	defer hostnameFile.Close()
+	// Restore the original hostname.
 	defer func() {
-		if err := h.SetStaticHostname(string(originalHostname), false); err != nil {
+		if _, err := hostnameFile.WriteString(expectedHostname); err != nil {
 			t.Fatal(err)
 		}
 	}()
 
+	if _, err := hostnameFile.WriteString(randomHostname); err != nil {
+		t.Fatal(err)
+	}
+
 	if hostname, err := h.StaticHostname(); err != nil {
 		t.Fatal(err)
 	} else if hostname != randomHostname {