1 diff --git a/morph.go b/morph.go
2 index a88414b..e5894df 100644
5 @@ -542,6 +542,7 @@ func getNixContext() *nix.NixContext {
6 return &nix.NixContext{
7 EvalMachines: filepath.Join(assetRoot, assets.Friendly, "eval-machines.nix"),
10 KeepGCRoot: *keepGCRoot,
11 AllowBuildShell: *allowBuildShell,
13 @@ -574,8 +575,10 @@ func buildHosts(hosts []nix.Host) (resultPath string, err error) {
17 - fmt.Fprintln(os.Stderr, "nix result path: ")
18 - fmt.Println(resultPath)
19 + if resultPath != "" {
20 + fmt.Fprintln(os.Stderr, "nix result path: ")
21 + fmt.Println(resultPath)
26 diff --git a/nix/nix.go b/nix/nix.go
27 index 6a9cfd5..0f7884b 100644
30 @@ -49,6 +49,7 @@ type Deployment struct {
31 type NixContext struct {
38 @@ -269,6 +270,10 @@ func (ctx *NixContext) BuildMachines(deploymentPath string, hosts []Host, nixArg
39 args = append(args, "--show-trace")
43 + args = append(args, "--dry-run")
46 if nixBuildTargets != "" {
48 "--arg", "buildTargets", nixBuildTargets)
49 @@ -308,6 +313,10 @@ func (ctx *NixContext) BuildMachines(deploymentPath string, hosts []Host, nixArg
50 return resultPath, errors.New(errorMessage)
57 resultPath, err = os.Readlink(resultLinkPath)