From d1f80662a66c6bb38dec59a053d339e60a617890 Mon Sep 17 00:00:00 2001
From: Niko Kivel <niko.kivel@psi.ch>
Date: Thu, 28 Jan 2021 11:41:12 +0100
Subject: [PATCH] Fix configure hosts show emptying /etc/hosts and setpersist
 CLI variable in configure hosts

- Only open `/etc/hosts` when write intended
- Correct `SetPersist` CLI variable
---
 internal/app/wwctl/configure/hosts/main.go | 15 ++++++++-------
 internal/app/wwctl/configure/hosts/root.go |  2 +-
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/internal/app/wwctl/configure/hosts/main.go b/internal/app/wwctl/configure/hosts/main.go
index 2f8e4c6f..bde5159f 100644
--- a/internal/app/wwctl/configure/hosts/main.go
+++ b/internal/app/wwctl/configure/hosts/main.go
@@ -83,13 +83,6 @@ func CobraRunE(cmd *cobra.Command, args []string) error {
 
 	w.Close()
 
-	w, err = os.OpenFile("/etc/hosts", os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
-	if err != nil {
-		wwlog.Printf(wwlog.ERROR, "%s\n", err)
-		os.Exit(1)
-	}
-	defer w.Close()
-
 	nodes, _ := n.FindAllNodes()
 
 	replace.AllNodes = nodes
@@ -97,6 +90,14 @@ func CobraRunE(cmd *cobra.Command, args []string) error {
 	replace.Fqdn = controller.Fqdn
 
 	if SetShow == false {
+		// only open "/etc/hosts" when intended to write, as 'os.O_TRUNC' will empty the file otherwise.
+		w, err = os.OpenFile("/etc/hosts", os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
+		if err != nil {
+			wwlog.Printf(wwlog.ERROR, "%s\n", err)
+			os.Exit(1)
+		}
+		defer w.Close()
+
 		err = tmpl.Execute(w, replace)
 		if err != nil {
 			wwlog.Printf(wwlog.ERROR, "%s\n", err)
diff --git a/internal/app/wwctl/configure/hosts/root.go b/internal/app/wwctl/configure/hosts/root.go
index 5be05e85..958bf57d 100644
--- a/internal/app/wwctl/configure/hosts/root.go
+++ b/internal/app/wwctl/configure/hosts/root.go
@@ -16,7 +16,7 @@ var (
 
 func init() {
 	baseCmd.PersistentFlags().BoolVarP(&SetShow, "show", "s", false, "Show configuration (don't update)")
-	baseCmd.PersistentFlags().BoolVar(&SetShow, "persist", false, "Persist the configuration and initialize the service")
+	baseCmd.PersistentFlags().BoolVar(&SetPersist, "persist", false, "Persist the configuration and initialize the service")
 }
 
 // GetRootCommand returns the root cobra.Command for the application.