Merge branch 'main' of https://github.com/svdavidson/warewulf into svdavidson-main

internal/app/wwctl/configure/hosts/main.go

@@ -7,12 +7,14 @@ import (
 	"github.com/hpcng/warewulf/internal/pkg/wwlog"
 	"github.com/spf13/cobra"
 	"os"
+	"bytes"
 	"text/template"
 )
 
 type TemplateStruct struct {
-	Ipaddr   string
-	Fqdn     string
+	PrevHostFile string
+	Ipaddr       string
+	Fqdn         string
 	AllNodes []node.NodeInfo
 }
 
@@ -42,7 +44,40 @@ func CobraRunE(cmd *cobra.Command, args []string) error {
 		os.Exit(1)
 	}
 
-	w, err := os.OpenFile("/etc/hosts", os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
+	replace.PrevHostFile = ""
+	w, err := os.Open("/etc/hosts")
+	if err != nil {
+		wwlog.Printf(wwlog.WARN, "%s\n", err)
+	} else {
+		// if /etc/hosts.ww does not exist, backup /etc/hosts to /etc/hosts.wwbackup
+		if ! util.IsFile("/etc/hosts.wwbackup") {
+			err = util.CopyFile("/etc/hosts", "/etc/hosts.wwbackup")
+			if err != nil {
+				wwlog.Printf(wwlog.ERROR, "%s\n", err)
+			}
+		}
+
+		// read all lines before the # warewulf comment and put into PrevHostFile template variable
+		lines, _ := util.ReadFile("/etc/hosts")
+		if lines != nil {
+			var buffer bytes.Buffer
+			for _, line := range lines {
+				//wwlog.Printf(wwlog.INFO, "Reading line: %s\n", line)
+				if util.ValidString(line, "^#.*maintained by warewulf") {
+					break
+				}
+				buffer.WriteString(line)
+				buffer.WriteString("\n")
+			}
+			replace.PrevHostFile = buffer.String()
+		}
+	}
+
+	//wwlog.Printf(wwlog.INFO, "PrevHostFile is %s\n", replace.PrevHostFile)
+
+	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)