From 13b96d758446e8eca7aa9fcc9a1de8877d693b8a Mon Sep 17 00:00:00 2001
From: Yossi Boaron <yossi.boaron.1234@gmail.com>
Date: Sun, 9 Feb 2020 14:47:39 +0200
Subject: [PATCH] Consider mdns hostname file existence in utils.ShortHostname

The utils.ShortHostname function should read hostname from mdns
hostname (/etc/mdns/hostname), if mdns hostname file exists.

The mdns hostname file being handled by [1] MCO PR.

[1] https://github.com/openshift/machine-config-operator/pull/1446
---
 pkg/utils/utils.go | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/pkg/utils/utils.go b/pkg/utils/utils.go
index 6cfd3c12..6de9e298 100644
--- a/pkg/utils/utils.go
+++ b/pkg/utils/utils.go
@@ -8,8 +8,12 @@ import (
 	"net/http"
 	"os"
 	"strings"
+
+	"github.com/sirupsen/logrus"
 )
 
+var log = logrus.New()
+
 func FletcherChecksum8(inp string) uint8 {
 	var ckA, ckB uint8
 	for i := 0; i < len(inp); i++ {
@@ -20,9 +24,29 @@ func FletcherChecksum8(inp string) uint8 {
 }
 
 func ShortHostname() (shortName string, err error) {
-	hostname, err := os.Hostname()
-	if err != nil {
-		panic(err)
+	var hostname string
+
+	if filePath, ok := os.LookupEnv("RUNTIMECFG_HOSTNAME_PATH"); ok {
+		dat, err := ioutil.ReadFile(filePath)
+		if err != nil {
+			log.WithFields(logrus.Fields{
+				"filePath": filePath,
+			}).Error("Failed to read file")
+			return "", err
+		}
+		hostname = strings.TrimSuffix(string(dat), "\n")
+		log.WithFields(logrus.Fields{
+			"hostname": hostname,
+			"file":     filePath,
+		}).Debug("Hostname retrieved from a file")
+	} else {
+		hostname, err = os.Hostname()
+		if err != nil {
+			panic(err)
+		}
+		log.WithFields(logrus.Fields{
+			"hostname": hostname,
+		}).Debug("Hostname retrieved from OS")
 	}
 	splitHostname := strings.SplitN(hostname, ".", 2)
 	shortName = splitHostname[0]