From f62fbae0cc439744aa70d4c0017e1012a83c74cb Mon Sep 17 00:00:00 2001
From: Stefan Majer <stefan.majer@f-i-ts.de>
Date: Tue, 2 Apr 2024 16:29:34 +0200
Subject: [PATCH] Nicer etcd ismounted handling

---
 go.mod  |  1 +
 go.sum  |  2 ++
 main.go | 26 +++++++++++++++++---------
 3 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/go.mod b/go.mod
index 18af35f..17cb5d8 100644
--- a/go.mod
+++ b/go.mod
@@ -17,6 +17,7 @@ require (
 	github.com/metal-stack/v v1.0.3
 	// archiver must stay in version v2.1.0, see replace below
 	github.com/mholt/archiver v3.1.1+incompatible
+	github.com/moby/sys/mountinfo v0.7.1
 	github.com/pierrec/lz4/v4 v4.1.21
 	github.com/prometheus/common v0.51.1
 	github.com/samber/slog-loki/v3 v3.2.2
diff --git a/go.sum b/go.sum
index dccafb4..e721ce6 100644
--- a/go.sum
+++ b/go.sum
@@ -957,6 +957,8 @@ github.com/moby/spdystream v0.2.0/go.mod h1:f7i0iNDQJ059oMTcWxx8MA/zKFIuD/lY+0Gq
 github.com/moby/sys/mountinfo v0.4.0/go.mod h1:rEr8tzG/lsIZHBtN/JjGG+LMYx9eXgW2JI+6q0qou+A=
 github.com/moby/sys/mountinfo v0.4.1/go.mod h1:rEr8tzG/lsIZHBtN/JjGG+LMYx9eXgW2JI+6q0qou+A=
 github.com/moby/sys/mountinfo v0.5.0/go.mod h1:3bMD3Rg+zkqx8MRYPi7Pyb0Ie97QEBmdxbhnCLlSvSU=
+github.com/moby/sys/mountinfo v0.7.1 h1:/tTvQaSJRr2FshkhXiIpux6fQ2Zvc4j7tAhMTStAG2g=
+github.com/moby/sys/mountinfo v0.7.1/go.mod h1:IJb6JQeOklcdMU9F5xQ8ZALD+CUr5VlGpwtX+VE0rpI=
 github.com/moby/sys/signal v0.6.0/go.mod h1:GQ6ObYZfqacOwTtlXvcmh9A26dVRul/hbOZn88Kg8Tg=
 github.com/moby/sys/symlink v0.1.0/go.mod h1:GGDODQmbFOjFsXvfLVn3+ZRxkch54RkSiGqsZeMYowQ=
 github.com/moby/sys/symlink v0.2.0/go.mod h1:7uZVF2dqJjG/NsClqul95CqKOBRQyYSNnJ6BMgR/gFs=
diff --git a/main.go b/main.go
index 6c36f8e..3a76aa2 100644
--- a/main.go
+++ b/main.go
@@ -15,31 +15,39 @@ import (
 	"github.com/metal-stack/metal-hammer/cmd/event"
 	"github.com/metal-stack/metal-hammer/cmd/network"
 	"github.com/metal-stack/metal-hammer/pkg/kernel"
+	"github.com/moby/sys/mountinfo"
 )
 
 func main() {
+	jsonHandler := slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
+		Level: slog.LevelDebug,
+	})
+	log := slog.New(jsonHandler)
+
 	fmt.Print(cmd.HammerBanner)
 	if len(os.Args) > 1 {
 		panic("cmd args are not supported")
 	}
 
-	err := syscall.Unmount("/etc", syscall.MNT_FORCE)
+	mounted, err := mountinfo.Mounted("/etc")
 	if err != nil {
-		fmt.Printf("unable to umount /etc, which is overmounted with tmpfs %s", err)
-		// os.Exit(1) // FIXME enable again
+		log.Error("unable to check if /etc is a mountpoint", "error", err)
+		os.Exit(1)
+	}
+	if mounted {
+		err := syscall.Unmount("/etc", syscall.MNT_FORCE)
+		if err != nil {
+			log.Error("unable to umount /etc, which is overmounted with tmpfs", "error", err)
+			os.Exit(1)
+		}
 	}
 
 	err = updateResolvConf()
 	if err != nil {
-		fmt.Printf("error updating resolv.conf %s", err)
+		log.Error("error updating resolv.conf", "error", err)
 		os.Exit(1)
 	}
 
-	jsonHandler := slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
-		Level: slog.LevelDebug,
-	})
-	log := slog.New(jsonHandler)
-
 	// Reboot if metal-hammer crashes after 60sec.
 	go kernel.Watchdog(log)