feat(etcd): Default etcd name to /etc/machine-id

system/systemd.go

@@ -2,6 +2,7 @@ package system
 
 import (
 	"fmt"
+	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -161,3 +162,8 @@ func ExecuteScript(scriptPath string) (string, error) {
 func SetHostname(hostname string) error {
 	return exec.Command("hostnamectl", "set-hostname", hostname).Run()
 }
+
+func MachineID(root string) string {
+	contents, _ := ioutil.ReadFile(path.Join(root, "etc", "machine-id"))
+	return strings.TrimSpace(string(contents))
+}

system/systemd_test.go

@@ -100,3 +100,17 @@ Where=/media/state
 	}
 }
 
+func TestMachineID(t *testing.T) {
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer syscall.Rmdir(dir)
+
+	os.Mkdir(path.Join(dir, "etc"), os.FileMode(0755))
+	ioutil.WriteFile(path.Join(dir, "etc", "machine-id"), []byte("node007\n"), os.FileMode(0444))
+
+	if MachineID(dir) != "node007" {
+		t.Fatalf("File has incorrect contents")
+	}
+}