Initial upgrade flow for control-plane

clitools/pkg/controller/osimage/helpers.go

@@ -1,5 +1,20 @@
 package osimage
 
+import (
+	"fmt"
+	"os"
+	"strings"
+	"sync"
+
+	monov1alpha1 "example.com/monok8s/pkg/apis/monok8s/v1alpha1"
+)
+
+var (
+	bootStateOnce sync.Once
+	bootState     map[string]string
+	bootStateErr  error
+)
+
 func PercentOf(done, total int64) int64 {
 	if total <= 0 {
 		return 0
@@ -13,3 +28,34 @@ func PercentOf(done, total int64) int64 {
 	}
 	return p
 }
+
+func ReadBootState() (map[string]string, error) {
+	bootStateOnce.Do(func() {
+		data, err := os.ReadFile(monov1alpha1.BootStateFile)
+		if err != nil {
+			bootStateErr = err
+			return
+		}
+
+		out := make(map[string]string)
+
+		for _, line := range strings.Split(string(data), "\n") {
+			line = strings.TrimSpace(line)
+			if line == "" || strings.HasPrefix(line, "#") {
+				continue
+			}
+
+			k, v, ok := strings.Cut(line, "=")
+			if !ok {
+				bootStateErr = fmt.Errorf("invalid line: %q", line)
+				return
+			}
+
+			out[strings.TrimSpace(k)] = strings.TrimSpace(v)
+		}
+
+		bootState = out
+	})
+
+	return bootState, bootStateErr
+}