cluster: introduce Region.Cluster and m/{region}/k8s_token

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/cluster/regions.go

@@ -16,6 +16,7 @@ type Region struct {
 	zones []*Zone
 
 	Name    string
+	Cluster *string  `json:",omitempty" yaml:",omitempty"`
 	Regions []string `json:",omitempty" yaml:",omitempty"`
 }
 
@@ -106,6 +107,26 @@ func (m *Cluster) setRegionZones(name string, zones ...*Zone) {
 	})
 }
 
+func (m *Cluster) setRegionClusterToken(name string, token string) error {
+	for i := range m.Regions {
+		r := &m.Regions[i]
+
+		if r.Name == name {
+			// found
+			r.Cluster = &token
+			return nil
+		}
+	}
+
+	// new
+	m.Regions = append(m.Regions, Region{
+		m:       m,
+		Name:    name,
+		Cluster: &token,
+	})
+	return nil
+}
+
 func (m *Cluster) appendRegionRegions(name string, subs ...string) {
 	for i := range m.Regions {
 		r := &m.Regions[i]
@@ -210,9 +231,25 @@ func (z *Zone) syncZoneRegions() error {
 // SyncRegions writes to the file system the regions covered
 // by this meta-region
 func (r *Region) SyncRegions() error {
+	if err := r.syncRegionsFile(); err != nil {
+		return err
+	}
+
+	return r.syncClusterFile()
+}
+
+func (r *Region) mkdir() error {
+	return r.m.MkdirAll(r.Name)
+}
+
+func (r *Region) syncRegionsFile() error {
+	var err error
+
 	name := filepath.Join(r.Name, ZoneRegionsFileName)
 
-	if len(r.Regions) > 0 {
+	if len(r.Regions) == 0 {
+		err = r.m.RemoveFile(name)
+	} else if err = r.mkdir(); err == nil {
 		var buf bytes.Buffer
 
 		for _, s := range r.Regions {
@@ -220,12 +257,29 @@ func (r *Region) SyncRegions() error {
 			_, _ = buf.WriteRune('\n')
 		}
 
-		if err := r.m.MkdirAll(r.Name); err != nil {
-			return err
-		}
-
-		return r.m.WriteStringFile(buf.String(), name)
+		err = r.m.WriteStringFile(buf.String(), name)
 	}
 
-	return r.m.RemoveFile(name)
+	return err
+}
+
+func (r *Region) syncClusterFile() error {
+	var err error
+
+	name := filepath.Join(r.Name, RegionClusterTokenFileName)
+
+	if r.Cluster == nil {
+		err = r.m.RemoveFile(name)
+	} else if err = r.mkdir(); err == nil {
+		var buf bytes.Buffer
+
+		_, _ = buf.WriteString(*r.Cluster)
+		if buf.Len() > 0 {
+			_, _ = buf.WriteRune('\n')
+		}
+
+		err = r.m.WriteStringFile(buf.String(), name)
+	}
+
+	return err
 }