zones: Env: allow multiple gateways on a Zone

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

pkg/zones/env.go

@@ -38,7 +38,7 @@ func (m *Env) Zones() []int {
 func (m *Env) WriteTo(w io.Writer) (int64, error) {
 	var buf bytes.Buffer
 
-	m.writeEnvVar(&buf, genEnvInts(m.Zones()), "ZONES")
+	m.writeEnvVarInts(&buf, m.Zones(), "ZONES")
 	m.ForEachZone(func(z *Zone) bool {
 		m.writeEnvZone(&buf, z)
 		return false
@@ -57,10 +57,22 @@ func (m *Env) writeEnvZone(w io.Writer, z *Zone) {
 	m.writeEnvVar(w, z.Name, "ZONE%v_%s", zoneID, "NAME")
 
 	// ZONE{zoneID}_GW
-	gateways := z.GatewayIDs()
-	if len(gateways) > 0 {
-		m.writeEnvVar(w, genEnvInts(gateways), "ZONE%v_%s", zoneID, "GW")
+	gateways, _ := z.GatewayIDs()
+	m.writeEnvVarInts(w, gateways, "ZONE%v_%s", zoneID, "GW")
+}
+
+func (m *Env) writeEnvVarInts(w io.Writer, value []int, name string, args ...any) {
+	var s string
+
+	if n := len(value); n > 0 {
+		ss := make([]string, len(value))
+		for i, v := range value {
+			ss[i] = fmt.Sprintf("%v", v)
+		}
+		s = strings.Join(ss, " ")
 	}
+
+	m.writeEnvVar(w, s, name, args...)
 }
 
 func (m *Env) writeEnvVar(w io.Writer, value string, name string, args ...any) {
@@ -81,15 +93,6 @@ func (m *Env) writeEnvVar(w io.Writer, value string, name string, args ...any) {
 	}
 }
 
-func genEnvInts(a []int) string {
-	s := make([]string, len(a))
-	for i, id := range a {
-		s[i] = fmt.Sprintf("%v", id)
-	}
-
-	return strings.Join(s, " ")
-}
-
 func genEnvZoneNodes(z *Zone) string {
 	if n := z.Len(); n > 0 {
 		s := make([]string, 0, n)