Fix issues with Nameservers (#258)

Co-authored-by: Robert Hoppe <[email protected]>

stackit/internal/resources/network/actions.go

@@ -58,7 +58,7 @@ func (r Resource) createNetwork(ctx context.Context, resp *resource.CreateRespon
 			continue
 		}
 
-		ns = append(ns, nsVal)
+		ns = appendIfMissting(ns, nsVal)
 	}
 
 	// ensure we have the Nameservers sorted
@@ -152,8 +152,8 @@ func (r Resource) Read(ctx context.Context, req resource.ReadRequest, resp *reso
 	}
 
 	// ensure we have the nameservers sorted
-
 	nameservers := make([]attr.Value, 0)
+
 	if n.Nameservers != nil && len(*n.Nameservers) > 0 {
 		nsData := *n.Nameservers
 		sort.Strings(nsData)
@@ -243,9 +243,12 @@ func (r Resource) updateNetwork(ctx context.Context, plan, state Network, resp *
 			continue
 		}
 
-		ns = append(ns, s.String())
+		ns = appendIfMissting(ns, s.String())
 	}
 
+	// ensure we have the Nameservers sorted
+	sort.Strings(ns)
+
 	name := plan.Name.ValueString()
 
 	body := iaas_network.V1UpdateNetworkJSONBody{
@@ -327,3 +330,13 @@ func (r *Resource) ImportState(ctx context.Context, req resource.ImportStateRequ
 	resp.Diagnostics.Append(resp.State.SetAttribute(ctx, path.Root("project_id"), projectID)...)
 	resp.Diagnostics.Append(resp.State.SetAttribute(ctx, path.Root("id"), networkID)...)
 }
+
+func appendIfMissting(valueList []string, value string) []string {
+	for _, v := range valueList {
+		if v == value {
+			return valueList
+		}
+	}
+
+	return append(valueList, value)
+}