update upstreams to format ipv6 adddress for nginx plus (#2339)

Problem: Users want to have IPv6 upstreams correctly formatted when using NGINX Plus with NGF.

Solution: Adds a fix to update IP format based on endpoint type.

Author: salonichf5

internal/mode/static/nginx/config/convert.go

@@ -18,8 +18,13 @@ func ConvertEndpoints(eps []resolver.Endpoint) []ngxclient.UpstreamServer {
 			port = fmt.Sprintf(":%d", ep.Port)
 		}
 
+		format := "%s%s"
+		if ep.IPv6 {
+			format = "[%s]%s"
+		}
+
 		server := ngxclient.UpstreamServer{
-			Server: fmt.Sprintf("%s%s", ep.Address, port),
+			Server: fmt.Sprintf(format, ep.Address, port),
 		}
 
 		servers = append(servers, server)

internal/mode/static/nginx/config/convert_test.go

@@ -19,6 +19,11 @@ func TestConvertEndpoints(t *testing.T) {
 			Address: "5.6.7.8",
 			Port:    0,
 		},
+		{
+			Address: "2001:db8::1",
+			Port:    443,
+			IPv6:    true,
+		},
 	}
 
 	expUpstreams := []ngxclient.UpstreamServer{
@@ -28,6 +33,9 @@ func TestConvertEndpoints(t *testing.T) {
 		{
 			Server: "5.6.7.8",
 		},
+		{
+			Server: "[2001:db8::1]:443",
+		},
 	}
 
 	g := NewWithT(t)