Add DefaultGRPCPort and use it in DNSTargetDiscoverer.

Author: jmalloc

CHANGELOG.md

@@ -9,13 +9,24 @@ The format is based on [Keep a Changelog], and this project adheres to
 [Keep a Changelog]: https://keepachangelog.com/en/1.0.0/
 [Semantic Versioning]: https://semver.org/spec/v2.0.0.html
 
+## [0.1.1] - 2021-01-20
+
+### Added
+
+- Add `DefaultGRPCPort` constant
+
+### Changed
+
+- `DNSTargetDiscoverer` now uses `DefaultGRPCPort` by default
+
 ## [0.1.0] - 2021-01-20
 
 - Initial release
 
 <!-- references -->
 [Unreleased]: https://github.com/dogmatiq/discoverkit
 [0.1.0]: https://github.com/dogmatiq/discoverkit/releases/tag/v0.1.0
+[0.1.1]: https://github.com/dogmatiq/discoverkit/releases/tag/v0.1.1
 
 <!-- version template
 ## [0.0.1] - YYYY-MM-DD

dns.go

@@ -31,8 +31,8 @@ type DNSTargetDiscoverer struct {
 	// an IP address.
 	//
 	// If NewTargets is nil the discoverer constructs a single Target for each
-	// discovered address. The target name is the discovered address and no
-	// explicit port is specified.
+	// discovered address. The target name is built using the discovered address
+	// as the host and the DefaultGRPCPort constant for the port.
 	NewTargets func(ctx context.Context, addr string) (targets []Target, err error)
 
 	// LookupHost is the function used to query the host.
@@ -174,6 +174,8 @@ func (d *DNSTargetDiscoverer) newTargets(ctx context.Context, addr string) ([]Ta
 	}
 
 	return []Target{
-		{Name: addr},
+		{
+			Name: net.JoinHostPort(addr, DefaultGRPCPort),
+		},
 	}, nil
 }

dns_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"net"
+	"strings"
 	"time"
 
 	. "github.com/dogmatiq/discoverkit"
@@ -58,8 +59,8 @@ var _ = Describe("type DNSTargetDiscoverer", func() {
 
 			Expect(err).To(Equal(context.Canceled))
 			Expect(targets).To(ConsistOf(
-				Target{Name: "<addr-1>"},
-				Target{Name: "<addr-2>"},
+				Target{Name: "<addr-1>:50555"},
+				Target{Name: "<addr-2>:50555"},
 			))
 		})
 
@@ -84,7 +85,7 @@ var _ = Describe("type DNSTargetDiscoverer", func() {
 					targetCtx context.Context,
 					t Target,
 				) {
-					if t.Name == "<addr-1>" {
+					if strings.Contains(t.Name, "<addr-1>") {
 						go func() {
 							<-targetCtx.Done()
 							close(done)
@@ -151,8 +152,8 @@ var _ = Describe("type DNSTargetDiscoverer", func() {
 					cancel()
 					Expect(t.Name).To(
 						Or(
-							Equal("127.0.0.1"),
-							Equal("::1"),
+							Equal("127.0.0.1:50555"),
+							Equal("[::1]:50555"),
 						),
 					)
 				},

server.go

@@ -7,6 +7,12 @@ import (
 	"github.com/dogmatiq/interopspec/discoverspec"
 )
 
+const (
+	// DefaultGRPCPort is the default TCP port used by servers that implement
+	// the APIs in interopspec, in particular the DiscoverAPI.
+	DefaultGRPCPort = "50555"
+)
+
 // Server is an implementation of discoverspec.DiscoverAPIServer.
 type Server struct {
 	m sync.Mutex