Add DNS name resolver. Add unit tests. (#743)

* Add DNS name resolver. Add unit tests.

* Fix code format

* Add namespace support for DNS name resolver. Fix comments

* Update dns.go

* Update dns_test.go

* Update dns.go

* Update dns_test.go

Co-authored-by: Andrey Bogdanov <andrey.bogdanov@zyfra.com>
Co-authored-by: Artur Souza <artursouza.ms@outlook.com>
Co-authored-by: Aaron Crawfis <Aaron.Crawfis@microsoft.com>

nameresolution/dns/dns.go

@@ -0,0 +1,32 @@
+// ------------------------------------------------------------
+// Copyright (c) Microsoft Corporation and Dapr Contributors.
+// Licensed under the MIT License.
+// ------------------------------------------------------------
+
+package dns
+
+import (
+	"fmt"
+
+	"github.com/dapr/components-contrib/nameresolution"
+	"github.com/dapr/kit/logger"
+)
+
+type resolver struct {
+	logger logger.Logger
+}
+
+// NewResolver creates DNS name resolver.
+func NewResolver(logger logger.Logger) nameresolution.Resolver {
+	return &resolver{logger: logger}
+}
+
+// Init initializes DNS name resolver.
+func (k *resolver) Init(metadata nameresolution.Metadata) error {
+	return nil
+}
+
+// ResolveID resolves name to address in orchestrator.
+func (k *resolver) ResolveID(req nameresolution.ResolveRequest) (string, error) {
+	return fmt.Sprintf("%s-dapr.%s.svc:%d", req.ID, req.Namespace, req.Port), nil
+}

nameresolution/dns/dns_test.go

@@ -0,0 +1,25 @@
+// ------------------------------------------------------------
+// Copyright (c) Microsoft Corporation and Dapr Contributors.
+// Licensed under the MIT License.
+// ------------------------------------------------------------
+
+package dns
+
+import (
+	"testing"
+
+	"github.com/dapr/components-contrib/nameresolution"
+	"github.com/dapr/kit/logger"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestResolve(t *testing.T) {
+	resolver := NewResolver(logger.NewLogger("test"))
+	request := nameresolution.ResolveRequest{ID: "myid", Namespace: "abc", Port: 1234}
+
+	u := "myid-dapr.abc.svc:1234"
+	target, err := resolver.ResolveID(request)
+
+	assert.Nil(t, err)
+	assert.Equal(t, target, u)
+}