Implement default server authenticators (#4558)

* Implement default server authenticators

Allow the interfaces to be extended without affecting implementations by allowing authenticators to provide which functions to override.

This is a non-breaking change, and current implementations might be changed in the future to use this.

Fixes #4556

Signed-off-by: Juraci Paixão Kröhling <juraci@kroehling.de>

* fixuop

Signed-off-by: Juraci Paixão Kröhling <juraci@kroehling.de>

* Add missing godoc

Signed-off-by: Juraci Paixão Kröhling <juraci@kroehling.de>

CHANGELOG.md

@@ -24,6 +24,7 @@
     in a future release.
   - `service.telemetry.metrics.level` and `service.telemetry.metrics.address`
     should be used to configure collector self-metrics.
+- `configauth`: add helpers to create new server authenticators. (#4558)
 
 ## 🧰 Bug fixes 🧰
 

config/configauth/configauth_test.go

@@ -31,7 +31,7 @@ func TestGetServerAuthenticator(t *testing.T) {
 	}{
 		{
 			desc:          "obtain server authenticator",
-			authenticator: &MockServerAuthenticator{},
+			authenticator: NewServerAuthenticator(),
 			expected:      nil,
 		},
 		{
@@ -87,7 +87,7 @@ func TestGetClientAuthenticator(t *testing.T) {
 		},
 		{
 			desc:          "not a client authenticator",
-			authenticator: &MockServerAuthenticator{},
+			authenticator: NewServerAuthenticator(),
 			expected:      errNotClientAuthenticator,
 		},
 	}

config/configauth/default_serverauthenticator.go

@@ -0,0 +1,86 @@
+// Copyright  The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package configauth // import "go.opentelemetry.io/collector/config/configauth"
+
+import (
+	"context"
+
+	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/component/componenthelper"
+)
+
+var _ ServerAuthenticator = (*defaultServerAuthenticator)(nil)
+
+// Option represents the possible options for NewServerAuthenticator.
+type Option func(*defaultServerAuthenticator)
+
+type defaultServerAuthenticator struct {
+	AuthenticateFunc
+	componenthelper.StartFunc
+	componenthelper.ShutdownFunc
+}
+
+// WithAuthenticate specifies which function to use to perform the authentication.
+func WithAuthenticate(authenticateFunc AuthenticateFunc) Option {
+	return func(o *defaultServerAuthenticator) {
+		o.AuthenticateFunc = authenticateFunc
+	}
+}
+
+// WithStart overrides the default `Start` function for a component.Component.
+// The default always returns nil.
+func WithStart(startFunc componenthelper.StartFunc) Option {
+	return func(o *defaultServerAuthenticator) {
+		o.StartFunc = startFunc
+	}
+}
+
+// WithShutdown overrides the default `Shutdown` function for a component.Component.
+// The default always returns nil.
+func WithShutdown(shutdownFunc componenthelper.ShutdownFunc) Option {
+	return func(o *defaultServerAuthenticator) {
+		o.ShutdownFunc = shutdownFunc
+	}
+}
+
+// NewServerAuthenticator returns a ServerAuthenticator configured with the provided options.
+func NewServerAuthenticator(options ...Option) ServerAuthenticator {
+	bc := &defaultServerAuthenticator{
+		AuthenticateFunc: func(ctx context.Context, headers map[string][]string) (context.Context, error) { return ctx, nil },
+		StartFunc:        func(ctx context.Context, host component.Host) error { return nil },
+		ShutdownFunc:     func(ctx context.Context) error { return nil },
+	}
+
+	for _, op := range options {
+		op(bc)
+	}
+
+	return bc
+}
+
+// Authenticate performs the authentication.
+func (a *defaultServerAuthenticator) Authenticate(ctx context.Context, headers map[string][]string) (context.Context, error) {
+	return a.AuthenticateFunc(ctx, headers)
+}
+
+// Start the component.
+func (a *defaultServerAuthenticator) Start(ctx context.Context, host component.Host) error {
+	return a.StartFunc(ctx, host)
+}
+
+// Shutdown stops the component.
+func (a *defaultServerAuthenticator) Shutdown(ctx context.Context) error {
+	return a.ShutdownFunc(ctx)
+}

config/configauth/default_serverauthenticator_test.go

@@ -0,0 +1,95 @@
+// Copyright  The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package configauth
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/component/componenttest"
+)
+
+func TestDefaultValues(t *testing.T) {
+	// prepare
+	e := NewServerAuthenticator()
+
+	// test
+	t.Run("start", func(t *testing.T) {
+		err := e.Start(context.Background(), componenttest.NewNopHost())
+		assert.NoError(t, err)
+	})
+
+	t.Run("authenticate", func(t *testing.T) {
+		ctx, err := e.Authenticate(context.Background(), make(map[string][]string))
+		assert.NotNil(t, ctx)
+		assert.NoError(t, err)
+	})
+
+	t.Run("shutdown", func(t *testing.T) {
+		err := e.Shutdown(context.Background())
+		assert.NoError(t, err)
+	})
+}
+
+func TestWithAuthenticateFunc(t *testing.T) {
+	// prepare
+	authCalled := false
+	e := NewServerAuthenticator(
+		WithAuthenticate(func(ctx context.Context, headers map[string][]string) (context.Context, error) {
+			authCalled = true
+			return ctx, nil
+		}),
+	)
+
+	// test
+	_, err := e.Authenticate(context.Background(), make(map[string][]string))
+
+	// verify
+	assert.True(t, authCalled)
+	assert.NoError(t, err)
+}
+
+func TestWithStart(t *testing.T) {
+	called := false
+	e := NewServerAuthenticator(WithStart(func(c context.Context, h component.Host) error {
+		called = true
+		return nil
+	}))
+
+	// test
+	err := e.Start(context.Background(), componenttest.NewNopHost())
+
+	// verify
+	assert.True(t, called)
+	assert.NoError(t, err)
+}
+
+func TestWithShutdown(t *testing.T) {
+	called := false
+	e := NewServerAuthenticator(WithShutdown(func(c context.Context) error {
+		called = true
+		return nil
+	}))
+
+	// test
+	err := e.Shutdown(context.Background())
+
+	// verify
+	assert.True(t, called)
+	assert.NoError(t, err)
+}

config/configgrpc/configgrpc_test.go

@@ -151,7 +151,7 @@ func TestGrpcServerAuthSettings(t *testing.T) {
 	}
 	host := &mockHost{
 		ext: map[config.ComponentID]component.Extension{
-			config.NewComponentID("mock"): &configauth.MockServerAuthenticator{},
+			config.NewComponentID("mock"): configauth.NewServerAuthenticator(),
 		},
 	}
 	opts, err := gss.ToServerOption(host, componenttest.NewNopTelemetrySettings())

config/confighttp/confighttp_test.go

@@ -775,14 +775,15 @@ func TestServerAuth(t *testing.T) {
 			AuthenticatorID: config.NewComponentID("mock"),
 		},
 	}
+
 	host := &mockHost{
 		ext: map[config.ComponentID]component.Extension{
-			config.NewComponentID("mock"): &configauth.MockServerAuthenticator{
-				AuthenticateFunc: func(ctx context.Context, headers map[string][]string) (context.Context, error) {
+			config.NewComponentID("mock"): configauth.NewServerAuthenticator(
+				configauth.WithAuthenticate(func(ctx context.Context, headers map[string][]string) (context.Context, error) {
 					authCalled = true
 					return ctx, nil
-				},
-			},
+				}),
+			),
 		},
 	}