pubsub: add samples for dead letter topics

go.mod

@@ -1,19 +1,19 @@
 module github.com/GoogleCloudPlatform/golang-samples
 
-go 1.11
+go 1.14
 
 require (
 	cloud.google.com/go v0.55.0
 	cloud.google.com/go/bigquery v1.5.0
-	cloud.google.com/go/bigtable v1.1.0
+	cloud.google.com/go/bigtable v1.3.0
 	cloud.google.com/go/datastore v1.1.0
-	cloud.google.com/go/firestore v1.1.0
+	cloud.google.com/go/firestore v1.1.1
 	cloud.google.com/go/logging v1.0.0
 	cloud.google.com/go/pubsub v1.3.1
 	cloud.google.com/go/spanner v1.4.0
 	cloud.google.com/go/storage v1.6.0
 	contrib.go.opencensus.io/exporter/stackdriver v0.13.0
-	github.com/aws/aws-sdk-go v1.29.29
+	github.com/aws/aws-sdk-go v1.29.30
 	github.com/bmatcuk/doublestar v1.2.2
 	github.com/bmizerany/assert v0.0.0-20160611221934-b7ed37b82869 // indirect
 	github.com/bradfitz/gomemcache v0.0.0-20190913173617-a41fca850d0b
@@ -36,15 +36,15 @@ require (
 	github.com/mailjet/mailjet-apiv3-go v0.0.0-20190724151621-55e56f74078c
 	github.com/philhofer/fwd v1.0.0 // indirect
 	github.com/sendgrid/smtpapi-go v0.6.0 // indirect
-	github.com/tinylib/msgp v1.1.0 // indirect
+	github.com/tinylib/msgp v1.1.2 // indirect
 	go.opencensus.io v0.22.3
 	golang.org/x/exp v0.0.0-20200320212757-167ffe94c325
 	golang.org/x/net v0.0.0-20200320220750-118fecf932d8
 	golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d
 	golang.org/x/text v0.3.2
 	google.golang.org/api v0.20.0
 	google.golang.org/appengine v1.6.5
-	google.golang.org/genproto v0.0.0-20200319113533-08878b785e9c
+	google.golang.org/genproto v0.0.0-20200323114720-3f67cca34472
 	google.golang.org/grpc v1.28.0
 	gopkg.in/sendgrid/sendgrid-go.v2 v2.0.0
 	gopkg.in/yaml.v2 v2.2.8

pubsub/subscriptions/dead_letter_create.go

@@ -0,0 +1,59 @@
+// Copyright 2020 Google LLC
+//
+// 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
+//
+//     https://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 subscriptions
+
+// [START pubsub_dead_letter_create_subscription]
+import (
+	"context"
+	"fmt"
+	"io"
+	"time"
+
+	"cloud.google.com/go/pubsub"
+)
+
+// createSubWithDeadLetter creates a subscription with a dead letter policy.
+func createSubWithDeadLetter(w io.Writer, projectID, subID string, topicID string, fullyQualifiedDeadLetterTopic string) error {
+	// projectID := "my-project-id"
+	// subID := "my-sub"
+	// topicID := "my-topic"
+	// fullyQualifiedDeadLetterTopic := "projects/my-project/topics/my-dead-letter-topic"
+	ctx := context.Background()
+	client, err := pubsub.NewClient(ctx, projectID)
+	if err != nil {
+		return fmt.Errorf("pubsub.NewClient: %v", err)
+	}
+
+	topic := client.Topic(topicID)
+
+	subConfig := pubsub.SubscriptionConfig{
+		Topic:       topic,
+		AckDeadline: 20 * time.Second,
+		DeadLetterPolicy: &pubsub.DeadLetterPolicy{
+			DeadLetterTopic:     fullyQualifiedDeadLetterTopic,
+			MaxDeliveryAttempts: 10,
+		},
+	}
+
+	sub, err := client.CreateSubscription(ctx, subID, subConfig)
+	if err != nil {
+		return fmt.Errorf("CreateSubscription: %v", err)
+	}
+	fmt.Fprintf(w, "Created subscription (%s) with dead letter topic (%s)\n", sub.String(), fullyQualifiedDeadLetterTopic)
+	fmt.Fprintln(w, "To process dead letter messages, remember to add a subscription to your dead letter topic.")
+	return nil
+}
+
+// [END pubsub_dead_letter_create_subscription]

pubsub/subscriptions/dead_letter_delivery_attempt.go

@@ -0,0 +1,56 @@
+// Copyright 2020 Google LLC
+//
+// 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
+//
+//     https://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 subscriptions
+
+// [START pubsub_dead_letter_delivery_attempt]
+import (
+	"context"
+	"fmt"
+	"io"
+	"time"
+
+	"cloud.google.com/go/pubsub"
+)
+
+func pullMsgsDeadLetterDeliveryAttempt(w io.Writer, projectID, subID string) error {
+	// projectID := "my-project-id"
+	// subID := "my-sub"
+	ctx := context.Background()
+	client, err := pubsub.NewClient(ctx, projectID)
+	if err != nil {
+		return fmt.Errorf("pubsub.NewClient: %v", err)
+	}
+
+	// Receive messages for 10 seconds.
+	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
+	defer cancel()
+
+	sub := client.Subscription(subID)
+	err = sub.Receive(ctx, func(ctx context.Context, msg *pubsub.Message) {
+		// When dead lettering is enabled, the delivery attempt field is a pointer to the
+		// the number of times the service has attempted to delivery a message.
+		// Otherwise, the field is nil.
+		if msg.DeliveryAttempt != nil {
+			fmt.Fprintf(w, "message: %s, delivery attempts: %d", msg.Data, *msg.DeliveryAttempt)
+		}
+		msg.Ack()
+	})
+	if err != nil {
+		return fmt.Errorf("got error in Receive: %v", err)
+	}
+	return nil
+}
+
+// [END pubsub_dead_letter_delivery_attempt]

pubsub/subscriptions/dead_letter_remove.go

@@ -0,0 +1,46 @@
+// Copyright 2020 Google LLC
+//
+// 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
+//
+//     https://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 subscriptions
+
+// [START pubsub_dead_letter_remove]
+import (
+	"context"
+	"fmt"
+	"io"
+
+	"cloud.google.com/go/pubsub"
+)
+
+// removeDeadLetterTopic removes the dead letter policy from a subscription.
+func removeDeadLetterTopic(w io.Writer, projectID, subID string) error {
+	// projectID := "my-project-id"
+	// subID := "my-sub"
+	ctx := context.Background()
+	client, err := pubsub.NewClient(ctx, projectID)
+	if err != nil {
+		return fmt.Errorf("pubsub.NewClient: %v", err)
+	}
+
+	subConfig, err := client.Subscription(subID).Update(ctx, pubsub.SubscriptionConfigToUpdate{
+		DeadLetterPolicy: &pubsub.DeadLetterPolicy{},
+	})
+	if err != nil {
+		return fmt.Errorf("Update: %v", err)
+	}
+	fmt.Fprintf(w, "Updated subscription config: %+v\n", subConfig)
+	return nil
+}
+
+// [END pubsub_dead_letter_remove]

pubsub/subscriptions/dead_letter_update.go

@@ -0,0 +1,52 @@
+// Copyright 2020 Google LLC
+//
+// 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
+//
+//     https://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 subscriptions
+
+// [START pubsub_dead_letter_update]
+import (
+	"context"
+	"fmt"
+	"io"
+
+	"cloud.google.com/go/pubsub"
+)
+
+// updateDeadLetter updates an existing subscription with a dead letter policy.
+func updateDeadLetter(w io.Writer, projectID, subID string, fullyQualifiedDeadLetterTopic string) error {
+	// projectID := "my-project-id"
+	// subID := "my-sub"
+	// fullyQualifiedDeadLetterTopic := "projects/my-project/topics/my-dead-letter-topic"
+	ctx := context.Background()
+	client, err := pubsub.NewClient(ctx, projectID)
+	if err != nil {
+		return fmt.Errorf("pubsub.NewClient: %v", err)
+	}
+
+	updateConfig := pubsub.SubscriptionConfigToUpdate{
+		DeadLetterPolicy: &pubsub.DeadLetterPolicy{
+			DeadLetterTopic:     fullyQualifiedDeadLetterTopic,
+			MaxDeliveryAttempts: 20,
+		},
+	}
+
+	subConfig, err := client.Subscription(subID).Update(ctx, updateConfig)
+	if err != nil {
+		return fmt.Errorf("Update: %v", err)
+	}
+	fmt.Fprintf(w, "Updated subscription config: %+v\n", subConfig)
+	return nil
+}
+
+// [END pubsub_dead_letter_update]