使用 Eventarc 從 Pub/Sub 觸發函式

必要的角色

您或管理員必須為部署者帳戶、觸發器身分，以及 Pub/Sub 服務代理人和 Cloud Storage 服務代理人授予下列 IAM 角色 (選用)。

建立 Pub/Sub 主題

在 Cloud Run 中，部署函式時不會自動建立 Pub/Sub 主題。在部署函式之前，請將訊息發布至這個 Pub/Sub 主題，藉此觸發函式：

gcloud pubsub topics create YOUR_TOPIC_NAME

準備應用程式

1. 將應用程式存放區範例複製到本機電腦中：

   Node.js

   git clone https://github.com/GoogleCloudPlatform/nodejs-docs-samples.git
   

   Python

   git clone https://github.com/GoogleCloudPlatform/python-docs-samples.git
   

   Go

   git clone https://github.com/GoogleCloudPlatform/golang-samples.git
   

   Java

   git clone https://github.com/GoogleCloudPlatform/java-docs-samples.git
   

   .NET

   git clone https://github.com/GoogleCloudPlatform/dotnet-docs-samples.git
   

   Ruby

   git clone https://github.com/GoogleCloudPlatform/ruby-docs-samples.git
   

   PHP

   git clone https://github.com/GoogleCloudPlatform/php-docs-samples.git
   

2. 變更為包含 Pub/Sub 存取範例程式碼的目錄：

   Node.js

   cd nodejs-docs-samples/functions/v2/helloPubSub/
   

   Python

   cd python-docs-samples/functions/v2/pubsub/
   

   Go

   cd golang-samples/functions/functionsv2/hellopubsub/
   

   Java

   cd java-docs-samples/functions/v2/pubsub/
   

   .NET

   cd dotnet-docs-samples/functions/helloworld/HelloPubSub/
   

   Ruby

   cd ruby-docs-samples/functions/helloworld/pubsub/
   

   PHP

   cd php-docs-samples/functions/helloworld_pubsub/
   

3. 查看程式碼範例：

   Node.js

   const functions = require('@google-cloud/functions-framework');
   
   // Register a CloudEvent callback with the Functions Framework that will
   // be executed when the Pub/Sub trigger topic receives a message.
   functions.cloudEvent('helloPubSub', cloudEvent => {
     // The Pub/Sub message is passed as the CloudEvent's data payload.
     const base64name = cloudEvent.data.message.data;
   
     const name = base64name
       ? Buffer.from(base64name, 'base64').toString()
       : 'World';
   
     console.log(`Hello, ${name}!`);
   });

   Python

   import base64
   
   from cloudevents.http import CloudEvent
   import functions_framework
   
   
   # Triggered from a message on a Cloud Pub/Sub topic.
   @functions_framework.cloud_event
   def subscribe(cloud_event: CloudEvent) -> None:
       # Print out the data from Pub/Sub, to prove that it worked
       print(
           "Hello, " + base64.b64decode(cloud_event.data["message"]["data"]).decode() + "!"
       )
   
   

   Go

   
   // Package helloworld provides a set of Cloud Functions samples.
   package helloworld
   
   import (
   	"context"
   	"fmt"
   	"log"
   
   	"github.com/GoogleCloudPlatform/functions-framework-go/functions"
   	"github.com/cloudevents/sdk-go/v2/event"
   )
   
   func init() {
   	functions.CloudEvent("HelloPubSub", helloPubSub)
   }
   
   // MessagePublishedData contains the full Pub/Sub message
   // See the documentation for more details:
   // https://cloud.google.com/eventarc/docs/cloudevents#pubsub
   type MessagePublishedData struct {
   	Message PubSubMessage
   }
   
   // PubSubMessage is the payload of a Pub/Sub event.
   // See the documentation for more details:
   // https://cloud.google.com/pubsub/docs/reference/rest/v1/PubsubMessage
   type PubSubMessage struct {
   	Data []byte `json:"data"`
   }
   
   // helloPubSub consumes a CloudEvent message and extracts the Pub/Sub message.
   func helloPubSub(ctx context.Context, e event.Event) error {
   	var msg MessagePublishedData
   	if err := e.DataAs(&msg); err != nil {
   		return fmt.Errorf("event.DataAs: %w", err)
   	}
   
   	name := string(msg.Message.Data) // Automatically decoded from base64.
   	if name == "" {
   		name = "World"
   	}
   	log.Printf("Hello, %s!", name)
   	return nil
   }
   

   Java

   import com.google.cloud.functions.CloudEventsFunction;
   import com.google.gson.Gson;
   import functions.eventpojos.PubSubBody;
   import io.cloudevents.CloudEvent;
   import java.nio.charset.StandardCharsets;
   import java.util.Base64;
   import java.util.logging.Logger;
   
   public class SubscribeToTopic implements CloudEventsFunction {
     private static final Logger logger = Logger.getLogger(SubscribeToTopic.class.getName());
   
     @Override
     public void accept(CloudEvent event) {
       // The Pub/Sub message is passed as the CloudEvent's data payload.
       if (event.getData() != null) {
         // Extract Cloud Event data and convert to PubSubBody
         String cloudEventData = new String(event.getData().toBytes(), StandardCharsets.UTF_8);
         Gson gson = new Gson();
         PubSubBody body = gson.fromJson(cloudEventData, PubSubBody.class);
         // Retrieve and decode PubSub message data
         String encodedData = body.getMessage().getData();
         String decodedData =
             new String(Base64.getDecoder().decode(encodedData), StandardCharsets.UTF_8);
         logger.info("Hello, " + decodedData + "!");
       }
     }
   }

   .NET

   using CloudNative.CloudEvents;
   using Google.Cloud.Functions.Framework;
   using Google.Events.Protobuf.Cloud.PubSub.V1;
   using Microsoft.Extensions.Logging;
   using System.Threading;
   using System.Threading.Tasks;
   
   namespace HelloPubSub;
   
   public class Function : ICloudEventFunction<MessagePublishedData>
   {
       private readonly ILogger _logger;
   
       public Function(ILogger<Function> logger) =>
           _logger = logger;
   
       public Task HandleAsync(CloudEvent cloudEvent, MessagePublishedData data, CancellationToken cancellationToken)
       {
           string nameFromMessage = data.Message?.TextData;
           string name = string.IsNullOrEmpty(nameFromMessage) ? "world" : nameFromMessage;
           _logger.LogInformation("Hello {name}", name);
           return Task.CompletedTask;
       }
   }

   Ruby

   require "functions_framework"
   require "base64"
   
   FunctionsFramework.cloud_event "hello_pubsub" do |event|
     # The event parameter is a CloudEvents::Event::V1 object.
     # See https://cloudevents.github.io/sdk-ruby/latest/CloudEvents/Event/V1.html
     name = Base64.decode64 event.data["message"]["data"] rescue "World"
   
     # A cloud_event function does not return a response, but you can log messages
     # or cause side effects such as sending additional events.
     logger.info "Hello, #{name}!"
   end

   PHP

   
   use CloudEvents\V1\CloudEventInterface;
   use Google\CloudFunctions\FunctionsFramework;
   
   // Register the function with Functions Framework.
   // This enables omitting the `FUNCTIONS_SIGNATURE_TYPE=cloudevent` environment
   // variable when deploying. The `FUNCTION_TARGET` environment variable should
   // match the first parameter.
   FunctionsFramework::cloudEvent('helloworldPubsub', 'helloworldPubsub');
   
   function helloworldPubsub(CloudEventInterface $event): void
   {
       $log = fopen(getenv('LOGGER_OUTPUT') ?: 'php://stderr', 'wb');
   
       $cloudEventData = $event->getData();
       $pubSubData = base64_decode($cloudEventData['message']['data']);
   
       $name = $pubSubData ? htmlspecialchars($pubSubData) : 'World';
       fwrite($log, "Hello, $name!" . PHP_EOL);
   }

部署事件導向函式

如要部署函式，請在包含範例程式碼的目錄中執行下列指令：

  gcloud run deploy FUNCTION \
        --source . \
        --function helloPubSub \
        --base-image BASE_IMAGE \

  gcloud run deploy FUNCTION \
        --source . \
        --function subscribe \
        --base-image BASE_IMAGE \

  gcloud run deploy FUNCTION \
        --source . \
        --function HelloPubSub \
        --base-image BASE_IMAGE \

  gcloud run deploy FUNCTION \
        --source . \
        --function functions.SubscribeToTopic \
        --base-image BASE_IMAGE \

  gcloud run deploy FUNCTION \
        --source . \
        --function HelloPubSub.Function \
        --base-image BASE_IMAGE \

  gcloud run deploy FUNCTION \
        --source . \
        --function hello_pubsub \
        --base-image BASE_IMAGE \

  gcloud run deploy FUNCTION \
        --source . \
        --function helloworldPubsub \
        --base-image BASE_IMAGE \

如果系統提示您在指定區域建立存放區，請按下 y 回應。部署完成後，Google Cloud CLI 會顯示服務執行的網址。

建立 Eventarc 觸發條件

如要使用 Pub/Sub 觸發條件部署函式，請在包含程式碼範例的目錄中執行下列指令：

1. 建立 Eventarc Pub/Sub 觸發條件：

   gcloud eventarc triggers create TRIGGER_NAME  \
       --location=${REGION} \
       --destination-run-service=FUNCTION \
       --destination-run-region=${REGION} \
       --event-filters="type=google.cloud.pubsub.topic.v1.messagePublished" \
       --service-account=PROJECT_NUMBER-compute@developer.gserviceaccount.com

   取代：

   • TRIGGER_NAME 替換為觸發條件的名稱。
   • FUNCTION 替換為函式名稱。
   • PROJECT_NUMBER 換成您的 Google Cloud 專案編號。

   請注意，在 Google Cloud 專案中首次建立 Eventarc 觸發條件時，Eventarc 服務代理程式可能會延遲佈建。您通常可以嘗試重新建立觸發條件來解決這個問題。詳情請參閱權限遭拒錯誤。

2. 確認觸發條件是否已成功建立。請注意，雖然觸發條件會立即建立，但觸發條件最多可能需要兩分鐘才能完全運作。

   gcloud eventarc triggers list --location=${REGION}

   畫面會顯示如下的輸出內容：

   NAME: helloworld-events
   TYPE: google.cloud.pubsub.topic.v1.messagePublished
   DESTINATION: Cloud Run service: helloworld-events
   ACTIVE: Yes
   LOCATION: us-central1
   

觸發函式

如要測試 Pub/Sub 函式，請按照下列步驟操作：

1. 將主題指派給變數：

   TOPIC_ID=$(gcloud eventarc triggers describe TRIGGER_NAME --location $REGION --format='value(transport.pubsub.topic)')
   

2. 將訊息發布到主題：

   gcloud pubsub topics publish $TOPIC_ID --message="Hello World"
   

Cloud Run 服務會記錄傳入訊息的內容。您可以在 Cloud Run 執行個體的「Logs」(記錄) 部分查看這項資訊：

1. 前往 Google Cloud 控制台。
2. 按一下函式。

3. 選取 [Logs] (記錄) 分頁標籤。

   記錄需要一些時間才會出現。如果您沒有立即看到記錄，請稍候片刻再查看一次。

4. 尋找「Hello World!」訊息。