在 Cloud Functions (第 1 代) 上运行的由 Pub/Sub 触发的函数示例。
深入探索
如需查看包含此代码示例的详细文档,请参阅以下内容:
- .NET 语言
- 直接调用 Cloud Functions 函数
- Cloud Pub/Sub 教程(第 2 代)
- Cloud Pub/Sub 教程第 1 代
- JVM 语言
- 测试事件驱动函数
- 使用 Pub/Sub 模拟器进行测试
代码示例
C#
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;
}
}
}
Go
// Package helloworld provides a set of Cloud Functions samples.
package helloworld
import (
"context"
"log"
)
// 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 Pub/Sub message.
func HelloPubSub(ctx context.Context, m PubSubMessage) error {
name := string(m.Data) // Automatically decoded from base64.
if name == "" {
name = "World"
}
log.Printf("Hello, %s!", name)
return nil
}
Java
import com.google.cloud.functions.BackgroundFunction;
import com.google.cloud.functions.Context;
import functions.eventpojos.PubsubMessage;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
import java.util.logging.Level;
import java.util.logging.Logger;
public class HelloPubSub implements BackgroundFunction<PubsubMessage> {
private static final Logger logger = Logger.getLogger(HelloPubSub.class.getName());
@Override
public void accept(PubsubMessage message, Context context) {
String name = "world";
if (message != null && message.getData() != null) {
name = new String(
Base64.getDecoder().decode(message.getData().getBytes(StandardCharsets.UTF_8)),
StandardCharsets.UTF_8);
}
logger.info(String.format("Hello %s!", name));
return;
}
}
Kotlin
import com.google.cloud.functions.BackgroundFunction
import com.google.cloud.functions.Context
import functions.eventpojos.PubsubMessage
import java.nio.charset.StandardCharsets
import java.util.Base64
import java.util.logging.Logger
class KotlinHelloPubSub : BackgroundFunction<PubsubMessage> {
override fun accept(message: PubsubMessage, context: Context) {
// name's default value is "world"
var name = "world"
if (message?.data != null) {
name = String(
Base64.getDecoder().decode(message.data!!.toByteArray(StandardCharsets.UTF_8)),
StandardCharsets.UTF_8)
}
LOGGER.info(String.format("Hello %s!", name))
return;
}
companion object {
private val LOGGER = Logger.getLogger(KotlinHelloPubSub::class.java.name)
}
}
Node.js
/**
* Background Cloud Function to be triggered by Pub/Sub.
* This function is exported by index.js, and executed when
* the trigger topic receives a message.
*
* @param {object} message The Pub/Sub message.
* @param {object} context The event metadata.
*/
exports.helloPubSub = (message, context) => {
const name = message.data
? Buffer.from(message.data, 'base64').toString()
: 'World';
console.log(`Hello, ${name}!`);
};
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);
}
Python
def hello_pubsub(event, context):
"""Background Cloud Function to be triggered by Pub/Sub.
Args:
event (dict): The dictionary with data specific to this type of
event. The `@type` field maps to
`type.googleapis.com/google.pubsub.v1.PubsubMessage`.
The `data` field maps to the PubsubMessage data
in a base64-encoded string. The `attributes` field maps
to the PubsubMessage attributes if any is present.
context (google.cloud.functions.Context): Metadata of triggering event
including `event_id` which maps to the PubsubMessage
messageId, `timestamp` which maps to the PubsubMessage
publishTime, `event_type` which maps to
`google.pubsub.topic.publish`, and `resource` which is
a dictionary that describes the service API endpoint
pubsub.googleapis.com, the triggering topic's name, and
the triggering event type
`type.googleapis.com/google.pubsub.v1.PubsubMessage`.
Returns:
None. The output is written to Cloud Logging.
"""
import base64
print("""This Function was triggered by messageId {} published at {} to {}
""".format(context.event_id, context.timestamp, context.resource["name"]))
if 'data' in event:
name = base64.b64decode(event['data']).decode('utf-8')
else:
name = 'World'
print('Hello {}!'.format(name))
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
后续步骤
如需搜索和过滤其他 Google Cloud 产品的代码示例,请参阅 Google Cloud 示例浏览器。