当对象上传到我的GCS存储桶时，如何得到通知？ [英] How do I get notified when an object is uploaded to my GCS bucket?

问题描述

我有一个应用程序可以将照片定期上传到GCS存储区。当这些照片上传时，我需要添加缩略图并做一些分析。如何为存储桶设置通知？

解决方案

执行此操作的方法是创建Cloud Pub /新对象，并配置您的GCS存储桶以在创建新对象时将消息发布到该主题。

首先，我们创建一个存储桶PHOTOBUCKET：

  $ gsutil mb gs：// PHOTOBUCKET 
  

现在，请确保激活了Cloud Pub / Sub API 。
$ b 接下来，让我们创建一个Cloud Pub / Sub主题并使用 gsutil将其连接到我们的GCS存储桶：

  $ gsutil通知创建\ 
 -t uploadedphotos -f json \ 
 -e OBJECT_FINALIZE gs：// PHOTOBUCKET 
  

-t 指定发布/订阅主题。如果该主题尚不存在， gsutil 会为您创建。

-e 指定您只对OBJECT_FINALIZE消息（正在创建的对象）感兴趣。否则，您会在主题中收到各种消息。

-f 指定您希望有效负载的消息作为JSON API的对象元数据。

请注意，这需要最新版本的gsutil，因此请务必更新到最新版本的 gcloud ，或运行 gsutil update ，如果您使用独立gsutil。

<现在我们已经配置了通知和抽取，但我们希望看到它们。让我们创建一个Pub / Sub订阅：

$ gcloud beta pubsub订阅创建processphotos --topic = uploadedphotos

现在我们只需要阅读这些消息。 下面是一个Python示例这样做。这里有一些相关的部分：

$ $ $ $ $ $ $ $ $ $ $ $ $ $ def $ b订阅= pubsub.subscription.Subscription（
subscription_id，客户端=客户端）
，而True：
拉= subscription.pull（max_messages = 100）
为ack_id， ：
print（'Received message {0}：\\\
{1}'。format（
message.message_id，summarize（message）））
subscription.acknowledge（[ack_id]）

def总结（消息）：
＃[START parse_message]
data = message.data
attributes = message.attributes

event_type = attributes ['eventType']
bucket_id = attributes ['bucketId']
object_id = attributes ['objectId']
return用户上传％s，我们应该在这里做点什么。 ％object_id


以下是关于这个系统如何工作的更多信息：

https://cloud.google.com/storage/docs/报告变更
https://cloud.google.com/ storage / docs / pubsub-notifications

I have an app that uploads photos regularly to a GCS bucket. When those photos are uploaded, I need to add thumbnails and do some analysis. How do I set up notifications for the bucket?

解决方案

The way to do this is to create a Cloud Pub/Sub topic for new objects and to configure your GCS bucket to publish messages to that topic when new objects are created.

First, let's create a bucket PHOTOBUCKET:

$ gsutil mb gs://PHOTOBUCKET

Now, make sure you've activated the Cloud Pub/Sub API.

Next, let's create a Cloud Pub/Sub topic and wire it to our GCS bucket with gsutil:

$ gsutil notification create \
    -t uploadedphotos -f json \
    -e OBJECT_FINALIZE gs://PHOTOBUCKET

The -t specifies the Pub/Sub topic. If the topic doesn't already exist, gsutil will create it for you.

The -e specifies that you're only interested in OBJECT_FINALIZE messages (objects being created). Otherwise you'll get every kind of message in your topic.

The -f specifies that you want the payload of the messages to be the object metadata for the JSON API.

Note that this requires a recent version of gsutil, so be sure to update to the latest version of gcloud, or run gsutil update if you use a standalone gsutil.

Now we have notifications configured and pumping, but we'll want to see them. Let's create a Pub/Sub subscription:

$ gcloud beta pubsub subscriptions create processphotos --topic=uploadedphotos

Now we just need to read these messages. Here's a Python example of doing just that. Here are the relevant bits:

def poll_notifications(subscription_id):
    client = pubsub.Client()
    subscription = pubsub.subscription.Subscription(
        subscription_id, client=client)
    while True:
        pulled = subscription.pull(max_messages=100)
        for ack_id, message in pulled:
            print('Received message {0}:\n{1}'.format(
                message.message_id, summarize(message)))
            subscription.acknowledge([ack_id])

def summarize(message):
    # [START parse_message]
    data = message.data
    attributes = message.attributes

    event_type = attributes['eventType']
    bucket_id = attributes['bucketId']
    object_id = attributes['objectId']
    return "A user uploaded %s, we should do something here." % object_id

Here is some more reading on how this system works:

https://cloud.google.com/storage/docs/reporting-changes https://cloud.google.com/storage/docs/pubsub-notifications

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