Function Compute:Use an Object FC access point to trigger functions

Step 1: Create an Object FC Access Point

1. Log on to the OSS console. In the left-side navigation pane, click Object FC Access Points.

2. On the Object FC Access Points page, click Create Object FC Access Point. In the Create Object FC Access Point panel, configure the following parameters and click OK.

   Parameter	Description
   Region	Select the same region for the supporting access point and the OSS bucket.
   Object FC Access Point Name	Enter a name for the Object FC Access Point.
   Supporting Access Point	Select a previously created access point.
   OSS API	Select GetObject.
   Function to Invoke	Select the target FC function, and then select the FC Function Supports Range GetObject Requests check box.
   FC Function Version	Select a version of the function. The LATEST version is used by default.

3. Grant the required permissions.

   Important

   If this is the first time you use an Object FC Access Point, click Access Point Permission Delegation to grant the necessary permissions. Otherwise, the Object FC Access Point cannot access the function.

   The Object FC Access Point enters the Creating state. The access point becomes ready in about 10 minutes. You can use the access point only after its status changes to Created. Click Go to RAM for Authorization to grant permissions, and then click Complete.

Step 2: Write the function code

1. Log on to the Function Compute console. In the left-side navigation pane, click Functions.

2. In the top navigation bar, select a region. On the Functions page, click the function that you want to manage.

3. Choose Function Details > Code. In the code editor, replace the content of the index.py file with the following sample code. This example uses a function with the Python 3.10 runtime. For more code samples, see Write request functions.

   # -*- coding: utf-8 -*-
   import io
   from PIL import Image
   import oss2
   import json
   # Example: China (Qingdao) region endpoint.
   endpoint = 'http://oss-cn-qingdao.aliyuncs.com'
   fwd_status = '200'
   # FC function entry
   def handler(event, context):
       evt = json.loads(event)
       creds = context.credentials
       # Do not forget security_token
       auth = oss2.StsAuth(creds.access_key_id, creds.access_key_secret, creds.security_token)
       headers = dict()    
       event_ctx = evt["getObjectContext"]
       route = event_ctx["outputRoute"]
       token = event_ctx["outputToken"]
       print(evt)
       endpoint = route
       service = oss2.Service(auth, endpoint)
       # Create a 200x200 red PNG image.
       # Write the transformed image to the GetObject response.
       image = Image.new('RGB', (200, 200), color=(255, 0, 0))
       transformed = io.BytesIO()
       image.save(transformed, "png")
       resp = service.write_get_object_response(route, token, fwd_status, transformed.getvalue(), headers)
       print('status: {0}'.format(resp.status))
       print(resp.headers)
       return 'success'

4. On the Code tab, choose to open a terminal window. Run the following command to update the OSS Python SDK version.

   pip install oss2 "pyopenssl>=23.0.0" "urllib3==1.26.15" "charset-normalizer==2.1.1"  -t .

5. Click Deploy.

Step 3: Use the Object FC Access Point

After you create an Object FC Access Point, OSS automatically generates an alias for it. You can use this alias to call the GetObject API.

1. Log on to the OSS console. In the left-side navigation pane, click Object FC Access Points.

2. On the Object FC Access Points page, find the Object FC Access Point and copy its alias from the Object FC Access Point Alias column.

3. Use one of the following methods to call the GetObject API by using the Object FC Access Point Alias to verify that the function is triggered automatically.

   SDK

   1. Accessing resources with an Object FC Access Point Alias requires OSS SDK for Python 2.18.3 or later.

      pip3 install oss

   2. Run the following Python sample script locally.

      Before you run the script, replace the endpoint and bucket_name placeholders, and the parameters within the bucket.get_object_to_file method, with your actual values.

      • endpoint: The access endpoint of OSS.

      • bucket_name: The Object FC Access Point Alias that you copied in the previous step.

      • bucket.get_object_to_file: Replace yourObjectName with the object name and yourLocalFile with the destination local file path.

      # -*- coding: utf-8 -*-
      import oss2
      from oss2.credentials import EnvironmentVariableCredentialsProvider
      # Obtain access credentials from environment variables. Before you run this code, make sure the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set.
      auth = oss2.ProviderAuth(EnvironmentVariableCredentialsProvider())
      # Use the public endpoint of the Object FC Access Point to access resources.
      endpoint = "https://oss-cn-qingdao.aliyuncs.com"
      # Use the internal endpoint of the Object FC Access Point to access resources.
      # endpoint = "https://oss-cn-qingdao-internal.aliyuncs.com"
      # Specify the Object FC Access Point Alias.
      bucket_name = "****-d54843759613953fe5b17b6f16d7****-opapalias"
      bucket = oss2.Bucket(auth, endpoint=endpoint, bucket_name=bucket_name)
      # Set yourObjectName to the full path of the object. The path does not include the bucket name.
      # Set yourLocalFile to the local file path. If the file exists, it is overwritten. If not, a new file is created.
      bucket.get_object_to_file('yourObjectName', 'yourLocalFile')

   ossutil CLI

   Install ossutil and run the following command to test the configuration.

   ossutil cp oss://****-d54843759613953fe5b17b6f16d7****-opapalias/demo.txt /Users/demo/Desktop/demo.txt

   REST API

   When you send a GetObject request to an OSS resource, use the copied Object FC Access Point Alias as the Host header value. The following example shows a sample request:

   GET /ObjectName HTTP/1.1
   Host: fc-ap-01-3b00521f653d2b3223680ec39dbbe2****-opapalias.oss-cn-qingdao.aliyuncs.com
   Date: GMT Date
   Authorization: SignatureValue