Function Compute:Trigger a function with a GetObject request using an Object FC Access Point

Step 1: Create an Object FC Access Point

1. Log on to the OSS console. In the navigation pane on the left, 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, set the following parameters and click OK.

   Configuration item	Description
   Region	Select the region where the access point to associate is located. This is also the region where the OSS bucket is located.
   Object FC Access Point Name	Enter a name for the Object FC Access Point.
   Supporting Access Point	Select the created access point.
   OSS API	Select GetObject.
   Function to Invoke	Select the target FC function and select the FC Function Supports Range GetObject Requests check box.
   FC Function Version	Select the version of the created function. By default, the LATEST version is used.

3. Complete the role authorization.

   Important

   If you are using the Object FC Access Point feature for the first time, click Access Point Permission Delegation to complete the role authorization. Otherwise, you cannot use Object FC Access Points to access functions.

   

Step 2: Write 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 code in the index.py file with the following sample code. This topic uses a function whose runtime is Python 3.10 as an example. For more information about sample code, see Write request functions.

   # -*- coding: utf-8 -*-
   import io
   from PIL import Image
   import oss2
   import json
   
   # In this example, the endpoint of the China (Qingdao) region is used.
   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)
       # Call the Image method to create an object of 200 × 200 pixels and draw a red rectangle for the object.
       # After the adjustments, write the content to the body of the write_get_object_response request.
       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 Terminal > New Terminal 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 Code.

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 the alias to call the GetObject operation.

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

2. In the list of Object FC Access Points, obtain the Object FC Access Point Alias of the target access point.

   

3. Use one of the following methods to call the GetObject operation with the Object FC Access Point alias to test whether the function is automatically triggered.

   Use an SDK

   1. Install the OSS SDK for Python. Only OSS SDK for Python 2.18.3 and later supports accessing OSS resources using the alias of an Object FC Access Point.

      pip3 install oss

   2. Run the following Python sample script on your computer.

      Replace the endpoint, bucketname, and bucket.get_object_to_file parameters in the following sample code with your actual values.

      • endpoint: The endpoint of the OSS region.

      • bucketname: The alias of the target Object FC Access Point that you obtained in the previous step.

      • bucket.get_object_to_file: Replace yourObjectName with the name of an object in your OSS bucket and yourLocalFile with the local path where you want to save the file.

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

   Use the ossutil command-line tool

   Install ossutil and run the following command to test.

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

   Use a REST API

   When you send a GetObject request to access OSS resources, you must specify the alias of the Object FC Access Point that you obtained in the previous step in the Host header. The following code provides an example:

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