Function Compute:Configure an OSS file system

Step 1: Configure OSS mounting

After an OSS mount target is configured for a service in Function Compute, all functions in the service can access files in the specified OSS bucket.

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

2. In the top navigation bar, select a region. On the Services page, find the desired service and click Configure in the Actions column.

3. In the Storage Configuration section on the Modify Service page, configure the following parameters and click Save.

   Parameter	Description	Example
   Mount OSS	Specify whether to enable OSS mounting. Valid values: Enable Disable	Enable
   OSS Mount Target: Configure OSS mount targets.
   Bucket	Select existing buckets. To create an OSS bucket, click Create OSS Bucket in the lower part of the page to go to the OSS console. For more information about billing of OSS, see Billing overview.	example-bucket
   Bucket Subdirectory	Specify an absolute path as the subdirectory in the bucket. If you leave this parameter empty or set this parameter to /, the root directory of the bucket is mounted.	/files
   OSS Endpoint	Specify an endpoint. By default, the endpoint of the bucket is used. You can select Custom Endpoint to specify a custom endpoint. For more information about OSS endpoints in different regions, see Regions, endpoints and open ports. Note If you select a bucket that resides in the same region as the service in Function Compute, we recommend that you use an internal OSS endpoint. If you select a bucket that resides in a different region, you must use a public endpoint. In this case, you are charged for data transferred over the Internet.	Default Endpoint
   Local Function Directory	Specify a local function directory. The directory must be a subdirectory of /home, /mnt, or /data. Note You do not need to manually create a local function directory. You can directly use an existing directory.	/mnt/oss
   Permissions on Local Function Directory	Specify permissions on the directory after the bucket is mounted to the local function directory. You can select Read-only or Read and Write.	Read and Write

   Note

   The OSS mounting feature depends on network settings of the service. If you set Access to VPC to Yes and Access to Internet to No, you must use a public OSS endpoint so that the function can access the Internet over the specified VPC. For more information, see Configure static public IP addresses.

Step 2: Create a function and write code to access the mounted OSS directory

After you mount an OSS bucket, you can perform the following steps to access files in the mounted OSS directory in a way similar to accessing on-premises files:

1. In the Create Function page, configure the following parameters. Retain the default values for other parameters and click Create.

   • Method to create the function: Use Built-in Runtime.

   • Basic Settings: Configure Function Name and set Handler Type to Event Handler.

   • Code: Set Runtime to Python 3.10 and Code Upload Method to Use Sample Code.

2. On the function details page, click the Code tab, write code in the code editor, and then click Deploy.

   The following sample code provides an example on how to write function code in Python:

   import os
   
   
   def handler(event, context):
       # Mounted directory.
       mount_path = '/mnt/oss'
       
       # List files in the mounted directory.
       files = os.listdir(mount_path)
       print("Files in OSS mount:", files)  
       # Read a file in the mounted directory.
       file_path = os.path.join(mount_path, 'example.txt')
       if os.path.exists(file_path):
           with open(file_path, 'r') as file:
               content = file.read()
               print("Content of example.txt:", content)
       else:
           print("example.txt does not exist.")
       # Write a file to the mounted directory.
       write_path = os.path.join(mount_path, 'output.txt')
       with open(write_path, 'w') as file:
           file.write("Hello, OSS mount!")
           print("Wrote to output.txt in OSS mount.")
       
       return "Function execution completed."
     

   Note

   Replace example.txt with the name of an existing file in the mounted directory.

3. After the code is deployed, click Test Function on the Code tab.

   After the execution is complete, you can view the execution result in the lower part of the Code tab. On the Log Output tab, you can view the content of the file that is read (in this example, example.txt) in the directory. You can also view the content of the file that is written (in this example, output.txt) in the directory.

Check the storage class of the OSS bucket that you configured. If the storage class is Archive or Cold Archive, all objects stored in the bucket are frozen and be accessed only after they are unfrozen. We recommend that you set the storage class of the OSS bucket to Standard.