Link IoT Edge:Access Alibaba Cloud OSS

1. Create an OSS bucket

1. For more information about how to create a bucket, see Create an OSS bucket. The following table describes parameters to be configured. For other parameters that are excluded in the table, you can use default values.

   Parameter	Description
   Bucket Name	Enter le-fc-bucket.
   Region	Select the data center where the bucket resides from the drop-down list. You can select a data center that is close to your location to improve the access speed.

2. Create an on-premises file named ossCloudFile.txt, edit the file based on your needs, and upload the file to the le-fc-bucket bucket. For more information about how to upload files to buckets, see Upload objects.
   The ossCloudFile.txt file is used for subsequent testing when you use a function to download OSS files.

2. Create a function to access OSS

1. Download the following package of the function. The function is used to upload on-premises files to and download files from OSS.
   accessAliOSS-code.zip
2. Log on to the Function Compute console.
   If you have not activated Function Compute, read the terms, select I have read and agree, and then click Activate Now.
3. Optional. In the left-side navigation pane, click Services and Functions. On the Services and Functions page, click Create Service. On the Create Service page, set the parameters as required and click Submit.
   The Service Name parameter is required. In this example, the Service Name parameter is set to EdgeFC. You can set other parameters based on your needs.

   Note If the EdgeFC service has been created for other scenarios or applications, you do not need to recreate the service.
4. After you create the service, you must create a function in the service. On the Services and Functions page, click Create Function. On the Create Function page, click Configure and Deploy in the Event Function section.
5. Configure the following parameters of the function.

   Parameter	Description
   Service Name	The service where the function resides. Select EdgeFC.
   Function Name	Enter accessAliOSS.
   Runtime	The runtime environment of the function. Select nodejs8.
   Function Handler	The handler of the function. Use the default value index.handler.
   Memory	The size of memory that is required to execute the function. Select 512MB.
   Timeout	The timeout period of the function. Enter 10. Unit: seconds.
   Single Instance Concurrency	The number of concurrent requests that can be processed by an instance. Use the default value.

   You can set other parameters based on your needs or leave them unspecified. For more information, see What is Function Compute?

   Confirm the function parameters and click Create.

6. After the function is created, the function details page appears. Click the Code tab. On this tab, select Upload Zip File and click Select File to upload the accessAliOSS-code.zip package that you downloaded in step 1. Then, click Save.
   After the code is uploaded, you can modify the source code on the In-line Edit tab.

   Edit the code as follows:

   • Replace <Your OSS Region> with the region that you selected when creating the bucket in 1. Create an OSS bucket. You can view the region on the Overview page of the OSS console.
   • Replace <Your OSS Bucket> with the bucket name le-fc-bucket that you specified when creating the bucket in 1. Create an OSS bucket.
7. Log on to the gateway that has been created in Prerequisites and run the following command to generate an on-premises file named localFile.txt that is used to test the uploading feature.

   sudo echo "Hi, this is the file from edge GW." > /linkedge/run/localFile.txt

   Note When you use Function Compute code to access files of the gateway host, you must note the limit on the file path. If you use Link IoT Edge Standard Edition, Function Compute code runs in a file system that is isolated from the host. Function Compute only shares the /linkedge/run directory with the host environment and is authorized to read and write this directory. Therefore, you must specify /linkedge/run for the path of the test file.
8. Go to the Function Compute console and find the accessAliOSS function. On the Code Management page, click Save and Invoke.
9. Optional. To download OSS files, you must go to the function details page to modify the sample code of accessAliOSS. Choose Code > In-line Edit. In the code editor, go to line 45 to remove the client.put method, go to line 48 to remove the // character, and use the OSS SDK to call the following method: client.get('ossCloudFile.txt', "/linkedge/run/fileFromCloud.txt");.
   ossCloudFile.txt indicates the file that is uploaded to the le-fc-bucket bucket, and /linkedge/run/fileFromCloud.txt indicates the file that is downloaded from Alibaba Cloud to the edge side.1. Create an OSS bucket

3. Assign the function to the edge instance

Assign a RAM role that is attached with the AliyunOSSFullAccess RAM policy to the edge instance. Alternatively, you can attach the AliyunOSSFullAccess RAM policy to a role that the edge instance is authorized to assume. For more information about how to enable the edge instance to manage other Alibaba Cloud resources, see Access resources of other Alibaba Cloud services.

1. In the left-side navigation pane, click Applications.
2. Create a Function Compute-based edge application from the function that is created in step 2: Create a function to access OSS. For more information about how to create a Function Compute-based edge application, see Use Function Compute to create edge applications.

   The following table describes the application parameters.

   Parameter	Description
   Application Name	The name of the application. Example: accessAliOSS.
   Application Type	Select Function Compute.
   Region	Select the region where the service is deployed.
   Service	Select EdgeFC.
   Function	Select accessAliOSS.
   Authorization	Select AliyunIOTAccessingFCRole.
   Application Version	The version of the application. You must specify a unique version number for a single application.

   The following table describes the function parameters.

   Parameter	Description
   Running Mode	Two running modes are available. In this example, select Continuous. The application runs immediately after being deployed.
   Memory Limit (MB)	The maximum memory that is available for running the function. Unit: MB. Enter 512. If the memory that is used by the function exceeds the limit, the Function Compute application is forced to restart.
   Timeout Limit (Seconds)	The maximum processing period after the function receives an event. Use the default value 5. If the function does not return the result within the specified period, the Function Compute application is forced to restart.
   Scheduled Execution	Turn on the Scheduled Execution switch and enter * * * * * in the text box. The CRON expression indicates that the function is scheduled to run every minute. For more information about CRON expressions, visit the CRONTAB website.

   You do not need to specify other parameters.

3. In the left-side navigation pane, click Edge Instances.
4. Find the created edge instance and click View in the Actions column.
5. On the Instance Details page, click the Configurations tab. On this tab, click Add Role & Permission to assign the AliyunIOTAccessingFCRole role to the edge instance. Click OK.
6. On the Instance Details page, click the Edge Applications tab. On the Edge Applications tab, click Assign Application.
7. Assign the accessAliOSS function to the edge instance, and click Close.

4. Deploy the edge instance

1. On the Instance Details page, click Deploy in the upper right corner. In the message that appears, click OK to assign resources such as sub-devices and Function Compute-based edge applications to the edge instance.
2. Wait about one minute after the instance is deployed and go to the OSS console. Choose le-fc-bucket > Files to view the fileFromEdge.txt file that has been uploaded.
   In the Actions column, choose More > Download to save the file on your computer.

   You have completed the procedure of using Function Compute to access Alibaba Cloud OSS.