Server Load Balancer:Add Function Compute as a backend for ALB

Key features

• Serverless architecture support: Use Function Compute as a backend service for ALB to easily build serverless applications and reduce operational costs.

• Auto scaling: Function Compute automatically scales computing resources up or down based on traffic, ensuring sufficient computing capacity during peak hours and saving resources during off-peak periods.

• High availability and fault tolerance: ALB and Function Compute work together to provide high availability and disaster recovery, ensuring your application runs stably.

Use cases

• Microservices: Use the advanced routing capabilities of ALB to distribute requests to different microservice functions. Function Compute scales dynamically to handle high-concurrency requests, improving system elasticity and reliability.

• Real-time data processing: ALB distributes data processing requests to the appropriate functions. Function Compute then processes the data in real time with only a few lines of code and simple configuration.

• Event-driven architecture: ALB receives event-triggered requests and forwards them to the corresponding functions. Function Compute processes the events and stores the results in a database or sends them to other services, enabling dynamic, event-driven processing.

• Image and video processing: ALB receives image or video upload requests and distributes them to the appropriate processing functions. Function Compute provides elastic compute resources that scale automatically based on the task, ensuring efficient task completion.

Limitations

• You can use Function Compute as a backend service only in specific regions. For a list of supported regions, see Regions where ALB supports Function Compute as a backend service.

• The ALB instance and the function must be in the same region.

• A Function Compute server group supports only one function.

• For Function Compute 2.0, if the Handler type is set to Event handler, you must configure an HTTP trigger to associate the function with an ALB instance.

Step 1: Create a function

1. Log on to the Function Compute console. In the left-side navigation pane, choose Function. On the Function page, select a target region, and then click Create Function.

2. On the Create Function page, select a function type, configure the function code, and then click Create.

   This topic provides an example of an Event Function where the Code uses the default Use Sample Code. You can keep the default values for other event function parameters or modify them as needed.

   

   

3. On the function details page, on the Code tab, click Test Function.

   After the function runs successfully, you can view the result in the Response area. In this example, the result is hello world.

Step 2: Create a Function Compute server group

1. Log on to the Application Load Balancer console. In the left-side navigation pane, choose Server Groups. Select the target region from the top navigation bar, and then click Create Server Group.

2. In the Create Server Group dialog box, select Function Compute for Server Group Type, and then click Create.

   Important

   If you enable health checks for the ALB instance, Function Compute counts the probes as requests, which incurs charges. For more information, see Billing.

   

3. In the The server group is created dialog box, click Add Backend Server.

4. In the Add Backend Server panel, select the function you created, and then click OK.

   In this example, Configuration Method is set to Service, the function you created is selected for Function Name, and Specified Version is set to LATEST. If you need to configure the function by using its ARN, select ARN for Configuration method. You must first obtain the function ARN.

   

Step 3: Configure a listener

1. In the left-side navigation pane, choose ALB > Instances, and then click the ID of the target instance.

2. Click the Listener tab, and then click Create Listener.

3. On the Configure Listener page, configure the listener protocol and port, and then click Next.

   This example uses the HTTP protocol and port 80. You can keep the default values for other parameters or modify them as needed. For more information, see Add an HTTP listener.

   

4. In the Server Group configuration wizard, from the Server Group drop-down list, select Function Compute, select the target server group, and then click Next.

   

5. On the Configuration Review page, confirm the settings and click Submit.

Step 4: Configure domain name resolution

For production environments, we recommend using a custom domain name and creating a CNAME record to point it to the domain name of the ALB instance.

1. In the left navigation bar, select ALB > Instances, and on the Instances page, copy the DNS name of the created ALB instance.

2. Follow these steps to add a CNAME record:

   1. Log on to the Alibaba Cloud DNS console. Find your custom domain name and click Settings in the Actions column.

      Note

      If your domain name was not registered with Alibaba Cloud, you must first add it to Alibaba Cloud DNS before you can configure its DNS settings.

   2. On the DNS settings page, click Add Record. Configure the CNAME record and then click OK.

      For this example, set Record Type to CNAME and Record Value to the DNS name of your ALB instance. You can keep the default values for other parameters or modify them as needed. For more information, see Add a DNS record.

      

Step 5: Test connectivity

After you complete the preceding operations, a connection is established between ALB and Function Compute. You can open a command-line window and run the curl <custom domain name> command to test the connectivity between ALB and Function Compute.

If you receive a response message as shown in the following figure, it indicates that ALB can forward requests to Function Compute and invoke the function.