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Volcano Engine Function as a Service

Microservices applications

Adding CLB access configurations

This topic describes how to add a Cloud Load Balancer (CLB) access configuration for microservices apps.

Background information

If an application is accessible only through its private IP address, an application modification or restart causes a change to the private IP address, which makes the application inaccessible. Associating a CLB instance with the application enables users to access the application by using the fixed public or private IP address of the CLB instance. Additionally, the CLB instance enables load balancing among application instances and thereby effectively improves the overall application performance and stability.

Limits

A CLB configuration can be added only to an existing microservices app function. You cannot configure CLB settings when you create a microservices app function.

The CLB instance and microservices app function must be within the same virtual private cloud (VPC).

You cannot use a CLB instance that has been used by another service.

A single CLB supports up to ‌5 listener ports‌.

For CLB listener settings already configured in veFaaS, ‌manage them exclusively in veFaaS. Do not modify these settings on the CLB side to prevent conflicts.

Prerequisites

A security group has been configured. The security group needs to allow inbound traffic from source address 100.64.0.0/10 with a request protocol and target port matching the backend server port. For details, see Configuring security groups for backend servers.

A microservices app has been created and released. For details, see Creating microservices apps.

A CLB instance has been created in the same VPC as the microservices app. For details, see Creating CLB instances.

(Optional) For a public CLB, ensure that you allow inbound public traffic to container ports on the security group (except those used by a virtual CLB IP). By default, only ports 80 and 443 are open. Other ports need to be ‌explicitly configured‌.

Procedure

In the top navigation pane, select the target region.

In the left navigation bar, click Function.

In the function list, click the name of the function of the microservices app.

Click Function configuration > App access settings. Click the edit icon next to Private network CLB access address or public network CLB access address to add a CLB access configuration.

Parameter	Description
CLB instance	Select an existing CLB instance.
scheduling strategy	Select the scheduling strategy for load balancing. Weighted polling (WRR): Distributes requests cyclically according to preset instance weights. Higher-weight instances receive more traffic. This strategy features simple logic and easy implementation and is applicable to scenarios with evenly distributed requests and tiered instance performance. Weighted minimum number of connections (WLC): Routes requests to instances with the lowest ‌weight-adjusted active connections‌ (combining instance weights and real-time connection counts). This strategy is applicable to environments with volatile request loads. Source address hash (sh): Hashes the source IP address of requests to consistently route traffic to the same instance. This strategy ensures ‌session persistence‌ and is ideal for services that rely on local session state.
Select listening port	Select the listening protocol. TCP protocol: A connection-oriented transport layer protocol that supports retransmission, flow control, and congestion control, ensuring reliable and ordered data transmission. It is applicable to scenarios with high reliability requirements. UDP protocol: A connectionless transport layer protocol that does not require establishing a connection. It enables fast transmission speed without guaranteed data reliability or order, has low overhead, and is applicable to scenarios with high real-time requirements, such as video calls.
TCP protocol	This parameter is available if you select TCP protocol for Select listening port. Enter the port numbers for the CLB side and the Volcengine Kubernetes Engine (VKE) side. You can add multiple ports.
UDP protocol	This parameter is available if you select UDP protocol for Select listening port. Enter the port numbers for the CLB side and the Volcengine Kubernetes Engine (VKE) side. You can add multiple ports.

Click Add.

Last updated: 2026.08.19 14:06:07