Application Load Balancer (ALB) is a CLB service provided by Tencent Cloud that focuses on Application-layer protocols such as HTTP, HTTPS, and QUIC. It offers powerful Application layer traffic processing and auto scaling capabilities. ALB supports advanced routing based on request content, distributes access requests from clients to backend servers according to configured forwarding policies, and is deeply integrated with cloud-native services such as containers and microservices. It can be used as a cloud-native Ingress gateway and is suitable for business scenarios such as audio and video, live streaming, gaming, microservice communication, and large model AI.
You can debug the product API online through API Explorer, or see API overview to learn about all API capabilities. ALB supports creation and management through multiple methods such as the console, SDK, and Terraform.
Common terminology for application CLB API interfaces is shown in the table below:
| Terminology | Description |
|---|---|
| Instance (LoadBalancer) | A physical resource oriented to layer 7 (application layer) that provides load balancing capacity. It is the basic unit for handling listeners, forwarding rules, and backend services. |
| Listener | The minimum business unit of ALB. It requires protocol (HTTP/HTTPS/QUIC) and port configuration to receive and handle client requests. |
| Forwarding Rule | Defines request routing. Forwarding is supported based on conditions such as domain name, path (URL), HTTP headers, Cookie, request method, and source IP. Advanced operations such as redirection and rewrite are also supported. |
| Target Group | A logical group of real servers that contains a group of backend services for processing actual requests. It supports multiple types such as CVM, container, and ENI. |
| Health Check | Periodically probe the availability of real servers, auto-isolate unhealthy nodes, and ensure business continuity. Supports customizable check parameters and health check templates. |
| VIP | The entry IP for traffic distribution, which is a private IP address within the VPC and the physical address entity through which ALB provides external services. |
| Public/Private ALB | A public ALB provides services through Elastic IPs (EIPs), while a private ALB provides services only within a VPC. |
| EIP (Elastic IP) | A public IP address that can be applied for independently and dynamically bound to an ALB instance. Only public ALBs need to be bound. It supports flexible unbinding and migration to access a public network. |
| Domain Name | Resolve to the ALB instance address. Both public and private network ALBs can be used. Public network ALBs resolve to EIPs, and private network ALBs resolve to VIPs. ALB domain names cannot be accessed directly. You need to use a CNAME to resolve your self-owned domain name to the ALB domain name for seamless access. |
| Bandwidth Package | Provides region-level public network bandwidth sharing and reuse. Multiple ALB instances (or EIPs) can share one bandwidth package, allocate bandwidth on demand, and reduce public network bandwidth costs. |
For API parameter limits, refer to the parameter description and quota description in each API document. Other limits are as follows:
| Restriction item | Description |
|---|---|
| Destructive operation | Operations such as Delete, Destroy, Isolate, and Remove are irreversible. Proceed with caution. |
| Authentication method | The tenant-side API performs resource-level authentication through CAM to ensure the calling account has the corresponding operation permission on the target resource. |
Take creating an ALB instance as an example to quickly experience the ALB API call process:
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