Serverless App Engine (SAE) supports binding a Classic Load Balancer (CLB) instance to your application to control how it receives traffic. Bind an Internet-facing CLB instance to expose the application to the Internet, or bind an internal-facing CLB instance to allow communication with other applications in the same virtual private cloud (VPC).
Before binding a CLB instance, review the following constraints to avoid misconfiguration or accidental data loss.
CLB access modes
| Mode | Description |
|---|---|
| Internet-facing | Exposes your application to the Internet. Bind an Internet-facing CLB instance to the application. |
| Internal-facing | Enables communication with other applications in the same VPC. Bind an internal-facing CLB instance to the application. |
For background information on CLB, see CLB documentation.
Limitations
Listeners configured in SAE cannot be modified in the CLB console
SAE instances run as non-Elastic Compute Service (ECS) containers that are stateless and replaced frequently. Each time you deploy or restart an application, SAE resets the configurations of the application. Any changes you make to that listener directly in the CLB console are overwritten by SAE's default configuration and any custom settings you defined in SAE.
To change a listener configuration, make the change in SAE, not in the CLB console.
Deleting an access configuration releases the CLB instance
If you delete the access configuration of a CLB instance that was purchased through SAE, SAE releases the CLB instance immediately. This action cannot be undone — the instance cannot be repurchased.
Before deleting an access configuration, record the CLB instance ID and its listener settings in the CLB console. If similar purchase and recycling behaviors exist in other services, proceed with caution when using existing CLB instances. To avoid accidental release, purchase CLB instances directly in CLB or through SAE, and keep a record before making any deletion.
Shared-resource CLB instances are not supported
SAE does not support shared-resource CLB instances.
Other limits
For additional CLB limits, see Limits.