1. Scenarios of different instances
Shared instance (VPC): Tenants share the same outbound IP address and bandwidth. Therefore, each tenant is prone to the interference from other tenants. This instance type is more suitable for development testing, evaluation, and small-scale production.
Dedicated instance (VPC): To obtain a higher-level guarantee in the service level agreement (SLA), you can purchase a specification that contains higher requests per second (RPS) to use dedicated resources. The resources include inbound public IP addresses, IP addresses for virtual private clouds (VPCs), outbound Internet bandwidth, and isolated server clusters.
2. Migration procedure
In the left-side navigation pane of the API Gateway console, choose Manage APIs > API Groups. Click the API group that you want to migrate. On the Group Details page, click Modify Instance for API Group Deployment. In the dialog box that appears, select a destination instance from the Destination Instance drop-down list, read the precautions, select I have read the preceding statement and know the potential risks associated with the migration, and click Migration. The migration immediately takes effect on the Domain Name System (DNS) of the second-level domains of API Gateway. The migration takes effect on your API group about 1 to 10 minutes later based on the DNS cache.
If you are using a dedicated instance whose specification cannot meet your business requirements, you can upgrade the instance to a higher specification. For more information, see Change an instance specification.
Note: Due to DNS cache, some requests are sent to the previous instance after the migration. Make sure that all requests are forwarded to the new instance before you release the previous instance.
3. Migration notes
If you need to migrate an API group for which you have changed the RPS, submit a ticket. Before you migrate an API group, check each of the following technical details about the differences before and after migration.
3.1 Migrate an API group from a shared instance (VPC) to a dedicated instance (VPC)
After you migrate an API group to a dedicated instance, the maximum RPS and the HTTPS security policy of the destination dedicated instance apply to the API group.
The outbound IP address of an API Gateway instance may change. You can go to the Instances page to view the outbound IP address. Make sure that the outbound IP address of the API Gateway instance is included in the whitelist of IP addresses that are allowed to access the backend service.
If specific features are enabled for your API group, make sure that the same features are enabled for the destination instance before you migrate your API group. Specific features for an API group include the second-level domain name for access over VPCs, the internal domain name for API calls from API Gateway, inbound IPv6 traffic, and outbound IPv6 traffic.
If the destination instance is a VPC integration instance, make sure that the IP address or CIDR block of the backend service is allowed by the security group of the Elastic Network Interface (ENI) that is bound to destination instance.
3.2 Migrate an API group from a dedicated instance (VPC) to another dedicated instance (VPC)
After you migrate an API group to a dedicated instance, the maximum RPS and the HTTPS security policy of the destination dedicated instance apply to the API group.
The outbound IP address of an API Gateway instance may change. You can go to the Instances page to view the outbound IP address. Make sure that the outbound IP address of the API Gateway instance is included in the whitelist of IP addresses that are allowed to access the backend service.
If specific features are enabled for your API group, make sure that the same features are enabled for the destination instance before you migrate your API group. Specific features for an API group include the second-level domain name for access over VPCs, the internal domain name for API calls from API Gateway, inbound IPv6 traffic, and outbound IPv6 traffic.
If the destination instance is a VPC integration instance, make sure that the IP address or CIDR block of the backend service is allowed by the security group of the ENI that is bound to destination instance.