Compute Nest allows users to upgrade service instances. If you want to fix issues that exist in a service of previous versions or release new features for the service, you can publish the service of a new version. After you publish the service of a new version, your customers can upgrade the service instances that are created based on the service of previous versions based on their business requirements. The upgraded service instances support the features of the service of the new version.
How it works
A service can be updated by using a stack or an application. The following sections describe how to update a service.
Update a service by using a resource stack
When a customer creates a service instance in Compute Nest, a stack is created based on a service template provided by Resource Orchestration Service (ROS). When the service is updated, the stack is updated based on the ROS template that is used to update the service. This way, cloud resources and software applications can be upgraded at the same time. If you update a service by using a stack, you need to only define different versions of the service. During the update, Compute Nest compares the differences between the ROS templates of the two versions and performs the corresponding update operations.
The following example shows how to update a service by using a stack. In this example, a service has two versions named V1 and V2. The service template of V1 includes the definitions of Resource A, Resource B, and Resource C. The service template of V2 includes the definitions of Resource A, Resource B, and Resource D. The definition of Resource A remains unchanged, and the property of Resource B changes. The following figure shows the update process.
The following rules for updating a service by using a stack are summarized based on the preceding figure:
If a resource that is defined in the service template of an earlier version is the same as that defined in the service template of the later version, the resource remains unchanged. In this example, Resource A remains unchanged.
If a resource that is defined in the service template of an earlier version is the same as that defined in the service template of the later version, the resource is updated. In this example, Resource B is updated.
If a resource that is defined in the service template of an earlier version does not exist in the service template of the later version, the resource is deleted. In this example, Resource C is deleted.
If a resource that is defined in the service template of the later version does not exist in the service template of an earlier version, the resource is created in the service template of the later version. In this example, Resource D is created.
Update a service by using an application
Applications can be updated based on CloudOps Orchestration Service (OOS). OOS runs script commands on Elastic Compute Service (ECS) resources in service instances to replace ECS images or software packages. This way, software applications in service instances are updated by performing O&M operations instead of directly modifying the stack. This method is suitable for updating software applications in ECS-based deployment scenarios and is not applicable to Container Service for Kubernetes (ACK)-based deployment scenarios.
To update an application, customers must compare the earlier and later service versions and configure the required actions provided by OOS for the update. OOS performs the configured actions on the service instance of the earlier version to update the service. Customers need to perform more complex configurations in this method.
Applications are not updated on the stack and the update operation is imperceptible to the stack. In this case, if other update operations are performed on the stack, this update operation may be overwritten. Therefore, we recommend that you update a service by using a stack instead of an application.
Service instance upgrade rules
The version to which you want to upgrade a service instance must be available to the service instance.
A service instance can be upgraded only from an earlier version to a later version.
A service provider can upgrade a service instance from a version to the draft version or beta version within the same account that is used to publish the service and create service instances in a test.
The draft version is the latest version and cannot be upgraded.
The beta version is the second latest version, which can be upgraded to the draft version. A published version can also be upgraded to the beta version.
Service instance upgrade
You can upgrade a single service instance or multiple service instances at a time. For more information, see Upgrade one or more service instances.
Upgrade a single service instance on the service details page.
Upgrade multiple service instances at a time on the O&M Management tab of the details page of the service.
Service instance rollback
Service rollback is the reverse operation of service instance upgrade. If you perform a rollback operation on a service instance, Compute Nest rolls back a service instance from a later version to an earlier version. Customers can roll back a service instance to its previous version. Customers can view the version to which a service instance can be rolled back by viewing the service update history.