After you create and deploy applications in the Enterprise Distributed Application Service (EDAS) console, you can upgrade the applications. If an upgraded application does not run as normal, you can roll back the application to its previous version. This topic describes how to upgrade and roll back an application.
Upgrade an application
The following table lists the upgrade policies and methods that you can use to upgrade an application in different scenarios.
|Upgrade policy||Scenario||Upgrade method||Documentation|
|Release to all at once (direct upgrade)||If an application has a small number of instances or has a simple service architecture, you can directly upgrade the application after you develop and test the application. Namely, you can directly deploy a new version of the application.||
|Phased release||If an application has a large number of instances or has a complex service architecture, you can release the application in multiple phases. The application is upgraded on only some of the instances in each phase. The phased release is complete until the application is upgraded on all the instances. If an error occurs during the phased release, you can terminate the process and roll back the application. You can release the application again after the error is fixed.||
|Canary release||A new application version needs to be verified on a small number of instances. If the verification is successful, you can upgrade the application on all instances.||Console||Use the EDAS console to implement canary releases of applications (Kubernetes)|
Roll back an application
During an application upgrade process, the application may fail to be upgraded due to exceptions, such as an unavailable deployment package and a health check failure. In this case, the application upgrade process is automatically terminated and the application is rolled back.
- Rollback during the upgrade: You can terminate the application upgrade process and roll back the application.
- Rollback after the upgrade: You can roll back the application by deploying the historical version of the application.
- Roll back an application in the EDAS console (applicable to Kubernetes clusters)
- Terminate an application upgrade process and roll back the application: AbortAndRollbackChangeOrder
- Roll back an application by deploying the historical version of the application: RollbackApplication