Migration, integration, and validation go hand in hand as you want to do continuous validation while performing various integration with your application in the cloud.
The team starts by performing the necessary cloud functionality checks to ensure that the application is running with proper network configuration (in the desired geolocation) with some designated traffic flow. Instances can start or stop as desired when the basic cloud functionality check is complete. You need to validate that the server configuration (such as RAM, CPU, and hard disk) is the same as intended.
Some knowledge of the application and its functionality is required to perform these checks. When the primary check is complete, then you can perform integration tests for the application. These integration tests include checking integration with external dependencies and applications; for example, to make sure the application can connect to the Active Directory, Customer Relationship Management (CRM), patch or configuration management servers, and shared services. When integration validation is successful, the application is ready for cutover.
During the integration phase, you integrate the application and migrate it to the cloud with external dependencies to validate its functionality. For example, your application might have to communicate with an Active Directory server, a configuration management server, or shared services resources that are all external to the application. Your application may also need to be integrated with external applications that belong to your clients or vendors, such as a supplier receiving a feed from your APIs after a purchase order placement.
When the integration process is complete, you need to validate the integration by performing unit tests, smoke tests, and user acceptance test (UAT). The results from these tests help you get approval from the application and business owners. The final step of the integration and validation phase includes a sign-off process from the application and business owner of the application, which will allow you to cut over the application from on-premises to the cloud.
The final phase of the cloud migration factory is the cutover process. In this phase, you take the necessary steps to redirect your application traffic from the source on-premise environment to the target cloud environment. Depending on the type of data or server migration (one-step, two-step, or zero-downtime migration), the steps in your cutover process may vary. Some factors to consider when determining a cutover strategy include the following:
- Acceptable downtime for the application
- The frequency of the data update
- Data access patterns such as read-only or static data
- Application-specific requirements such as database syncs, backups, and DNS name resolutions
- Business constraints, such as the day or time during which the cutover can happen and the criticality of the data
- Changing management guidelines and approvals
Live migration is most popular for business-critical workload migration, let's learn more about it.