The Doppler Quarterly Special Edition 2019 | Page 50

Enabler #3 - A Prescriptive Migration Plan with Attention to Details Once an application analysis determines the application is suitable for migration and its migration patterns are known, you need to develop a detailed migration plan. Besides the overall goal of the migration, a migration plan should include execution level details, including all migration tasks and owners. The execution level details will vary based on the chosen migration pattern. For example, a Rehost pattern will mainly have infrastructure tasks with few application configuration changes, as well as a test and validation plan. A Refactor pattern migration effort will need to include details on each of the components to be changed, including its current and future state, functionality, accompanying code, deployment details, and test and val- idation plans. At a minimum, the migration plan should include the following: • Business drivers and expectations • Functionality • Current and future state architecture • Patterns and approach • Asset list, dependencies • Desired configuration or changes • Tools (migration, deployment, monitoring, logging) • Detailed migration tasks, deployment plans with RACI • Readiness, test, validation, cutover and operations plans For migration efforts to achieve the desired velocity and scale, the migration plan for exe- cution needs to be very prescriptive. In addition, reusable approaches and artifacts and self-service approaches for different stakeholders will greatly help reduce latency. In the process of creating a detailed migration plan, one should account for approaches that reduce the amount of downtime required for cutover during a migration effort. You can use various approaches to achieve close to zero downtime for an application migra- tion, including: blue/green deployments, incremental replication, isolated environment for testing and validation before cutover, or temporary DNS records for testing. For example, you can develop standard migration checklists for each of the patterns, which you can reuse across all applications. As many organizations have a common set of tools for testing and validation, a common set of tests across patterns is useful to the operations team for onboarding applications at the desired velocity. 48 | THE DOPPLER | SPECIAL EDITION 2019