Seeking Guidance on Migrating CentOS 7 EC2 Instances to Amazon Linux without Downtime

Question

I'm currently managing CentOS 7 EC2 instances in our production environment, and as CentOS 7 is reaching its end-of-life, I'm exploring options for migrating these instances to Amazon Linux. My primary objective is to ensure a seamless transition without causing any downtime to our services.

Could you please provide guidance on the best approach to migrate all services and code from CentOS 7 instances to new Amazon Linux instances while minimizing or eliminating downtime?

Answer

For guidance about CentOS alternatives, you can refer to [CentOS End of Life Guidance](https://aws.amazon.com/linux/commercial-linux/centos/)

As per that page, Binary/ABI compatible options include RHEL, Rocky Linux, Alma Linux and others.

If you choose RHEL, you can refer to [Leapfrog from CentOS 7.9 to Red Hat Enterprise Linux 8.9 with Convert2RHEL and Leapp Utilities on AWS](https://aws.amazon.com/blogs/apn/leapfrog-from-centos-7-9-to-red-hat-enterprise-linux-8-9-with-convert2rhel-and-leapp-utilities-on-aws/) for the steps

Else, you can consider using [ELevate](https://almalinux.org/elevate/) to do in-place upgrade from CentOS 7.x to say Rocky Linux 8.

The in-place upgrade will take some time and may not succeed. To minimize downtime, you can consider using [AWS Application Migration Service (AWS MGN)](https://aws.amazon.com/application-migration-service/) to migrate EC2 to another EC2. MGN uses a replication agent to do continuous replication from source EC2. MGN supports [test instances](https://docs.aws.amazon.com/mgn/latest/ug/launching-test-servers.html) for testing your migration, so you can launch a test instance and test out ELevate. If successful, launch [cutover instance](https://docs.aws.amazon.com/mgn/latest/ug/launch-cutover.html) and upgrade to Rocky with ELevate to complete migration.

Seeking Guidance on Migrating CentOS 7 EC2 Instances to Amazon Linux without Downtime

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