Rehost VMs with Forklift

Have you ever thought of climbing Mt. Everest? When you have hundreds of legacy VMs on your cloud-native journey, you might feel just as daunted. In this blog, I’ll be introducing an open-source tool Forklift that helps mass migration of hundreds of VMs. Forklift leverages another popular open-source tool called KubeVirt to help you set up the basecamp and prepare you on your way to the summit.

How Forklift fits into the overall Konveyor landscape

Forklift is part of the larger Konveyor umbrella community. Once you assess/analyze your existing applications and workloads using Tackle, Forklift helps on the rehosting bit, with the applications or components that are not so easy to containerize, by providing a VM migration solution. Using Forklift, you can either migrate VMs to KubeVirt on Kubernetes, or to OpenShift making use of its Virtualization capabilities.

An architectural diagram for the Konveyor project

How Forklift works

Installed as an operator, Forklift is targeted to Kubernetes, and the Red Hat supported downstream Migration Toolkit for Virtualization is targeted to OpenShift. Once it is installed, it can be used through the UI or consumed/automated via CLI or API. The first step is to add the “providers” which means specifying the sources of the VMs and their destination(s). For example, you can add a VMware provider by entering the hostname or IP address, username/password, and certificate SHA1 fingerprint. If the credentials are valid, this will create a source endpoint showing all the clusters, hosts, VMs, and their networks/datastores.

Once you’ve added the source and target providers, you can directly create a migration plan and specify the network and storage mappings on the fly. According to the following diagram, you can manually create the network and storage mappings as well. If you’re using Forklift for the first time, you might try the first approach for ease. During mapping, your source VM networks will be mapped to pod networks in the target cluster/namespaces. The source datastores will be mapped to target cluster storage classes. This way, we create equivalences between the resources in the source provider and the target provider, enabling the possibility to mass migrate VMs. The final step is to create a migration plan and specify a set of VMs that you are migrating over.

A block diagram on how Forklift operates

Once the migration plan is run, you will have a new instance of the VMs in the target platform, while keeping the original ones in the source as a rollback mechanism.