Migrating from Tailor to Helm

Scope and Goal of this document

Tailor has been developed for OpenShift 3.11. Back in the days, Helm required the use of a privileged Tiller service and did not work well with OpenShift-specific resources. With Helm 3 and OpenShift 4, this situation as changed.

While Tailor also works in an OpenShift 4 cluster, OpenShift has integrating Helm into its product, and Helm has a huge and growing community. Therefore, it is recommended to use Helm instead of Tailor in an OpenShift 4 cluster.

This document will describe how to migrate from Tailor to Helm.

Tailor is based on OpenShift templates, which define the Kubernetes resources to apply. Helm uses a different templating language / engine, but in the end the templates also describe Kubernetes resources. Therefore, migration effort is relatively low as one only needs to change the syntax of the definition, not the definition itself. Further, there are differences between the CLI of the two tools and not all features of Tailor are available in Helm and vice-versa. Once migration to Helm is complete, it is also recommended to look at the best practices in the Helm community and adopt these.

Migrating templates

There are basically two options how to approach this: you can either convert your existing OpenShift templates to chart templates, or you can start with a blank chart and fill in the gaps.

Converting OpenShift templates

If you want to convert your existing templates, you may use template2helm. This method should require less effort, but you are left with a template that might have some errors and does not follow best practices from the Helm community.

Example usage:

template2helm convert -t openshift/template.yml -c . # Will create a "chart" folder in .

Starting with a blank chart

The other option is to start from a blank chart and adjust this as necessary to match the live configuration. This will almost certainly be more effort than converting the templates, but you will learn more about Helm templating and can start out with some best practices.

Example usage:

helm create chart