Helm alternative

This is a follow-up to a great post “Think twice before using Helm”. Recently we’ve had a lot of questions about what could be an alternative to Helm. In this blog post I will try to show you an alternative.

What do we need

To download render application visit:
https://github.com/VirtusLab/render

Helm Chart that is interesting for us — can be downloaded here:
https://github.com/helm/charts

How to do it — TL/DR

Get Chart you are interested in.
Remove unneeded stuff from both directory structure and files.
Merge all templates into one — following desired resource creation order (optional but recommended).
Render the newly created template file with desired config file(s).
Commit to your VCS (optional but recommended).
Deploy to Kubernetes
Feel good!

How to do it —instructions in more details

Let’s convert a Helm Chart to plain Kubernetes manifest template. As an example we will use kube2iam Chart.
Let’s have a look what can be found in typical Chart directory:

To create valid Kubernetes manifest we only need these files:

clusterrole.yaml
clusterrolebinding.yaml
daemonset.yaml
secret.yaml
serviceaccount.yaml

and a confog file:

values.yaml

Now we can merge them into single file (ensure resource creation order as a good practice):

Next step for our newly created template file is to remove stuff that is not needed anymore. All Helm specific variables should be removed since we do not need them.

These would be variables and functions using:

Be aware that this is a quick workaround. I strongly recommend to make these changes manually so you can make sure you are not introducing any breaking changes or leaving leftovers in the template file.

Search for .Capabilities in template and remove it since this is pure Helm functionality.

{{ template "kube2iam.name" }} and {{ template "kube2iam.fullname" }} can be changed to .Name and .FullName.

Finally all configuration variables are passed without the `.Values` prefix. This means you can remove it from your new manifest template by running the following command (again, please use this command with caution and review the results):

After all modifications we get a nice and clean kube2iam.yaml.tmpl manifest template which should look like this:

Now we can render our template to a valid Kubernetes manifest:

This will output rendered file kube2iam.yaml.tmpl to kube2iam.yaml file which can be deployed to Kubernetes:

From now on, we can live a happy and prosperous Helm-free life.

Summary

Using simple rendering as a part of deployment process has a lots of benefits, but on the other hand you have to be aware of some of the more advanced Helm functionalities you lose with a simple renderer.

Pros: