Using Helm with Tilt

Tilt supports Helm out-of-the-box.

There are two ways you can use Helm charts with Tilt.

  • Install a remote Helm chart from the rich library of existing charts.

  • Iterate on a local Helm chart that you’re building.

Let’s dig into each one.

Remote charts

The helm_remote extension lets you load from a library of existing charts.

Here’s an example that deploys the stable/mysql chart:

# Tiltfile

load('ext://helm_remote', 'helm_remote')
helm_remote('mysql',
            repo_name='stable',
            repo_url='https://charts.helm.sh/stable')

Visit Artifact Hub to find Helm charts for many off-the-shelf tools. They each list the repo URL and chart name to use with helm_remote.

To customize the chart with your own values.yaml settings, see the helm_remote README for additional options to configure the chart.

Local charts

The helm built-in function lets you load from a chart on your filesystem.

Calling helm() runs helm template on a chart directory and returns a blob of the Kubernetes YAML rendered by Helm:

k8s_yaml(helm('./charts/my-chart'))

When you make edits to the files in the chart directory, Tilt will automatically re-deploy the chart.

Helm Options

The helm function has a few options for common arguments:

yaml = helm(
  'path/to/chart/dir',
  # The release name, equivalent to helm --name
  name='release-name',
  # The namespace to install in, equivalent to helm --namespace
  namespace='my-namespace',
  # The values file to substitute into the chart.
  values=['./path/to/chart/dir/values-dev.yaml'],
  # Values to set from the command-line
  set=['service.port=1234', 'ingress.enabled=true']
  )
k8s_yaml(yaml)

Sub-charts and requirements.txt

If you have chart dependencies, you need to run:

helm dep update

outside of Tilt to download the dependencies to your repo. Then create a .tiltignore with the contents:

**/charts
**/tmpcharts

Or, if you want be more cautious:

path/to/your/chart/charts
path/to/your/chart/tmpcharts

When Helm runs, it touches these chart directories. Adding these lines ensures that Tilt doesn’t reload the Tiltfile every time Helm touches them.

Advanced Helm

Helm can also do more advanced templating – like downloading remote charts and injecting run-time variables.

Fortunately, Tilt has a plugin API. You can tell it how to shell out to other build and deploy tools.

The plugin API has two important functions:

  • local() for running local shell commands

  • watch_file() for telling Tilt to reload its configuration when a file changes

Let’s take a look at some common recipes for using the plugin API with Helm.

Example Repo

If you prefer to play with a code sample, see

tilt-dev/tilt-helm-demo

Re-implementing the helm() built-in

To start, let’s try implementing the helm() built-in ourselves.

k8s_yaml(local('helm template path/to/chart/dir'))
watch_file('path/to/chart/dir')

The real helm() built-in handles some extra optimizations and edge cases, but that’s basically all it does!

Passing a single variable

Now that we know how to shell out to helm, we can pass arbitrary flags. Let’s try using --set to set a variable.

k8s_yaml(local('helm template --set key1=val1,key2=val2 path/to/chart/dir'))
watch_file('path/to/chart/dir')

Passing a values file

If you’re passing a lot of variables, it’s usually better to put those in a values.yaml file.

k8s_yaml(local('helm template -f ./values.yaml path/to/chart/dir'))
watch_file('path/to/chart/dir')
watch_file('values.yaml')

Other Helm tools

There are other helm tools like helmfile for working with Helm charts.

We can use the same plugin commands to implement those as well. In this example, we factor out helmfile into a helper function.

# Helper function to read K8s config YAML from helmfile.
def helmfile(file):
  watch_file(file)
  return local("helmfile -f %s template" % file)

# Tell Tilt to apply to k8s config generated by helmfile.
k8s_yaml(helmfile("k8s/staging/helmfile.yaml"))

You can try out this example yourself in this example repo.

Further customization

If you have a Helm use-case that’s not covered here, we’d love to hear about it!

You can file an issue on GitHub.

We’re also active on the Kubernetes slack in the #tilt channel. Get an invite at slack.k8s.io.

 
 
 

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