Publishing and Deploying Helm Charts using GitLab#

Helm charts provide a powerful ability to template manifests, making it easy to deploy multiple instances of an application (e.g., to support feature-branch deployments).

This guide isn't going to talk about how to actually write a Helm chart, as there are several other guides available to do this.

Publishing your Chart in GitLab#

To publish a chart in GitLab, you can leverage a CI template that we've built. In your repo, create a .gitlab-ci.yml file with the following contents:

include:
  project: it-common-platform/tenant-support/ci-templates
  file: building-blocks/helm.yml

stages:
  - deploy

Deploy chart:
  extends: .helm-publish
  rules:
    - if: '$CI_COMMIT_BRANCH && $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH'
      changes:
        - Chart.yaml

This will extend one of our "building blocks" and deploy the chart anytime the Chart.yaml file is updated.

Deploying a chart not at the root of your repo#

If you need to deploy a chart that's nested in your repo, you can set the HELM_CHART_LOCATION. This value defaults to the root of your repo.

Deploy chart:
  extends: .helm-publish
  variables:
    HELM_CHART_LOCATION: chart/path

Deploying your Chart on the Platform#

Once you have a chart published, you can deploy it using Flux's Helm Release support. With Flux, we need to define a source (the HelmRepository) and a reconciler (the HelmRelease which actually defines how and where the chart should be deployed).

If your chart is part of a private or internal project in GitLab, you will need to provide Flux with credentials to fetch the chart.
1. Go to Settings -> Repository -> Deploy tokens and generate a new deploy token. You can give it any name, but it must have the read_package_registry permission.
2. Open the directions for Creating Sealed Secrets.
3. Create a secret named helm-chart-credential. Specify one key/value pair with a key of username and a value of the deploy token username. Create another with a key of password and value of the deploy token secret.
4. Copy the generated manifest into your tenant repo.

Now, in your manifest repo, you can define your HelmRepository. You will need your GitLab project ID, which is accessible on the project's home page. Swap that into the URL below

apiVersion: source.toolkit.fluxcd.io/v1
kind: HelmRepository
metadata:
  name: gitlab
spec:
  url: https://code.vt.edu/api/v4/projects/<gitlab-project-id>/packages/helm/stable
  interval: 5m
  secretRef: 
    name: helm-chart-credential

When you add that, you can use Headlamp or query using kubectl to see the object.

kubectl get helmrepositories -n <your-tenant-namespace>

And you'll see output similar to the following:

NAME       URL                                                             READY   STATUS                                                                               AGE
tenant-app   https://code.vt.edu/api/v4/projects/8107/packages/helm/stable   True    Fetched revision: e149da53ec05d971e5400843c8f78f427476985f490b840c7ca00c8bdfc00204   36d

From there, you can define a HelmRelease that will deploy the chart into your tenant namespace!

apiVersion: helm.toolkit.fluxcd.io/v2
kind: HelmRelease
metadata:
  name: tenant-app
spec:
  chart:
    spec:
      interval: 5m0s # The rate at which the source (HelmRepository) will be checked for updates
      sourceRef:
        kind: HelmRepository
        name: tenant-app
      chart: tenant-app
      version: 0.20.0
  interval: 5m0s # The rate at which the controllers attempts to reconcile the release
  releaseName: tenant-app
  # values:
  #   key: any custom values you want to override from the chart

Once defined, you can query the HelmRelease using Headlamp or kubectl. Currently, we have two versions of HelmReleases defined, so we have to be a little more explicit in which version we want to fetch.
```
kubectl get helmreleases.helm.toolkit.fluxcd.io -n <your-tenant-namespace>
```
And you'll see output like the following:
```
NAME       READY   STATUS                             AGE
tenanat-app   True    Release reconciliation succeeded   36d
```

Flux Service Accounts#

.spec.serviceAccountName, the variable which sets which Service Account flux uses to deploy assets, is an optional field for tenants. A default privileged service account for your namespace named flux is provided and will automatically be added when undeclared.

Additional Resources#

The Flux docs have quite a few guides on using Helm charts. Links are available below: