Configuring the HelmChart Custom Resource v2

This topic describes how to configure the Replicated HelmChart custom resource version kots.io/v1beta2 to support Helm chart installations with Replicated KOTS.

Overview

To deploy Helm charts, KOTS requires a unique HelmChart custom resource for each Helm chart in the release. You configure the HelmChart custom resource to provide the necessary instructions to KOTS for processing and preparing the chart for deployment. Additionally, the HelmChart custom resource creates a mapping between KOTS and your Helm chart to allow values to be dynamically set during installation or upgrade.

For more information about the HelmChart custom resource, including the unique requirements and limitations for the keys described in this topic, see HelmChart v2.

After you complete the tasks in this topic to configure the kots.io/v1beta2 HelmChart custom resource, you can migrate any existing installations that were deployed with kots.io/v1beta1 with useHelmInstall: true to use kots.io/v1beta2 instead. For more information, see Migrating Existing Installations to HelmChart v2.

HelmChart v1 and v2 Differences

The kots.io/v1beta2 HelmChart custom resource has the following differences from kots.io/v1beta1:

HelmChart v1beta2	HelmChart v1beta1	Description
`apiVersion: kots.io/v1beta2`	`apiVersion: kots.io/v1beta1`	`apiVersion` is updated to `kots.io/v1beta2`
`releaseName`	`chart.releaseName`	`releaseName` is a top level field under `spec`
N/A	`helmVersion`	`helmVersion` field is removed
N/A	`useHelmInstall`	`useHelmInstall` field is removed

Workflow

To support installations with the kots.io/v1beta2 HelmChart custom resource, do the following:

Rewrite image names so that images can be located in your private registry or in the user's local private registry. See Rewrite Image Names.
Inject a KOTS-generated image pull secret that grants access to private images. See Inject Image Pull Secrets.
Add backup labels to your resources to support backup and restore with the snapshots feature. See Add Backup Labels for Snapshots.
Configure the builder key to allow your users to push images to local private registries. The builder key is required to support air gap installations. See Support Local Image Registries.

Rewrite Image Names

To locate images for your application in a registry, Kubernetes must have the image name and the domain of the registry. For example, you might have an image with the name example/imagename on a registry with the domain example.registry.com. For more information, see Images in the Kubernetes documentation.

During installation or upgrade with KOTS, private images stored in an external private registry are accessed through the Replicated proxy service at the domain proxy.replicated.com. Additionally, KOTS allows users to configure local registries to push images. If you use an external private registry or if your users push to a local private registry, then you must configure the HelmChart custom resource to dynamically update image names in your Helm chart. This allows Kubernetes to locate images on either the proxy service or on a user-configured local registry.

For more information:

If you use a private image registry and you do not support users pushing to local registries, see External Private Registries.
If you need to support users that push to local registries, such as users in air gap environments, see Local Registries.

External Private Registries

If you use private images with your application, then your images must be accessed through the Replicated proxy service at proxy.replicated.com/proxy/APP_SLUG/EXTERNAL_REGISTRY_IMAGE_URL, where APP_SLUG is the slug of your Replicated application and EXTERNAL_REGISTRY_IMAGE_URL is the path to the private image in your external registry. For example, proxy.replicated.com/proxy/my-app/quay.io/my-org/api.

For more information about how KOTS provides access to private images through proxy service, see About Using an External Registry.

If you use a private registry and you do not support the use of local registries for your users, then you can add a static value in the HelmChart custom resource with the location of your private image on the proxy service domain. This allows KOTS to rewrite image names in your Helm chart during installation or upgrade so that private images can be accessed through the proxy service.

Example

The following example shows a field in the values key of the HelmChart custom resource that is set to the location of the private image at proxy.replicated.com:

# kots.io/v1beta2 HelmChart custom resource
apiVersion: kots.io/v1beta2
kind: HelmChart
metadata:
  name: samplechart
spec:
  ...
  values:
    image:
    # private image accessed through the proxy service
      name: proxy.replicated.com/proxy/my-app/quay.io/my-org/nginx
      tag: v1.0.1  

The spec.values.image.name field in the HelmChart custom resource corresponds to an image.name field in the Helm chart values.yaml file, as shown in the example below:

# Helm chart values.yaml file

image:
  name: quay.io/my-org/nginx
  tag: v1.0.1

During installation, KOTS sets the image.name field in the Helm chart values.yaml file based on the value of the corresponding spec.values.image.name field in the HelmChart custom resource. Any templates in the Helm chart that access the image.name field are updated to use the location of the image on the proxy service, as shown in the example below:

apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
  - name: nginx
    image: {{ .Values.image.name }}:{{ .Values.image.tag }}

Local Registries

If you support the use of local registries for air gap or online environments, then you can use the Replicated LocalRegistryHost, LocalRegistryNamespace, and HasLocalRegistry template functions to rewrite image names in the HelmChart custom resource. When you use these template functions along with a ternary operator to rewrite image names, you ensure that images are discovered either in the user's local registry, or in your public or private registry if no local registry is configured.

The following describes the LocalRegistryHost, LocalRegistryNamespace, and HasLocalRegistry template functions:

LocalRegistryHost: Returns the host of the local registry that the user configured. For more information, see LocalRegistryHost in Config Context.
LocalRegistryNamespace: Returns the namespace of the local registry that the user configured. For more information, see LocalRegistryNamespace in Config Context.
HasLocalRegistry: Returns true if the environment is configured to rewrite images to a local registry. HasLocalRegistry is always true for air gapped installations and optionally true for online installations. You can include a ternary operator with the HasLocalRegistry template function so that KOTS uses the host and namespace of the local registry only when a local registry is configured.
For example, if the user configured a local registry and used the namespace example-namespace, then the template function '{{repl HasLocalRegistry | ternary LocalRegistryNamespace "my-org" }}/mariadb' evaluates to example-namespace/mariadb. If the user did not configure a local registry, then the template function evaluates to my-org/maridb.
For more information, see HasLocalRegistry in Config Context.

External Private Registry Example

The following example shows a field in the values key that rewrites the registry domain to proxy.replicated.com unless the user configured a local registry. Similarly, it shows a field that rewrites the image repository to the path of the image on proxy.replicated.com or in the user's local registry:

# kots.io/v1beta2 HelmChart custom resource

apiVersion: kots.io/v1beta2
kind: HelmChart
metadata:
  name: samplechart
spec:
  ...
  values:
    image:
      registry: '{{repl HasLocalRegistry | ternary LocalRegistryHost "proxy.replicated.com" }}'
      repository: '{{repl HasLocalRegistry | ternary LocalRegistryNamespace "proxy/my-app/quay.io/my-org" }}/nginx'
      tag: v1.0.1

The spec.values.image.registry and spec.values.image.repository fields in the HelmChart custom resource correspond to image.registry and image.repository fields in the Helm chart values.yaml file, as shown in the example below:

# Helm chart values.yaml file

image:
  registry: quay.io
  repository: my-org/nginx
  tag: v1.0.1

During installation, KOTS renders the template functions and sets the image.registry and image.repository fields in your Helm chart values.yaml file based on the value of the corresponding fields in the HelmChart custom resource. Any templates in the Helm chart that access the image.registry and image.repository fields are updated to use the appropriate value, as shown in the example below:

apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
  - name: 
    image: {{ .Values.image.registry }}/{{ .Values.image.repository }}:{{ .Values.image.tag }}

Public Registry Example

The following example shows a field in the values key that rewrites the registry domain to docker.io unless the user configured a local registry. Similarly, it shows a field that rewrites the image repository to the path of the public image on docker.io or in the user's local registry:

# kots.io/v1beta2 HelmChart custom resource

apiVersion: kots.io/v1beta2
kind: HelmChart
metadata:
  name: samplechart
spec:
  ...
  values:
    image: 
      registry: '{{repl HasLocalRegistry | ternary LocalRegistryHost "docker.io" }}' 
      repository: '{{repl HasLocalRegistry | ternary LocalRegistryNamespace "bitnami" }}/mariadb'
      tag: v1.0.1

# Helm chart values.yaml file

image:
  registry: docker.io
  repository: docker.io/bitnami/mariadb
  tag: v1.0.1

apiVersion: v1
kind: Pod
metadata:
  name: mariadb
spec:
  containers:
  - name: 
    image: {{ .Values.image.registry }}/{{ .Values.image.repository }}:{{ .Values.image.tag }}

Inject Image Pull Secrets

Kubernetes requires a Secret of type kubernetes.io/dockerconfigjson to authenticate with a registry and pull a private image. When you reference a private image in a Pod definition, you also provide the name of the Secret in a imagePullSecrets key in the Pod definition. For more information, see Specifying imagePullSecrets on a Pod in the Kubernetes documentation.

During installation, KOTS creates a kubernetes.io/dockerconfigjson type Secret that is based on the customer license. This pull secret grants access to the private image through the Replicated proxy service or in the Replicated registry. Additionally, if the user configured a local image registry, then the pull secret contains the credentials for the local registry. You must provide the name of this KOTS-generated pull secret in any Pod definitions that reference the private image.

You can inject the name of this pull secret into a field in the HelmChart custom resource using the Replicated ImagePullSecretName template function. During installation, KOTS sets the value of the corresponding field in your Helm chart values.yaml file with the rendered value of the ImagePullSecretName template function.

Example

The following example shows a spec.values.image.pullSecrets array in the HelmChart custom resource that uses the ImagePullSecretName template function to inject the name of the KOTS-generated pull secret:

# kots.io/v1beta2 HelmChart custom resource

apiVersion: kots.io/v1beta2
kind: HelmChart
metadata:
  name: samplechart
spec:
  values:
    image:
      registry: '{{repl HasLocalRegistry | ternary LocalRegistryHost "proxy.replicated.com" }}'
      repository: '{{repl HasLocalRegistry | ternary LocalRegistryNamespace "proxy/my-app/ecr.us-east-1.amazonaws.com/my-org" }}/api'
      pullSecrets:
      - name: '{{repl ImagePullSecretName }}'

The spec.values.image.pullSecrets array in the HelmChart custom resource corresponds to a image.pullSecrets array in the Helm chart values.yaml file, as shown in the example below:

# Helm chart values.yaml file

image:
  registry: ecr.us-east-1.amazonaws.com
  repository: my-org/api/nginx
  pullSecrets:
  - name: my-org-secret

During installation, KOTS renders the ImagePullSecretName template function and adds the rendered pull secret name to the image.pullSecrets array in the Helm chart values.yaml file. Any templates in the Helm chart that access the image.pullSecrets field are updated to use the name of the KOTS-generated pull secret, as shown in the example below:

apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
  - name: nginx
    image: {{ .Values.image.registry }}/{{ .Values.image.repository }}
  {{- with .Values.image.pullSecrets }}
  imagePullSecrets:
  {{- toYaml . | nindent 2 }}
  {{- end }}

Add Backup Labels for Snapshots

The Replicated snapshots feature requires the following labels on all resources in your Helm chart that you want to be included in the backup:

kots.io/backup: velero
kots.io/app-slug: APP_SLUG, where APP_SLUG is the slug of your Replicated application.

For more information about snapshots, see Understanding Backup and Restore.

To support backup and restore with snapshots, add the kots.io/backup: velero and kots.io/app-slug: APP_SLUG labels to fields under the HelmChart custom resource optionalValues key. Add a when statement that evaluates to true only when the customer license has the isSnapshotSupported entitlement.

The fields that you create under the optionalValues key must map to fields in your Helm chart values.yaml file. For more information about working with the optionalValues key, see optionalValues in HelmChart v2.

Example

The following example shows how to add backup labels for snapshots in the optionalValues key of the HelmChart custom resource:

# kots.io/v1beta2 HelmChart custom resource

apiVersion: kots.io/v1beta2
kind: HelmChart
metadata:
  name: samplechart
spec:
  ...
  optionalValues:
  # add backup labels only if the license supports snapshots
  - when: "repl{{ LicenseFieldValue `isSnapshotSupported` }}"
    recursiveMerge: true
    values:
      mariadb:
        commonLabels:
          kots.io/backup: velero
          kots.io/app-slug: repl{{ LicenseFieldValue "appSlug" }}
        podLabels:
          kots.io/backup: velero
          kots.io/app-slug: repl{{ LicenseFieldValue "appSlug" }}

Support Local Image Registries for Online Installations

Local image registries are required for KOTS installations in air gapped environments. Also, users in online environments can optionally push images to a local private registry. For more information about how users configure a local image registry with KOTS, see Using Private Registries.

To support the use of local registries for online installations with version kots.io/v1beta2 of the HelmChart custom resource, you must provide the necessary values in the builder field to render the Helm chart with all of the necessary images so that KOTS knows where to pull the images from to push them into the private registry.

For more information about how to configure the builder key, see builder in HelmChart v2.

note

If you already configured the builder key previously to support air gap installations, then you can use the same configuration in your HelmChart custom resource to support the use of local registries for online installations. No additional configuration is required.

Configuring the HelmChart Custom Resource v2

Overview​

HelmChart v1 and v2 Differences​

Workflow​

Rewrite Image Names​

External Private Registries​

Local Registries​

Inject Image Pull Secrets​

Add Backup Labels for Snapshots​

Support Local Image Registries for Online Installations​

Overview

HelmChart v1 and v2 Differences

Workflow

Rewrite Image Names

External Private Registries

Local Registries

Inject Image Pull Secrets

Add Backup Labels for Snapshots

Support Local Image Registries for Online Installations