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Kustomize

The following configuration options are available for Kustomize:

  • namePrefix is a prefix appended to resources for Kustomize apps
  • nameSuffix is a suffix appended to resources for Kustomize apps
  • images is a list of Kustomize image overrides
  • replicas is a list of Kustomize replica overrides
  • commonLabels is a string map of additional labels
  • labelWithoutSelector is a boolean value which defines if the common label(s) should be applied to resource selectors and templates.
  • forceCommonLabels is a boolean value which defines if it's allowed to override existing labels
  • commonAnnotations is a string map of additional annotations
  • namespace is a Kubernetes resources namespace
  • forceCommonAnnotations is a boolean value which defines if it's allowed to override existing annotations
  • commonAnnotationsEnvsubst is a boolean value which enables env variables substition in annotation values
  • patches is a list of Kustomize patches that supports inline updates
  • components is a list of Kustomize components

To use Kustomize with an overlay, point your path to the overlay.

Tip

If you're generating resources, you should read up how to ignore those generated resources using the IgnoreExtraneous compare option.

Patches

Patches are a way to kustomize resources using inline configurations in Argo CD applications. patches follow the same logic as the corresponding Kustomization. Any patches that target existing Kustomization file will be merged.

This Kustomize example sources manifests from the /kustomize-guestbook folder of the argoproj/argocd-example-apps repository, and patches the Deployment to use port 443 on the container. 

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
metadata:
  name: kustomize-inline-example
namespace: test1
resources:
  - https://github.com/argoproj/argocd-example-apps//kustomize-guestbook/
patches:
  - target:
      kind: Deployment
      name: guestbook-ui
    patch: |-
      - op: replace
        path: /spec/template/spec/containers/0/ports/0/containerPort
        value: 443

This Application does the equivalent using the inline kustomize.patches configuration. 

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: kustomize-inline-guestbook
  namespace: argocd
  finalizers:
    - resources-finalizer.argocd.argoproj.io
spec:
  destination:
    namespace: test1
    server: https://kubernetes.default.svc
  project: default
  source:
    path: kustomize-guestbook
    repoURL: https://github.com/argoproj/argocd-example-apps.git
    targetRevision: master
    kustomize:
      patches:
        - target:
            kind: Deployment
            name: guestbook-ui
          patch: |-
            - op: replace
              path: /spec/template/spec/containers/0/ports/0/containerPort
              value: 443

The inline kustomize patches work well with ApplicationSets, too. Instead of maintaining a patch or overlay for each cluster, patches can now be done in the Application template and utilize attributes from the generators. For example, with external-dns to set the txt-owner-id to the cluster name.

apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: external-dns
spec:
  goTemplate: true
  goTemplateOptions: ["missingkey=error"]
  generators:
  - clusters: {}
  template:
    metadata:
      name: 'external-dns'
    spec:
      project: default
      source:
        repoURL: https://github.com/kubernetes-sigs/external-dns/
        targetRevision: v0.14.0
        path: kustomize
        kustomize:
          patches:
          - target:
              kind: Deployment
              name: external-dns
            patch: |-
              - op: add
                path: /spec/template/spec/containers/0/args/3
                value: --txt-owner-id={{.name}}   # patch using attribute from generator
      destination:
        name: 'in-cluster'
        namespace: default

Components

Kustomize components encapsulate both resources and patches together. They provide a powerful way to modularize and reuse configuration in Kubernetes applications.

Outside of Argo CD, to utilize components, you must add the following to the kustomization.yaml that the Application references. For example: 

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
...
components:
- ../component

With support added for components in v2.10.0, you can now reference a component directly in the Application: 

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: application-kustomize-components
spec:
  ...
  source:
    path: examples/application-kustomize-components/base
    repoURL: https://github.com/my-user/my-repo
    targetRevision: main

    # This!
    kustomize:
      components:
        - ../component  # relative to the kustomization.yaml (`source.path`).

Private Remote Bases

If you have remote bases that are either (a) HTTPS and need username/password (b) SSH and need SSH private key, then they'll inherit that from the app's repo.

This will work if the remote bases uses the same credentials/private key. It will not work if they use different ones. For security reasons your app only ever knows about its own repo (not other team's or users repos), and so you won't be able to access other private repos, even if Argo CD knows about them.

Read more about private repos.

kustomize build Options/Parameters

To provide build options to kustomize build of default Kustomize version, use kustomize.buildOptions field of argocd-cm ConfigMap. Use kustomize.buildOptions.<version> to register version specific build options.

apiVersion: v1
kind: ConfigMap
metadata:
  name: argocd-cm
  namespace: argocd
  labels:
    app.kubernetes.io/name: argocd-cm
    app.kubernetes.io/part-of: argocd
data:
    kustomize.buildOptions: --load-restrictor LoadRestrictionsNone
    kustomize.buildOptions.v4.4.0: --output /tmp

After modifying kustomize.buildOptions, you may need to restart ArgoCD for the changes to take effect.

Custom Kustomize versions

Argo CD supports using multiple Kustomize versions simultaneously and specifies required version per application. To add additional versions make sure required versions are bundled and then use kustomize.path.<version> fields of argocd-cm ConfigMap to register bundled additional versions.

apiVersion: v1
kind: ConfigMap
metadata:
  name: argocd-cm
  namespace: argocd
  labels:
    app.kubernetes.io/name: argocd-cm
    app.kubernetes.io/part-of: argocd
data:
    kustomize.path.v3.5.1: /custom-tools/kustomize_3_5_1
    kustomize.path.v3.5.4: /custom-tools/kustomize_3_5_4

Once a new version is configured you can reference it in an Application spec as follows:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: guestbook
spec:
  source:
    repoURL: https://github.com/argoproj/argocd-example-apps.git
    targetRevision: HEAD
    path: kustomize-guestbook

    kustomize:
      version: v3.5.4

Additionally, the application kustomize version can be configured using the Parameters tab of the Application Details page, or using the following CLI command:

argocd app set <appName> --kustomize-version v3.5.4

Build Environment

Kustomize apps have access to the standard build environment which can be used in combination with a config managment plugin to alter the rendered manifests.

You can use these build environment variables in your Argo CD Application manifests. You can enable this by setting .spec.source.kustomize.commonAnnotationsEnvsubst to true in your Application manifest.

For example, the following Application manifest will set the app-source annotation to the name of the Application:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: guestbook-app
  namespace: argocd
spec:
  project: default
  destination:
    namespace: demo
    server: https://kubernetes.default.svc
  source:
    path: kustomize-guestbook
    repoURL: https://github.com/argoproj/argocd-example-apps
    targetRevision: HEAD
    kustomize:
      commonAnnotationsEnvsubst: true
      commonAnnotations:
        app-source: ${ARGOCD_APP_NAME}
  syncPolicy:
    syncOptions:
      - CreateNamespace=true

Kustomizing Helm charts

It's possible to render Helm charts with Kustomize. Doing so requires that you pass the --enable-helm flag to the kustomize build command. This flag is not part of the Kustomize options within Argo CD. If you would like to render Helm charts through Kustomize in an Argo CD application, you have two options: You can either create a custom plugin, or modify the argocd-cm ConfigMap to include the --enable-helm flag globally for all Kustomize applications:

apiVersion: v1
kind: ConfigMap
metadata:
  name: argocd-cm
  namespace: argocd
data:
  kustomize.buildOptions: --enable-helm

Setting the manifests' namespace

The spec.destination.namespace field only adds a namespace when it's missing from the manifests generated by Kustomize. It also uses kubectl to set the namespace, which sometimes misses namespace fields in certain resources (for example, custom resources). In these cases, you might get an error like this: ClusterRoleBinding.rbac.authorization.k8s.io "example" is invalid: subjects[0].namespace: Required value.

Using Kustomize directly to set the missing namespaces can resolve this problem. Setting spec.source.kustomize.namespace instructs Kustomize to set namespace fields to the given value.

If spec.destination.namespace and spec.source.kustomize.namespace are both set, Argo CD will defer to the latter, the namespace value set by Kustomize.