Argo CD with Helm and Kustomize: CAPA practice questions

Argo CD supports several ways of producing manifests, and it detects the tool for a source path by itself unless the Application sets one explicitly. A Chart.yaml file means Helm, a kustomization.yaml, kustomization.yml or Kustomization file means Kustomize, and anything else is treated as a plain directory of YAML or JSON manifests. Config management plugins cover other tools.

Helm is used only to inflate charts with helm template. Argo CD then applies the rendered manifests and manages their lifecycle itself, so helm ls does not show the release. The release name defaults to the Application name and can be changed with releaseName, although that can upset charts whose selectors use the app.kubernetes.io/instance label. Values come from several places with a fixed precedence: parameters beat valuesObject, which beats values, which beats valueFiles, which beat the chart's own values.yaml. Among several valueFiles, the later file wins, and ignoreMissingValueFiles skips files that do not exist. Helm hooks are mapped onto Argo CD hooks: pre-install and pre-upgrade become PreSync, post-install and post-upgrade become PostSync, and the rollback hooks are not supported. Charts come from Helm repositories, OCI registries or Git paths, and a values file kept in a different repository uses a multi-source Application with a ref.

Kustomize applications are rendered with kustomize build. The kustomize block of an Application can override or extend the kustomization without editing it: namePrefix and nameSuffix, images to swap image tags, replicas, commonLabels and commonAnnotations, a namespace, components, and inline patches that are merged with those in the kustomization file. Inline patches are handy with ApplicationSets, where one template can patch each generated application with values from its generator. Build options for every Kustomize application are set in argocd-cm with kustomize.buildOptions, and a version-specific entry registers options for a named Kustomize version.

The two tools can also be combined. Kustomize can render a Helm chart through its helmCharts field, but only when kustomize build receives --enable-helm, so Argo CD needs that flag in kustomize.buildOptions or a config management plugin. Because Argo CD renders everything in the repository server, the chart and kustomization must be reachable from there, with repository credentials registered in Argo CD.