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How does ArgoCD work with Kustomize overlays for multiple environments?

Infrastructure as Code (Terraform, Ansible) · Advanced level

Answer

Argo CD can point an Application at a Git path containing a Kustomize overlay. For multiple environments, each Argo CD Application references a different overlay path or branch, and Argo CD renders Kustomize, compares desired state with the cluster, and syncs changes.

Technical explanation

Each environment overlay can map to a separate Argo CD Application or ApplicationSet entry.

Argo CD compares rendered manifests with live cluster state and reports drift.

Promotion can be implemented by changing Git paths, branches, or image tags.

Keep source manifests or IaC definitions readable enough that reviewers can understand the final desired state.

Use overlays, modules, or roles for reuse, but keep environment-specific differences explicit and reviewable.

Validate generated output in CI before applying it through kubectl, Argo CD, Terraform, or Ansible.

Hands-on example

1. Create a Kustomize base and overlay for: How does ArgoCD work with Kustomize overlays for multiple environments?

2. Base files:

base/deployment.yaml

base/service.yaml

base/kustomization.yaml

base/kustomization.yaml:

resources:

- deployment.yaml

- service.yaml

commonLabels:

app.kubernetes.io/name: payments

3. prod overlay:

resources:

- ../../base

namePrefix: prod-

namespace: payments-prod

images:

- name: ghcr.io/company/payments

newTag: 1.8.4

configMapGenerator:

- name: app-config

literals:

- LOG_LEVEL=info

patches:

- path: replica-patch.yaml

4. Render and apply:

kubectl kustomize overlays/prod

kubectl diff -k overlays/prod

kubectl apply -k overlays/prod

5. In GitOps, point Argo CD at overlays/prod and let it render, compare, and sync the desired state.

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