ArgoCD

kdef ships as an ArgoCD Config Management Plugin (CMP). Drop the sidecar into your argocd-repo-server, point an Application at a .kdef directory, and ArgoCD renders and deploys it.

1. Build the sidecar image

# From the kdef root
git clone https://github.com/gsid-nl/kdef.git
cd kdef

make build
cp kdef argocd-plugin/
cd argocd-plugin
docker build -t your-registry/kdef-argocd-plugin:latest .
docker push your-registry/kdef-argocd-plugin:latest

2. Add the sidecar to argocd-repo-server

In your ArgoCD Helm values (or patch the repo-server Deployment directly):

repoServer:
  extraContainers:
    - name: kdef
      image: your-registry/kdef-argocd-plugin:latest
      command: ["/var/run/argocd/argocd-cmp-server"]
      securityContext:
        runAsNonRoot: true
        runAsUser: 999
      volumeMounts:
        - { mountPath: /var/run/argocd,                 name: var-files }
        - { mountPath: /home/argocd/cmp-server/plugins, name: plugins }
        - { mountPath: /tmp,                            name: cmp-tmp }
  volumes:
    - name: cmp-tmp
      emptyDir: {}

The plugin manifest (plugin.yaml) inside the sidecar image tells ArgoCD how to detect kdef projects (presence of *.kdef files) and run kdef render.

3. Point an Application at it

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: my-app
  namespace: argocd
spec:
  project: default
  source:
    repoURL: https://github.com/example/my-app-k8s.git
    path: k8s/
    plugin:
      name: kdef
  destination:
    server: https://kubernetes.default.svc
    namespace: production
  syncPolicy:
    automated:
      prune: true
      selfHeal: true

ArgoCD auto-detects .kdef files in path and invokes the plugin to produce manifests.

Environment overrides

Pass an env through plugin parameters:

source:
  plugin:
    name: kdef
    env:
      - name: KDEF_ENV
        value: production

And update plugin.yaml inside the sidecar image to honor it:

generate:
  command: ["sh", "-c", "kdef render --dir . --env ${KDEF_ENV:-staging}"]

Tips

• Cluster generators — ApplicationSet + the list generator is the cleanest way to deploy the same kdef project to multiple environments. Point each generated Application at a different KDEF_ENV.
• Variable overrides — extend the generate command with --set for simple scalars, or use a values/*.json file committed alongside your kdef project.
• Validation — kdef exits non-zero on validation failures, so ArgoCD’s sync will fail fast instead of applying broken manifests.

When Flux and when ArgoCD?

Both work. If you already run one, use that one. If you’re choosing:

• Flux + kdef’s KdefRelease CR is the lighter-weight option — fewer moving parts, CRD-first UX.
• ArgoCD + CMP sidecar gives you ArgoCD’s UI and its multi-cluster / multi-project story out of the box.