Argo CD

Cleat runs as an Argo CD config management plugin: a sidecar container next to argocd-repo-server. The sidecar image is about 6 MB: a statically linked cleat and the plugin config on distroless, with no shell.

Install the sidecar

Build and push the image (multi-architecture builds need no emulation):

docker buildx build -f deploy/argocd/Dockerfile --platform linux/amd64,linux/arm64 \
  -t registry.example.com/cleat-cmp:dev --push .

Then add the sidecar to the repo server. Edit the image in deploy/argocd/repo-server-patch.yaml to the one you pushed, and apply it:

kubectl -n argocd patch deployment argocd-repo-server --patch-file deploy/argocd/repo-server-patch.yaml

The image carries its plugin config (deploy/argocd/plugin.yaml), so nothing else needs to be installed. The plugin is called cleat-v1, and it also matches, without being named, any application whose directory has a main.cleat.

An Application

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata: { name: shop, namespace: argocd }
spec:
  project: default
  source:
    repoURL: https://github.com/acme/deploy.git
    targetRevision: main
    path: apps/shop
    plugin:
      name: cleat-v1
      parameters:
        - { name: env, string: prod }
        - { name: image, string: ghcr.io/acme/api:1.4.2 }
  destination: { server: https://kubernetes.default.svc, namespace: shop }

What you get

• Parameters in the UI. Each input in the entry file is announced to Argo CD as a parameter, with its type as the tooltip and its default filled in.
• Typed parameters. String parameters are decoded by the input’s type, as with --set; array and map parameters become lists and maps.
• Errors in the Application’s status. An invalid parameter or a type error fails the manifest generation with Cleat’s message, for example input `env`: expected `Env` (`"dev" | "prod"`), got "production" (string).
• Sync waves from after dependencies (see Components).
• Imports stay in the repository. The project root is the repository checkout, so an application can import shared modules and schemas from elsewhere in the repository, and nothing outside it.

Testing it

deploy/argocd/e2e/run.sh creates a throwaway kind cluster, installs a pinned Argo CD, builds the sidecar, and checks all of the above against a real Argo CD. deploy/argocd/e2e/run.sh cleanup deletes the cluster. In the repository’s CI it runs weekly, on demand, and on pull requests labeled e2e.