Getting started

The quickest way to try Cleat is the playground, which runs the real checker in your browser. To use it on your own files, build the cleat command.

Install

Cleat is built from source for now. rustup installs the Rust version the repository pins in rust-toolchain.toml.

git clone https://github.com/xorps/cleat-lang && cd cleat-lang
cargo install --path crates/cleat      # installs the `cleat` binary
schemas/fetch.sh 1.37                  # the Kubernetes OpenAPI spec, checksum-verified

Your first file

Save this as hello.cleat:

input name: Str
input replicas: Int where self >= 1 = 1

export {
  apiVersion: "v1",
  kind: "ConfigMap",
  metadata.name: "hello-\(name)",
  data.replicas: "\(replicas)",
}

Check it, then export it with inputs:

$ cleat check hello.cleat
0 error(s), 0 warning(s); refinements: 1 proved statically, 0 checked at runtime
$ cleat export hello.cleat --set name=world
apiVersion: v1
kind: ConfigMap
metadata:
  name: hello-world
data:
  replicas: "1"

--set decodes each value by the input’s declared type, so --set replicas=3 is an integer and --set replicas=0 is rejected by the where constraint. Inputs can also come from a JSON or YAML file: --input values.yaml.

Against the Kubernetes API

Import the schema, and resources are checked field by field:

import * as k8s from "./schemas/kubernetes-1.37.json"

export k8s.ConfigMap {
  metadata.name: "hello",
  data.greeting: "hi",
}

See Kubernetes and CRD types for CRDs and for narrowing types to your own policies.

Editor

For VS Code, build and install the extension (no npm needed):

editors/vscode/package.sh && code --install-extension editors/vscode/cleat.vsix

See Editors for what it does and for other editors.

Next

• A tour of the language
• The examples in the repository: the quickstart, a web app with its database, and a shared base with a production overlay.