L9T

Reusable typesafe kubernetes configurations with fast development cycle and hot reloading, and zero yaml.

Why?

Because working with kubernetes configs and helm is painful:

YAML/JSON without proper valdiation is error prone.
Go templates are ugly and too limited.
Subcharts are pain to manage.

How?

TypeScript + Deno + kubectl.

Usage

To use l9t you need to install deno.

Then you can create a configuration:

import l9t, {
  Deployment,
  Service,
} from "https://deno.land/x/l9t/l9t.ts";

// types for variables aren't required but useful for ides
const deployment = (
  { build }: { build: string },
): Deployment => ({
  apiVersion: "apps/v1",
  kind: "Deployment",
  metadata: {
    name: "hello-world",
  },
  spec: {
    selector: {
      matchLabels: {
        app: "hello-world",
      },
    },
    replicas: build === "prod" ? 10 : 2,
    template: {
      metadata: {
        labels: {
          app: "hello-world",
        },
      },
      spec: {
        containers: [
          {
            name: "hello-world",
            image: "nginx:latest",
            ports: [
              {
                containerPort: 80,
              },
            ],
          },
        ],
      },
    },
  },
});

const service = ({}): Service => ({
  apiVersion: "v1",
  kind: "Service",
  metadata: {
    name: "hello-world",
  },
  spec: {
    selector: {
      app: "hello-world",
    },
    ports: [
      {
        protocol: "TCP",
        port: 80,
        targetPort: 80,
      },
    ],
    type: "LoadBalancer",
  },
});

const params = {
  build: Deno.env.get("BUILD") || "dev",
};

l9t([deployment(params), service(params)], import.meta);

Apply the configuration with:

deno run -A hello_world.ts apply

And check that it works with:

curl localhost:80

For interactive development you can use watch mode:

deno run hello_world.ts -A watch

As the configuration has Deno.env.get("BUILD") === "prod" ? 10 : 2, it's possible to make a prod configurationwith more replicas with:

BUILD=prod deno run -A hello_world.ts apply

If you just want to compile TypeScript configuration to YAML run:

deno run -A hello_world.ts compile

Examples:

Goals

❓ Types for Kubernetes APIs.

✅ Hot reloading.

❓ Helm charts-like reusable configuration packages.

Development

Prerequisites

kubectl
deno

Generate types

To generate new version of the default types run:

kubectl proxy --port=8080
curl -k localhost:8080/openapi/v2 > spec.json
deno run --unstable --allow-read src/scripts/make_types.ts io.k8s KubernetesResources > src/types/k8s.ts
deno fmt

It's possible to generate types for your kuernetes extensions, like:

deno run --unstable --allow-read src/scripts/make_types.ts EXTENSION_NS MyExtensionResources > ext.ts

And use it like:

import l9t, { KubernetesResources } from "https://deno.land/x/l9t/l9t.ts";
import { MyExtensionResources } from "./ext.ts";

...

l9t<KubernetesResources | MyExtensionResources>([...], import.meta);

Testing

To run test execute:

deno test

nvbn / l9t

L9T