Programmatic Configuration

For configuration that goes beyond YAML — computed values, environment-dependent logic, or TypeScript type safety — use dune.config.ts.

Basic usage

// dune.config.ts
import type { DuneConfig } from "dune";

export default {
  site: {
    title: "My Site",
    url: Deno.env.get("SITE_URL") ?? "http://localhost:8000",
  },
  system: {
    debug: Deno.env.get("DUNE_ENV") !== "production",
  },
} satisfies Partial<DuneConfig>;

Async configuration

Export a function for async configuration (e.g., fetching secrets):

// dune.config.ts
export default async function () {
  const apiKey = Deno.env.get("API_KEY");

  return {
    site: {
      metadata: {
        "analytics-id": apiKey ?? "",
      },
    },
  };
}

When to use dune.config.ts

Scenario	Use YAML	Use dune.config.ts
Static values	✓
Environment variables	✓ (via env/ overrides)	✓ (more flexible)
Computed values		✓
Conditional logic		✓
Type safety		✓
External secrets		✓
Non-developers manage it	✓

Most sites only need YAML. Use dune.config.ts when you outgrow it.

Merge behavior

dune.config.ts is layer 4 in the merge hierarchy. It overrides YAML config but is itself overridden by page frontmatter. The merge is deep — you only need to specify the fields you want to change.