Virtual hosting guide

  // There is a database connection in `ctx.data`.

});

~~~~

Another example is to determine the virtual host of the server based on the

incoming HTTP request.  See the [next section](#virtual-hosting) for details.

Virtual hosting

---------------

You may want to support multiple domains on the same server, so-called

*virtual hosts*.  To determine the virtual host of the server based on the

incoming HTTP request, you can set the `TContextData` type to a type that

contains the virtual host information:

~~~~ typescript

import { createFederation } from "@fedify/fedify";

export interface VirtualHost {

  host: string;

}

export function parseVirtualHost(url: URL | string): VirtualHost {

  url = typeof url === "string" ? new URL(url) : url;

  return { host: url.hostname };

}

const federation = createFederation<VirtualHost>({

  // Omitted for brevity; see the related section for details.

});

~~~~

Then, you can pass the virtual host information to the `Federation.fetch()`

as the `contextData` option:

::: code-group

~~~~ typescript [Deno]

Deno.serve(

  request => federation.fetch(request, {

    contextData: parseVirtualHost(request.url), // [!code highlight]

  })

);

~~~~

~~~~ typescript [Node.js]

import { serve } from "@hono/node-server";

serve({

  fetch(request) {

    return federation.fetch(request, {

      contextData: parseVirtualHost(request.url), // [!code highlight]

    });

  }

})

~~~~

~~~~ typescript [Bun]

Bun.serve({

  fetch(request) {

    return federation.fetch(request, {

      contextData: parseVirtualHost(request.url), // [!code highlight]

    });

  }

});

~~~~

:::

Now you can access the virtual host information in the actor dispatcher,

inbox listener, and other callback functions:

~~~~ typescript{2-3}

federation.setActorDispatcher("/@{handle}", (ctx, handle) => {

  const { host } = ctx.data;

  const fullHandle = `${handle}@${host}`;

  // Omitted for brevity

});

~~~~