How to disable route pre-rendering in Next.js?

I have a route such as app/blog/rss.xml/route.ts:

import { getBlogPosts } from '@/routines/getBlogPosts.ts';
import Rss from 'rss';

const SITE_URL = 'https://ray.run';

export const GET = async () => {
  const blogPosts = await getBlogPosts();

  const feed = new Rss({
    description: 'Lessons learned scaling Playwright test automation',
    feed_url: `${SITE_URL}/blog/rss.xml`,
    language: 'en',
    site_url: SITE_URL,
    title: 'Rayrun Blog',
  });

  for (const blogPost of blogPosts) {
    if (!blogPost.publishedAt) {
      continue;
    }

    feed.item({
      author: blogPost.author.name,
      date: blogPost.publishedAt,
      description: blogPost.description,
      guid: `${SITE_URL}/blog/${blogPost.guid}`,
      title: blogPost.title,
      url: `${SITE_URL}/blog/${blogPost.slug}`,
    });
  }

  return new Response(feed.xml(), {
    headers: {
      'content-type': 'application/xml',
    },
  });
};

Next.js tries to pre-render this page when I run next build. How do I disable that?

I've already looked through documentation and there is no mention of this.

I should have mentioned that the problem is that it seems no matter what settings I set, Next.js attempts to pre-render the page, i.e. even if I add export const dynamic = "force-dynamic"; the build fails with error complaining about export const GET = async () => {} failing.

GET fails during the build because the build environment does not have access to the database, i.e. I need to entirely skip GET during build.

The only way I found around this is checking if the variable is unset and returning dummy content, e.g.

export const GET = async () => {
  if (!process.env.POSTGRES_DSN) {
    return new Response('OK');
  }
  // ...
};

The same is also true for sitemap.ts.

Update: Turns out that for routes what Fabio suggested is the correct course of action. However, I was thrown off by the fact that sitemap.ts does not behave that way – it ignores entirely the dynamic attribute. I ended up rewriting sitemap.ts to sitemap.xml/route.ts

Solution

As seen in the documentation here, route handlers are statically evaluated by default when using the GET method with the Response object.

import { NextResponse } from 'next/server';
 
export async function GET() {
  const res = await fetch("https://example.com/api/test");
  const data = await res.json();
  return NextResponse.json(data);
}

However if you want a dynamic route handler, one of the following requirements or configuration options need to be met:

Using the Request object with the GET method.
Using any of the other HTTP methods.
Using Dynamic Functions like cookies and headers.
The Segment Config Options manually specifies dynamic mode.

If none of the first three options suit your needs, you could use a segment configuration as seen in the example below:

import { NextResponse } from 'next/server';
 
export async function GET() {
  const res = await fetch("https://example.com/api/test");
  const data = await res.json();
  return NextResponse.json(data);
}

// forces the route handler to be dynamic
export const dynamic = "force-dynamic";

Please note that stack overflow expects you to do a certain degree on research yourself before posting a question, this answer is curated information from the official documentation, ultimately from the link you have provided yourself.