How to write a rewrite rule to remove the query parameters - Next.js app with proxy to another Next.js app

[ThangHuuVu]

Hi there 👋, I want to ask about this case for Netlify Proxies:

1. I have my main app deployed at authjs-with-proxy.netlify.app/
2. I have my Auth app deployed at https://next-auth-behind-cdn.vercel.app/authjs/ (with custom basePath and trailing slash)
3. I proxy my /authjs in the main app to the Auth app in the _redirects file: /authjs/* https://next-auth-behind-cdn.vercel.app/authjs/:splat 200!
4. I log in at authjs-with-proxy.netlify.app/authjs
5. I got navigated back to authjs-with-proxy.netlify.app/authjs . On the address bar, the query params code and state are still shown, while I expect it to not shown
   

This is not happening in a normal Auth app, where the query parameters got stripped down after the OAuth callback.

I'm currently removing the query params by using the Next.js router like this:

  const router = useRouter();
  if (router.query.code && router.query.state) router.replace('/', undefined, { shallow: true });

but I feel this can be achieved using either Netlify rewrites or Next.js rewrites. I've tried:
_redirects file

/authjs/?code=:code&state=:state /authjs/ 200
/authjs/?state=:state&code=:code /authjs/ 200

or in my Auth app's next.config.js:

const isProd = process.env.NODE_ENV === 'production'

module.exports = {
  trailingSlash: true,
  assetPrefix: isProd ? process.env.NEXT_PUBLIC_ASSET_PREFIX : undefined,
  basePath: process.env.NEXT_PUBLIC_ASSET_PREFIX,
  async rewrites() {
    return [
      {
        source: '/',
        has: [
          {
            type: 'query',
            key: 'state',
          },
          {
            type: 'query',
            key: 'code',
          },
        ],
        destination: '/',
      },
    ];
  },
}

None of the above works for me, so I would really appreciate any help here 🙏 Thanks for reading!
Repos:

• https://github.com/nextauthjs/next-auth-behind-cdn
• https://github.com/nextauthjs/auth-with-proxy

[MarcL]

Hey @ThangHuuVu.

I've spoken to the team working on our redirect engine and you can add a ? to the redirect target to suppress the query parameters.

[ThangHuuVu]

Hi, @MarcL thanks for answering me
https://github.com/nextauthjs/auth-with-proxy/blob/main/public/_redirects I updated the ? to the redirect targets but it doesn't seem to work 🤔 And the warning is still shown in the Netlify console.

https://app.netlify.com/sites/authjs-with-proxy/deploys/640685e5bbf7590008e70005

7:32:23 AM: Next.js cache saved.
7:32:23 AM: You have the following Netlify rewrites that might cause conflicts with the Next.js Runtime:
7:32:23 AM: 
7:32:23 AM: - /authjs/?code=:code&state=:state /authjs/? 200
7:32:23 AM: - /authjs/?state=:state&code=:code /authjs/? 200
7:32:23 AM: 
7:32:23 AM: For more information, see https://ntl.fyi/next-rewrites