How do I put a nextjs app in maintenance mode (using Vercel)

Question

I've just released my nextjs app to production using Vercel.

I'm loving the whole experience except for one tiny part: I would have loved to be able to put my app in maintenance mode, but this option does not seem available on Vercel.

My question is: Has anyone achieved this before and could share some details here?

I'm guessing it could be done at 2 levels:

• Modifying my app so that if an environment variable (i.e MAINTENANCE_MODE=true) is detected, every page redirects to a maintenance screen. However, this is not ideal, because adding an environment variable on Vercel requires a deployment for it to be taken into account.
• Having a simple per-project toggle to enable/disable maintenance mode from Vercel. That would be mind-blowing.

Answer 1

"Maintenance Mode" can be achieved with an Environment Variable and redirects property in your next.config.js (requires Next.js 9.5.0 or newer).

module.exports = {
  redirects() {
    return [
      process.env.MAINTENANCE_MODE === "1"
        ? { source: "/((?!maintenance).*)", destination: "/maintenance.html", permanent: false }
        : null,
    ].filter(Boolean);
  }
};

This adds a wildcard route that matches incoming requests and then issues a temporary redirect the /maintenance.html location.

Note that you cannot make changes to a deployment (config or environment variables) without deploying again.

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Old Answer

If you're not using Next.js or using an old version of Next.js, "Maintenance Mode" can be achieved with the redirects property in vercel.json.

{
  "redirects": [
    { "source": "/((?!maintenance).*)", "destination": "/maintenance.html", "permanent": false }
  ]
}