feat: set NEXTAUTH_URL based on DEPLOY_PRIME_URL on Netlify

next.config.js

@@ -13,8 +13,21 @@ const jiti = createJiti(new URL(import.meta.url).pathname)
 jiti("./env/server")
 jiti("./env/client")
 
+// We set NEXTAUTH_URL here because next.config.js is included in Netlify
+// functions when bundling. Otherwise we are unable to login on preview
+// deployments. We use DEPLOY_PRIME_URL from Netlify for all non-production
+// branches. Locally we set it in .env.local instead of NEXTAUTH_URL.
+// Netlify`s Next.js Runtime has built-in support for Next-Auth,
+// but Next-Auth v5 is ESM and therefore not yet handle correctly by Netlify.
+// This workaround should not be needed once Netlify fixes their code.
 /** @type {import('next').NextConfig} */
 const nextConfig = {
+  env: {
+    NEXTAUTH_URL:
+      (process.env.CONTEXT === "production"
+        ? process.env.URL
+        : process.env.DEPLOY_PRIME_URL) + "/api/web/auth",
+  },
   poweredByHeader: false,
   eslint: { ignoreDuringBuilds: true },
   images: {