Add nextauth internal url (#153)

* Add nextauth_internal_url

* Add NEXTAUTH_URL_INTERNAL option

---------

Co-authored-by: KM Koushik <koushikmohan1996@gmail.com>

Author: batizisanya

.env.example

@@ -23,6 +23,10 @@ DATABASE_URL="postgresql://splitpro:password@localhost:54321/splitpro"
 NEXTAUTH_SECRET="secret"
 NEXTAUTH_URL="http://localhost:3000"
 
+# If provided, server-side calls will use this instead of NEXTAUTH_URL. Useful in environments when the server doesn't have access to the canonical URL of your site.
+# NEXTAUTH_URL_INTERNAL="http://localhost:3000"
+
+
 # Enable sending invites
 ENABLE_SENDING_INVITES=false
 #********* END OF REQUIRED ENV VARS *********

src/env.js

@@ -23,6 +23,10 @@ export const env = createEnv({
       // VERCEL_URL doesn't include `https` so it cant be validated as a URL
       process.env.VERCEL ? z.string() : z.string().url(),
     ),
+    NEXTAUTH_URL_INTERNAL: z.preprocess(
+      (str) => process.env.VERCEL_URL ?? str,
+      process.env.VERCEL ? z.string() : z.string().url(),
+    ),
     ENABLE_SENDING_INVITES: z.boolean(),
     FROM_EMAIL: z.string().optional(),
     EMAIL_SERVER_HOST: z.string().optional(),
@@ -64,6 +68,7 @@ export const env = createEnv({
     NODE_ENV: process.env.NODE_ENV,
     NEXTAUTH_SECRET: process.env.NEXTAUTH_SECRET,
     NEXTAUTH_URL: process.env.NEXTAUTH_URL,
+    NEXTAUTH_URL_INTERNAL: process.env.NEXTAUTH_URL_INTERNAL ?? process.env.NEXTAUTH_URL,
     ENABLE_SENDING_INVITES: process.env.ENABLE_SENDING_INVITES === 'true',
     FROM_EMAIL: process.env.FROM_EMAIL,
     EMAIL_SERVER_HOST: process.env.EMAIL_SERVER_HOST,