env not required during build

next.config.js

@@ -1,4 +1,5 @@
 const envVar = require('env-var')
+const isBuildStage = envVar.get('IS_BUILD_STAGE').default('false').asBool()
 
 /** @type {import('next').NextConfig} */
 const nextConfig = {
@@ -6,13 +7,13 @@ const nextConfig = {
   swcMinify: true,
   /** @type {import('next/config').ServerRuntimeConfig} */
   serverRuntimeConfig: {
-    MONGO_URL: envVar.get('MONGO_URL').required().asUrlString(),
-    MONGO_DB: envVar.get('MONGO_DB').required().asString(),
-    MONGO_USER: envVar.get('MONGO_USER').required().asString(),
-    MONGO_PASS: envVar.get('MONGO_PASS').required().asString()
+    MONGO_URL: envVar.get('MONGO_URL').required(!isBuildStage).asUrlString(),
+    MONGO_DB: envVar.get('MONGO_DB').required(!isBuildStage).asString(),
+    MONGO_USER: envVar.get('MONGO_USER').required(!isBuildStage).asString(),
+    MONGO_PASS: envVar.get('MONGO_PASS').required(!isBuildStage).asString()
   },
   publicRuntimeConfig: {
-    TENANT_TYPE: envVar.get('TENANT_TYPE').asString()
+    TENANT_TYPE: envVar.get('TENANT_TYPE').required(!isBuildStage).asString()
   }
 }
 

src/database/start.ts

@@ -9,6 +9,7 @@ const {
 } = getConfig()
 
 async function getDatabase() {
+  if (!MONGO_URL || !MONGO_DB) return undefined
   const url = `mongodb://${MONGO_USER ? `${MONGO_USER}:${MONGO_PASS ?? ''}@` : ''}${MONGO_URL}`
   const client = new MongoClient(url)
   await client.connect()

src/next-types.d.ts

@@ -1,7 +1,7 @@
 declare module 'next/config' {
   export interface ServerRuntimeConfig {
-    MONGO_URL: string
-    MONGO_DB: string
+    MONGO_URL?: string
+    MONGO_DB?: string
     MONGO_USER?: string
     MONGO_PASS?: string
   }