prevent next.config defaults from being constantly assigned

vercel · Sep 1, 2023 · ca33652 · ca33652
1 parent 97e85bb
commit ca33652
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Showing 2 changed files with 15 additions and 9 deletions.
diff --git a/packages/next/src/bin/next.ts b/packages/next/src/bin/next.ts
@@ -135,15 +135,6 @@ async function main() {
     )
     const origEnv = Object.assign({}, process.env)
 
-    // TODO: set config to env variable to be re-used so we don't reload
-    // un-necessarily
-    const config = await loadConfig(
-      command === 'dev' ? PHASE_DEVELOPMENT_SERVER : PHASE_PRODUCTION_SERVER,
-      dir,
-      undefined,
-      undefined,
-      true
-    )
     let dirsResult: ReturnType<typeof findPagesDir> | undefined = undefined
 
     try {
@@ -156,6 +147,18 @@ async function main() {
       process.env = origEnv
     }
 
+    // TODO: set config to env variable to be re-used so we don't reload
+    // un-necessarily
+    const config = await loadConfig(
+      command === 'dev' ? PHASE_DEVELOPMENT_SERVER : PHASE_PRODUCTION_SERVER,
+      dir,
+      undefined,
+      undefined,
+      true
+    )
+
+    process.env.__NEXT_PRIVATE_CONFIG_INITIALIZED = '1'
+
     if (dirsResult?.appDir) {
       // we need to reset env if we are going to create
       // the worker process with the esm loader so that the

diff --git a/packages/next/src/server/config.ts b/packages/next/src/server/config.ts
@@ -186,6 +186,9 @@ function assignDefaults(
 
   const result = { ...defaultConfig, ...config }
 
+  // avoid mutating config if it was already initialized
+  if (process.env.__NEXT_PRIVATE_CONFIG_INITIALIZED) return result
+
   if (result.output === 'export') {
     if (result.i18n) {
       throw new Error(