ref(nextjs): Make build-phase check more robust

packages/nextjs/src/index.server.ts

@@ -22,7 +22,14 @@ export { ErrorBoundary, showReportDialog, withErrorBoundary } from '@sentry/reac
 type GlobalWithDistDir = typeof global & { __rewriteFramesDistDir__: string };
 const domain = domainModule as typeof domainModule & { active: (domainModule.Domain & Carrier) | null };
 
-const isVercel = !!process.env.VERCEL;
+// Exporting this constant means we can compute it without the linter complaining, even if we stop directly using it in
+// this file. It's important that it be computed as early as possible, because one of its indicators is seeing 'build'
+// (as in the CLI command `next build`) in `process.argv`. Later on in the build process, everything's been spun out
+// into child threads and `argv` turns into ['node', 'path/to/childProcess.js'], so the original indicator is lost. We
+// thus want to compute it as soon as the SDK is loaded for the first time, which is normally when the user imports
+// `withSentryConfig` into `next.config.js`.
+export const IS_BUILD = isBuild();
+const IS_VERCEL = !!process.env.VERCEL;
 
 /** Inits the Sentry NextJS SDK on node. */
 export function init(options: NextjsOptions): void {
@@ -63,7 +70,7 @@ export function init(options: NextjsOptions): void {
 
   configureScope(scope => {
     scope.setTag('runtime', 'node');
-    if (isVercel) {
+    if (IS_VERCEL) {
       scope.setTag('vercel', true);
     }
 
@@ -124,9 +131,16 @@ function addServerIntegrations(options: NextjsOptions): void {
   options.integrations = integrations;
 }
 
+// TODO (v8): Remove this
+/**
+ * @deprecated Use the constant `IS_BUILD` instead.
+ */
+const deprecatedIsBuild = (): boolean => isBuild();
+// eslint-disable-next-line deprecation/deprecation
+export { deprecatedIsBuild as isBuild };
+
 export type { SentryWebpackPluginOptions } from './config/types';
 export { withSentryConfig } from './config';
-export { isBuild } from './utils/isBuild';
 export {
   withSentryGetServerSideProps,
   withSentryGetStaticProps,
@@ -142,7 +156,7 @@ export {
 // deployments, because the current method of doing the wrapping a) crashes Next 12 apps deployed to Vercel and
 // b) doesn't work on those apps anyway. We also don't do it during build, because there's no server running in that
 // phase.)
-if (!isBuild() && !isVercel) {
+if (!IS_BUILD && !IS_VERCEL) {
   // Dynamically require the file because even importing from it causes Next 12 to crash on Vercel.
   // In environments where the JS file doesn't exist, such as testing, import the TS file.
   try {

packages/nextjs/src/utils/isBuild.ts

@@ -2,18 +2,24 @@
  * Decide if the currently running process is part of the build phase or happening at runtime.
  */
 export function isBuild(): boolean {
-  // During build, the main process is invoked by
-  //   `node next build`
-  // and child processes are invoked as
-  //   `node <path>/node_modules/.../jest-worker/processChild.js`.
-  // The former is (obviously) easy to recognize, but the latter could happen at runtime as well. Fortunately, the main
-  // process hits this file before any of the child processes do, so we're able to set an env variable which the child
-  // processes can then check. During runtime, the main process is invoked as
-  //   `node next start`
-  // or
-  //   `node /var/runtime/index.js`,
-  // so we never drop into the `if` in the first place.
-  if (process.argv.includes('build') || process.env.SENTRY_BUILD_PHASE) {
+  if (
+    // During build, the main process is invoked by
+    //   `node next build`
+    // and child processes are invoked as
+    //   `node <path>/node_modules/.../jest-worker/processChild.js`.
+    // The former is (obviously) easy to recognize, but the latter could happen at runtime as well. Fortunately, the main
+    // process hits this file before any of the child processes do, so we're able to set an env variable which the child
+    // processes can then check. During runtime, the main process is invoked as
+    //   `node next start`
+    // or
+    //   `node /var/runtime/index.js`,
+    // so we never drop into the `if` in the first place.
+    process.argv.includes('build') ||
+    process.env.SENTRY_BUILD_PHASE ||
+    // This is set by next, but not until partway through the build process, which is why we need the above checks. That
+    // said, in case this function isn't called until we're in a child process, it can serve as a good backup.
+    process.env.NEXT_PHASE === 'phase-production-build'
+  ) {
     process.env.SENTRY_BUILD_PHASE = 'true';
     return true;
   }