do Next.js version verification earlier and make it easy to grab the …

…version after build command finished

src/build/content/server.ts

@@ -20,7 +20,6 @@ import { prerelease, lt as semverLowerThan, lte as semverLowerThanOrEqual } from
 
 import { RUN_CONFIG } from '../../run/constants.js'
 import { PluginContext } from '../plugin-context.js'
-import { verifyNextVersion } from '../verification.js'
 
 const tracer = wrapTracer(trace.getTracer('Next runtime'))
 
@@ -292,26 +291,13 @@ export const copyNextDependencies = async (ctx: PluginContext): Promise<void> =>
 
     await Promise.all(promises)
 
-    // detect if it might lead to a runtime issue and throw an error upfront on build time instead of silently failing during runtime
     const serverHandlerRequire = createRequire(posixJoin(ctx.serverHandlerDir, ':internal:'))
 
-    let nextVersion: string | undefined
-    try {
-      const { version } = serverHandlerRequire('next/package.json')
-      if (version) {
-        nextVersion = version as string
-      }
-    } catch {
-      // failed to resolve package.json - currently this is resolvable in all known next versions, but if next implements
-      // exports map it still might be a problem in the future, so we are not breaking here
-    }
-
-    if (nextVersion) {
-      verifyNextVersion(ctx, nextVersion)
-
-      await patchNextModules(ctx, nextVersion, serverHandlerRequire.resolve)
+    if (ctx.nextVersion) {
+      await patchNextModules(ctx, ctx.nextVersion, serverHandlerRequire.resolve)
     }
 
+    // detect if it might lead to a runtime issue and throw an error upfront on build time instead of silently failing during runtime
     try {
       const nextEntryAbsolutePath = serverHandlerRequire.resolve('next')
       const nextRequire = createRequire(nextEntryAbsolutePath)

src/build/plugin-context.ts

@@ -1,6 +1,8 @@
 import { existsSync, readFileSync } from 'node:fs'
 import { readFile } from 'node:fs/promises'
+import { createRequire } from 'node:module'
 import { join, relative, resolve } from 'node:path'
+import { join as posixJoin } from 'node:path/posix'
 import { fileURLToPath } from 'node:url'
 
 import type {
@@ -313,6 +315,25 @@ export class PluginContext {
     return JSON.parse(await readFile(join(this.publishDir, 'routes-manifest.json'), 'utf-8'))
   }
 
+  #nextVersion: string | null | undefined = undefined
+
+  /**
+   * Get Next.js version that was used to build the site
+   */
+  get nextVersion(): string | null {
+    if (this.#nextVersion === undefined) {
+      try {
+        const serverHandlerRequire = createRequire(posixJoin(this.standaloneRootDir, ':internal:'))
+        const { version } = serverHandlerRequire('next/package.json')
+        this.#nextVersion = version as string
+      } catch {
+        this.#nextVersion = null
+      }
+    }
+
+    return this.#nextVersion
+  }
+
   /** Fails a build with a message and an optional error */
   failBuild(message: string, error?: unknown): never {
     return this.utils.build.failBuild(message, error instanceof Error ? { error } : undefined)

src/build/verification.ts

@@ -47,6 +47,15 @@ export function verifyPublishDir(ctx: PluginContext) {
         `Your publish directory does not contain expected Next.js build output. Please make sure you are using Next.js version (${SUPPORTED_NEXT_VERSIONS})`,
       )
     }
+
+    if (
+      ctx.nextVersion &&
+      !satisfies(ctx.nextVersion, SUPPORTED_NEXT_VERSIONS, { includePrerelease: true })
+    ) {
+      ctx.failBuild(
+        `@netlify/plugin-next@5 requires Next.js version ${SUPPORTED_NEXT_VERSIONS}, but found ${ctx.nextVersion}. Please upgrade your project's Next.js version.`,
+      )
+    }
   }
   if (ctx.buildConfig.output === 'export') {
     if (!ctx.exportDetail?.success) {
@@ -60,14 +69,6 @@ export function verifyPublishDir(ctx: PluginContext) {
   }
 }
 
-export function verifyNextVersion(ctx: PluginContext, nextVersion: string): void | never {
-  if (!satisfies(nextVersion, SUPPORTED_NEXT_VERSIONS, { includePrerelease: true })) {
-    ctx.failBuild(
-      `@netlify/plugin-next@5 requires Next.js version ${SUPPORTED_NEXT_VERSIONS}, but found ${nextVersion}. Please upgrade your project's Next.js version.`,
-    )
-  }
-}
-
 export async function verifyNoAdvancedAPIRoutes(ctx: PluginContext) {
   const apiRoutesConfigs = await getAPIRoutesConfigs(ctx)