From 9e338e1baae8c738e5666d48893dc761aaecbf0e Mon Sep 17 00:00:00 2001
From: Charles Lyding <19598772+clydin@users.noreply.github.com>
Date: Fri, 17 Oct 2025 14:41:50 -0400
Subject: [PATCH] refactor(@angular/build): allow Bazel to inject a custom
 esbuild plugin

Introduces a mechanism to dynamically load a custom esbuild plugin when the application builder is executed within a Bazel environment.

This is enabled by a new `bazelEsbuildPluginPath` option, which is derived from the `NG_INTERNAL_ESBUILD_PLUGINS_DO_NOT_USE` environment variable. The path is only resolved if the `BAZEL_BINDIR` and `JS_BINARY__EXECROOT` environment variables are also present, ensuring the logic is only active during a Bazel build.

The builder dynamically imports the plugin from the specified path and adds it to the esbuild pipeline, allowing for build-system-specific customizations.

(cherry picked from commit ec739d79e042c2b33fd84ed9aede7c88a82e167e)
---
 .../angular/build/src/builders/application/index.ts    | 10 +++++++++-
 .../angular/build/src/utils/environment-options.ts     |  8 ++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/packages/angular/build/src/builders/application/index.ts b/packages/angular/build/src/builders/application/index.ts
index 8f11f2fd8001..b83e3b48f270 100644
--- a/packages/angular/build/src/builders/application/index.ts
+++ b/packages/angular/build/src/builders/application/index.ts
@@ -14,7 +14,7 @@ import { BuildOutputFileType } from '../../tools/esbuild/bundler-context';
 import { createJsonBuildManifest, emitFilesToDisk } from '../../tools/esbuild/utils';
 import { colors as ansiColors } from '../../utils/color';
 import { deleteOutputDir } from '../../utils/delete-output-dir';
-import { useJSONBuildLogs } from '../../utils/environment-options';
+import { bazelEsbuildPluginPath, useJSONBuildLogs } from '../../utils/environment-options';
 import { purgeStaleBuildCache } from '../../utils/purge-cache';
 import { assertCompatibleAngularVersion } from '../../utils/version';
 import { runEsBuildBuildAction } from './build-action';
@@ -56,6 +56,14 @@ export async function* buildApplicationInternal(
     return;
   }
 
+  if (bazelEsbuildPluginPath) {
+    extensions ??= {};
+    extensions.codePlugins ??= [];
+
+    const { default: bazelEsbuildPlugin } = await import(bazelEsbuildPluginPath);
+    extensions.codePlugins.push(bazelEsbuildPlugin);
+  }
+
   const normalizedOptions = await normalizeOptions(context, projectName, options, extensions);
 
   if (!normalizedOptions.outputOptions.ignoreServer) {
diff --git a/packages/angular/build/src/utils/environment-options.ts b/packages/angular/build/src/utils/environment-options.ts
index ea06fea2d09f..d830a5095959 100644
--- a/packages/angular/build/src/utils/environment-options.ts
+++ b/packages/angular/build/src/utils/environment-options.ts
@@ -112,3 +112,11 @@ export const useComponentTemplateHmr =
 const partialSsrBuildVariable = process.env['NG_BUILD_PARTIAL_SSR'];
 export const usePartialSsrBuild =
   isPresent(partialSsrBuildVariable) && isEnabled(partialSsrBuildVariable);
+
+const bazelBinDirectory = process.env['BAZEL_BINDIR'];
+const bazelExecRoot = process.env['JS_BINARY__EXECROOT'];
+
+export const bazelEsbuildPluginPath =
+  bazelBinDirectory && bazelExecRoot
+    ? process.env['NG_INTERNAL_ESBUILD_PLUGINS_DO_NOT_USE']
+    : undefined;