fix(bazel): Builder should invoke local bazel/iblaze (#28303)

Builder for `@angular/bazel` schematics should not expect bazel/ibazel
to be on the PATH. It should instead invoke the local executable
installed by yarn/npm.

PR Close #28303

packages/bazel/src/builders/bazel.ts

@@ -8,6 +8,7 @@
 
 /// <reference types='node'/>
 import {spawn, spawnSync} from 'child_process';
+import {join} from 'path';
 import {Observable, Subject} from 'rxjs';
 
 export type Executable = 'bazel' | 'ibazel';
@@ -17,7 +18,8 @@ export function runBazel(
     projectDir: string, executable: Executable, command: Command, workspaceTarget: string,
     flags: string[]): Observable<void> {
   const doneSubject = new Subject<void>();
-  const buildProcess = spawn(executable, [command, workspaceTarget, ...flags], {
+  const bin = join(projectDir, 'node_modules', '.bin', executable);
+  const buildProcess = spawn(bin, [command, workspaceTarget, ...flags], {
     cwd: projectDir,
     stdio: 'inherit',
     shell: false,
@@ -35,7 +37,8 @@ export function runBazel(
 }
 
 export function checkInstallation(executable: Executable, projectDir: string) {
-  const child = spawnSync(executable, ['version'], {
+  const bin = join(projectDir, 'node_modules', '.bin', executable);
+  const child = spawnSync(bin, ['version'], {
     cwd: projectDir,
     shell: false,
   });

packages/bazel/src/builders/index.ts

@@ -11,7 +11,7 @@
 import {BuildEvent, Builder, BuilderConfiguration, BuilderContext} from '@angular-devkit/architect';
 import {getSystemPath, resolve} from '@angular-devkit/core';
 import {Observable, of } from 'rxjs';
-import {catchError, map, tap} from 'rxjs/operators';
+import {catchError, map} from 'rxjs/operators';
 
 import {checkInstallation, runBazel} from './bazel';
 import {Schema} from './schema';
@@ -28,7 +28,8 @@ class BazelBuilder implements Builder<Schema> {
     if (!checkInstallation(executable, projectRoot)) {
       throw new Error(
           `Could not run ${executable}. Please make sure that the ` +
-          `"${executable}" command is available in the $PATH.`);
+          `"${executable}" command is installed by running ` +
+          `"npm install" or "yarn install".`);
     }
 
     // TODO: Support passing flags.