Fix vpython caching in trigger.py script.

scripts/trigger.py

@@ -24,6 +24,47 @@ def parse_args():
     return parser.parse_known_args()
 
 
+# Taken from:
+# https://chromium.googlesource.com/chromium/src/tools/mb/+/2192df66cd0ed214bcfbfd387ad0c5c8c0a21eb1/mb.py#586
+def add_base_software(swarming_args):
+    # HACK(iannucci): These packages SHOULD NOT BE HERE.
+    # Remove method once Swarming Pool Task Templates are implemented.
+    # crbug.com/812428
+
+    # Add in required base software. This should be kept in sync with the
+    # `chromium_swarming` recipe module in build.git. All references to
+    # `swarming_module` below are purely due to this.
+    cipd_packages = [
+        ('infra/python/cpython/${platform}', 'version:2.7.15.chromium14'),
+        ('infra/tools/luci/logdog/butler/${platform}',
+         'git_revision:e1abc57be62d198b5c2f487bfb2fa2d2eb0e867c'),
+        ('infra/tools/luci/vpython-native/${platform}',
+         'git_revision:e317c7d2c17d4c3460ee37524dfce4e1dee4306a'),
+        ('infra/tools/luci/vpython/${platform}',
+         'git_revision:e317c7d2c17d4c3460ee37524dfce4e1dee4306a'),
+    ]
+
+    for pkg, vers in cipd_packages:
+        swarming_args.append('--cipd-package=.swarming_module:%s:%s' % (pkg, vers))
+
+    # Add packages to $PATH
+    swarming_args.extend([
+        '--env-prefix=PATH',
+        '.swarming_module',
+        '--env-prefix=PATH',
+        '.swarming_module/bin',
+    ])
+
+    # Add cache directives for vpython.
+    vpython_cache_path = '.swarming_module_cache/vpython'
+    swarming_args.extend([
+        '--named-cache=swarming_module_cache_vpython',
+        vpython_cache_path,
+        '--env-prefix=VPYTHON_VIRTUALENV_ROOT',
+        vpython_cache_path,
+    ])
+
+
 def main():
     args, unknown = parse_args()
     path = args.gn_path.replace('\\', '/')
@@ -47,19 +88,20 @@ def main():
     print('Got an isolated SHA of %s' % sha)
     swarming_script_path = os.path.join('tools', 'swarming_client', 'swarming.py')
 
-    swarmings_args = [
+    swarming_args = [
         'python', swarming_script_path, 'trigger', '-S', 'chromium-swarm.appspot.com', '-I',
         'isolateserver.appspot.com', '-d', 'os', args.os_dim, '-d', 'pool', args.pool, '-d', 'gpu',
         args.gpu_dim,
         '--shards=%d' % args.shards, '-s', sha
     ]
 
-    if unknown:
-        swarmings_args += ["--"] + unknown
+    add_base_software(swarming_args)
 
+    if unknown:
+        swarming_args += ["--"] + unknown
 
-    print(' '.join(swarmings_args))
-    subprocess.call(swarmings_args)
+    print(' '.join(swarming_args))
+    subprocess.call(swarming_args)
     return 0