git-cl: Tell users to set SKIP_GCE_AUTH_FOR_GIT=1 when running on cloudtop.

Bug: 1059141
Change-Id: I0a4501946014bd567548fb5396c3dd761606a9bf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2091584
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Anthony Polito <apolito@google.com>

gerrit_util.py

@@ -101,6 +101,8 @@ class Authenticator(object):
     # which then must use it.
     if LuciContextAuthenticator.is_luci():
       return LuciContextAuthenticator()
+    # TODO(crbug.com/1059384): Automatically detect when running on cloudtop,
+    # and use CookiesAuthenticator instead.
     if GceAuthenticator.is_gce():
       return GceAuthenticator()
     return CookiesAuthenticator()
@@ -465,6 +467,10 @@ def ReadHttpResponse(conn, accept_statuses=frozenset([200])):
       host = auth_match.group(1) if auth_match else conn.req_host
       print('Authentication failed. Please make sure your .gitcookies '
             'file has credentials for %s.' % host)
+    # TODO(crbug.com/1059384): Automatically detect when running on cloudtop.
+    if isinstance(Authenticator.get(), GceAuthenticator):
+      print('If you\'re on a cloudtop instance, export '
+            'SKIP_GCE_AUTH_FOR_GIT=1 in your env.')
     print('Try:\n  git cl creds-check')
 
   reason = '%s: %s' % (response.reason, contents)

git_cl.py

@@ -3396,14 +3396,16 @@ def CMDcreds_check(parser, args):
   # Code below checks .gitcookies. Abort if using something else.
   authn = gerrit_util.Authenticator.get()
   if not isinstance(authn, gerrit_util.CookiesAuthenticator):
-    if isinstance(authn, gerrit_util.GceAuthenticator):
-      DieWithError(
-          'This command is not designed for GCE, are you on a bot?\n'
-          'If you need to run this on GCE, export SKIP_GCE_AUTH_FOR_GIT=1 '
-          'in your env.')
-    DieWithError(
+    message = (
         'This command is not designed for bot environment. It checks '
         '~/.gitcookies file not generally used on bots.')
+    # TODO(crbug.com/1059384): Automatically detect when running on cloudtop.
+    if isinstance(authn, gerrit_util.GceAuthenticator):
+      message += (
+          '\n'
+          'If you need to run this on GCE or a cloudtop instance, '
+          'export SKIP_GCE_AUTH_FOR_GIT=1 in your env.')
+    DieWithError(message)
 
   checker = _GitCookiesChecker()
   checker.ensure_configured_gitcookies()