Base flags on bootstrapped Chromite branch.

scripts/slave/recipe_modules/chromite/config.py

Index: scripts/slave/recipe_modules/chromite/config.py
diff --git a/scripts/slave/recipe_modules/chromite/config.py b/scripts/slave/recipe_modules/chromite/config.py
index ef39cb3490c4c33317c9e889fcef5e3df892b9f5..daee1840cf7c81773c03042ebce265a9fb40eb90 100644
--- a/scripts/slave/recipe_modules/chromite/config.py
+++ b/scripts/slave/recipe_modules/chromite/config.py
@@ -6,7 +6,7 @@ import os
 import re
 
 from recipe_engine.config import config_item_context, ConfigGroup
-from recipe_engine.config import Dict, Single, Set
+from recipe_engine.config import Dict, Single, List, Set
 
 
 # Regular expression to match branch versions.
@@ -21,8 +21,8 @@ _VERSION_RE = re.compile(r'^.*-(\d+)\.(\d+\.)?B$')
 
 def BaseConfig(CBB_CONFIG=None, CBB_BRANCH=None, CBB_BUILD_NUMBER=None,
                CBB_DEBUG=False, CBB_CLOBBER=False, CBB_BUILDBUCKET_ID=None,
-               CBB_MASTER_BUILD_ID=None, **_kwargs):
-  return ConfigGroup(
+               CBB_MASTER_BUILD_ID=None, CBB_EXTRA_ARGS=None, **_kwargs):
+  cgrp = ConfigGroup(
     # Base mapping of repository key to repository name.
     repositories = Dict(value_type=Set(basestring)),
 
@@ -89,7 +89,10 @@ def BaseConfig(CBB_CONFIG=None, CBB_BRANCH=None, CBB_BUILD_NUMBER=None,
       git_cache_dir = Single(basestring),
 
       # If supplied, forward to cbuildbot as '--buildbucket-id'
-      buildbucket_id = Single(basestring, empty_val=CBB_BUILDBUCKET_ID)
+      buildbucket_id = Single(basestring, empty_val=CBB_BUILDBUCKET_ID),
+
+      # Extra arguments passed to cbuildbot.
+      extra_args = List(basestring),
     ),
 
     # A list of branches whose Chromite version is "old". Old Chromite
@@ -119,6 +122,11 @@ def BaseConfig(CBB_CONFIG=None, CBB_BRANCH=None, CBB_BUILD_NUMBER=None,
     git_cache_min_branch_version = Single(int, empty_val=8829),
   )
 
+  if CBB_EXTRA_ARGS:
+    cgrp.cbb.extra_args = CBB_EXTRA_ARGS

[nxia1, 2016/09/28 21:45:31]

any reason for not combining this with line 95? we can pass in CBB_EXTRA_ARGS=[]
as the default value and combine them?

[dnj, 2016/09/28 22:52:16]

List doesn't have a default value.

+  return cgrp
+
+
 config_ctx = config_item_context(BaseConfig)
 
 
@@ -148,9 +156,19 @@ def base(c):
     'factory-nyan-5772.B',
   ))
 
+  # Determine if we're manually specifying the tryjob branch in the extra
+  # args. If we are, use that as the branch version.
+  chromite_branch = c.chromite_branch
+  try:
+    branch_flag_idx = list(c.cbb.extra_args).index('--branch') + 1

[nxia1, 2016/09/28 21:45:31]

what happens when people pass in '--branch=master'? is it converted properly to
'--branch master' somewhere? 

[dnj, 2016/09/28 22:52:16]

Ugh is that something people do? I'll fix.

+    if branch_flag_idx < len(c.cbb.extra_args):
+      chromite_branch = c.cbb.extra_args[branch_flag_idx]

[nxia1, 2016/09/28 22:00:03]

and I'm confused why we can't overwrite c.chromite_branch by the chromite_branch
got from the extra_args.

[dnj, 2016/09/28 22:52:16]

c.chrome_branch controls which branch of Chromite is checked out. If a user
specifies "master" but tells it to use a separate branch via "extra_args", I
don't want the recipe to preempt them. There are use cases where this might be
desired.

If a user wants to not bootstrap, they should just specify "cbb_branch" instead
of using extra_args.

[nxia1, 2016/09/29 00:36:44]

Look I didn't find the cbb_branch settings in tryserver and chromiumOS. There's
cbb_branch settings in chromeos*. is that why we didn't get the right branch
version so always passed in --git-cache-dir?

[nxia1, 2016/09/29 00:37:52]

Look -> Looks like :)

+  except ValueError:
+    pass
+
   # Resolve branch version, if available.
   assert c.chromite_branch, "A Chromite branch must be configured."
-  version = _VERSION_RE.match(c.chromite_branch)
+  version = _VERSION_RE.match(chromite_branch)
   if version:
     c.branch_version = int(version.group(1))