Pass args in file from task_runner to run_isolated

client/run_isolated.py

Index: client/run_isolated.py
diff --git a/client/run_isolated.py b/client/run_isolated.py
index 7c3f063793c8f1356e4ceeb5697043fed212788a..c8343c0a601c60d30ed8f4a6899eba80f2e7282b 100755
--- a/client/run_isolated.py
+++ b/client/run_isolated.py
@@ -27,10 +27,12 @@ state of the host to tasks. It is written to by the swarming bot's
 on_before_task() hook in the swarming server's custom bot_config.py.
 """
 
-__version__ = '0.8.5'
+__version__ = '0.8.6'
 
+import argparse
 import base64
 import collections
+import json
 import logging
 import optparse
 import os
@@ -758,9 +760,33 @@ def create_option_parser():
   return parser
 
 
-def main(args):
+def parse_args(args):
+  # Create a fake mini-parser just to get out the "-a" command. Note that
+  # it's not documented here; instead, it's documented in create_option_parser

[M-A Ruel, 2016/10/24 20:25:09]

It's not?

[aludwin, 2016/10/24 21:03:53]

Whoops, I forgot to actually document it in create_option_parser. Fixed.

+  # even though that parser will never actually get to parse it. This is
+  # because -f is exclusive with all other options and arguments.
+  file_argparse = argparse.ArgumentParser()

[M-A Ruel, 2016/10/24 20:25:09]

file_argparse = argparse.ArgumentParser(add_help=False)

Yep it's not documented, why do you ask? :P

[aludwin, 2016/10/24 21:03:53]

Done.

+  file_argparse.add_argument("-a", "--argsfile")
+  (file_args, nonfile_args) = file_argparse.parse_known_args(args)
+  if not file_args.argsfile == None:
+    if len(nonfile_args) > 0:
+      file_argparse.error('Can\'t specify --argsfile with'
+                          'any other arguments (%s)' % nonfile_args)
+    try:
+      with open(file_args.argsfile, 'r') as f:
+        args = json.loads(f.read())
+    except Exception as e:

[M-A Ruel, 2016/10/24 20:25:09]

except (IOError, OSError, ValueError): as e:
  print >> sys.stderr, 'Couldn't read arguments: %s' % e
  sys.exit(1)

well, I'd prefer to return instead of sys.exit..

[aludwin, 2016/10/24 21:03:53]

We don't need to sys.exit or return. After this line, "args" will be empty so
when we call parser.parse_args(args), we'll get the help and error out then.
I'll add a comment.

+      print "Couldn't read arguments: %s" % e
+
+  # Even if we failed to read the args, just call the normal parser now since it
+  # will print the correct help message.
   parser = create_option_parser()
   options, args = parser.parse_args(args)
+  return (parser, options, args)
+
+
+def main(args):
+  (parser, options, args) = parse_args(args)
 
   isolated_cache = isolateserver.process_cache_options(options)
   if options.clean:
@@ -829,4 +855,5 @@ if __name__ == '__main__':
   # Ensure that we are always running with the correct encoding.
   fix_encoding.fix_encoding()
   file_path.enable_symlink()
+
   sys.exit(main(sys.argv[1:]))