Description of problem:

jsonrpc pass unicode objects to vdsm apis when it should pass plain strings:

2015-11-13 20:17:15,690 INFO [dispatcher] (jsonrpc.Executor/0) Run and protect: connectStoragePool(spUUID=u'591475db-6fa9-455d-9c05-7f6e30fb06d5', hostID=1, msdUUID=u'6c77adb1-74fc-4fa9-a0ac-3b5a4b789318', masterVersion=3, domainsMap={u'869b6036-a9ca-43eb-9287-828803822783': u'active', u'6267179b-bd65-43c1-8a1e-f33cf12582fa': u'attached', u'e43d9b66-aef1-49d7-bfb4-bc06ddc9f025': u'attached', u'6c77adb1-74fc-4fa9-a0ac-3b5a4b789318': u'active'}, options=None) [logUtils:48(wrapper)]

In this example, arguments like spUUID are pass as a unicode object
u'591475db-6fa9-455d-9c05-7f6e30fb06d5' instead of the plain string:
'591475db-6fa9-455d-9c05-7f6e30fb06d5'.

These unicode strings may cause failures when combining or formatting them
with non-ascii strings:

>>> "ascii" + "\xd7\x90"
'ascii\xd7\x90'

>>> u"ascii" + "\xd7\x90"
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xd7 in position 0: ordinal not in range(128)

Since u"ascii" is unicode string, Python try to convert "\xd7\x90" assuming
the default encoding (ascii), and fails.

Another example is logging:

>>> import logging
>> logging.error("ascii=%s utf8=%s", u"ascii", "\xd7\x90")
Traceback (most recent call last):
  File "/usr/lib64/python2.7/logging/__init__.py", line 859, in emit
    msg = self.format(record)
  File "/usr/lib64/python2.7/logging/__init__.py", line 732, in format
    return fmt.format(record)
  File "/usr/lib64/python2.7/logging/__init__.py", line 471, in format
    record.message = record.getMessage()
  File "/usr/lib64/python2.7/logging/__init__.py", line 335, in getMessage
    msg = msg % self.args
UnicodeDecodeError: 'ascii' codec can't decode byte 0xd7 in position 0: ordinal not in range(128)

Again, works fine with using string object:

>>> logging.error("ascii=%s utf8=%s", "ascii", "\xd7\x90")
ERROR:root:ascii=ascii utf8=א

The root cause is using the json library from the Python standard library.

>>> import json
>>> json.loads(json.dumps({"key": unicode("\xd7\x90", 'utf8')}))
{u'key': u'\u05d0'}

Here the string "key" was converted to u"key".

When running on Python 2.6, we used the simplejson library, which
does not have this issue:

>>> json.loads(json.dumps({"key": unicode("\xd7\x90", 'utf8')}))
{'key': u'\u05d0'}

Note that "key" is a plain string as it should be.

We do use simplejson when it is available:

# lib/vdsm/compat.py
try:
    # on RHEL/Centos 6.x, the JSON module in the python standard
    # library does not include significant speedups:
    # stdlib is based on simplejson 1.9, speedups were added on 2.0.9.
    # In general, speedups are first found on the
    # simplejson package.
    import simplejson as json
    json  # make pyflakes happy
except ImportError:
    # no big deal, fallback to standard libary
    import json
    json  # yep, this is needed twice.

But we do not require simplejson since this patch:

commit fb1c44af320fbeb99f1cba406eae70e653b6de2f
Author: Yaniv Bronhaim <ybronhei>
Date:   Sun Jun 14 14:03:26 2015 +0300

    Remove el6 specific code from spec

    Change-Id: Ifef95b7c61b8bd8c86ef2642e74275da87659cb8
    Signed-off-by: Yaniv Bronhaim <ybronhei>
    Reviewed-on: https://gerrit.ovirt.org/42317
    Continuous-Integration: Jenkins CI
    Reviewed-by: Dima Kuznetsov <dkuznets>
    Reviewed-by: Dan Kenigsberg <danken>

Since the library is not available, we use fallback to builtin
json.

Version-Release number of selected component (if applicable):
Since 3.5, when running on EL7 or Fedora (both use Python 2.7)

How reproducible:
Always