Fix conflicts in ansible tmp dir for parallel run

[wangxin]

Description of PR

Summary:
Fixes # (issue)

Script test_bgp_gr_helper.py occasionally failed with:

08:57:05 ERROR test_nbrconn.py:check_results:22: failed_results => {                                                                                                                                                                          
  "VM0107": [                                                                                                                                                                                                                                 
    {                                                                                                                                                                                                                                         
      "msg": "Unexpected failure during module execution.",                                                                                                                                                                                   
      "failed": true,                                                                                                                                                                                                                         
      "exception": "Traceback (most recent call last):\n  File \"/usr/local/lib/python2.7/dist-packages/ansible/executor/task_executor.py\", line 145, in run\n    res = self._execute()\n  File \"/usr/local/lib/python2.7/dist-packages/ansi
ble/executor/task_executor.py\", line 664, in _execute\n    result = self._handler.run(task_vars=variables)\n  File \"/usr/local/lib/python2.7/dist-packages/ansible/plugins/action/eos.py\", line 105, in run\n    result = super(ActionModul
e, self).run(task_vars=task_vars)\n  File \"/usr/local/lib/python2.7/dist-packages/ansible/plugins/action/network.py\", line 48, in run\n    result = super(ActionModule, self).run(task_vars=task_vars)\n  File \"/usr/local/lib/python2.7/di
st-packages/ansible/plugins/action/normal.py\", line 46, in run\n    result = merge_hash(result, self._execute_module(task_vars=task_vars, wrap_async=wrap_async))\n  File \"/usr/local/lib/python2.7/dist-packages/ansible/plugins/action/__i
nit__.py\", line 809, in _execute_module\n    (module_style, shebang, module_data, module_path) = self._configure_module(module_name=module_name, module_args=module_args, task_vars=task_vars)\n  File \"/usr/local/lib/python2.7/dist-packag
es/ansible/plugins/action/__init__.py\", line 203, in _configure_module\n    environment=final_environment)\n  File \"/usr/local/lib/python2.7/dist-packages/ansible/executor/module_common.py\", line 1023, in modify_module\n    environment
=environment)\n  File \"/usr/local/lib/python2.7/dist-packages/ansible/executor/module_common.py\", line 878, in _find_module_utils\n    os.rename(cached_module_filename + '-part', cached_module_filename)\nOSError: [Errno 2] No such file 
or directory\n",                                                                                                                                                                                                                              
      "_ansible_no_log": false,                                                                                                                                                                                                               
      "stdout": ""                                                                                                                                                                                                                            
    }                                                                                                                                                                                                                                         
  ]                                                                                                                                                                                                                                           
}                                                                                                                                                                                                                                             
FAILED

This is because of conflicts in parallel run for configuring multiple VMs in bgp/conftest.py. This PR is to fix the conflict issue.

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• Test case(new/improvement)

Approach

What is the motivation for this PR?

Parallel execution by multiprocessing is used in bgp/conftest.py for
configuring multiple VM nodes. However, all the subprocesses are
using same tmp dir for ansiballz related operation. There could be
conflicts.

How did you do it?

This change added a decorator for resetting ansible tmp folder for each subprocess. Then each subprocess has its own unique tmp folder.

How did you verify/test it?

Used temp debug code to verify that each subprocess is using unique temp dir.
Verified that temp directories are cleared after test.
Test run bgp/test_bgp_gr_helper.py multiple times.

Any platform specific information?

Supported testbed topology if it's a new test case?

Documentation

[lgtm-com]

This pull request introduces 1 alert when merging 282b43c into bdfd25b - view on LGTM.com

new alerts:

• 1 for Module is imported more than once

[yxieca]

maybe move imports to the top of the file with other imports? os was imported before and LGTM is complaining about that.

[wangxin]

Moved import os, shutil, tempfile to top of file. Since importing ansible is just for updating temp folder for sub-processes, this importing is still kept here.