Docker shell module failed in the latest sonic-mgmt

[msosyak]

Description
The task with sell type docker always fails on the latest sonic-mgmt, example:

- name: Gather information from lldp
  lldp:
  vars:
    ansible_shell_type: docker
    ansible_python_interpreter: docker exec -i lldp python

Steps to reproduce the issue:

1. run dip_sip or lag_2 CT

Describe the results you received:

TASK [test : Gathering peer VM information from lldp] **************************
task path: /var/user/jenkins/bfn-sonic-mgmt/ansible/roles/test/tasks/lag_2.yml:26
Thursday 28 November 2019  10:28:47 +0000 (0:00:00.263)       0:00:26.753 ***** 
The full traceback is:
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/ansible/executor/task_executor.py", line 145, in run
    res = self._execute()
  File "/usr/local/lib/python2.7/dist-packages/ansible/executor/task_executor.py", line 612, in _execute
    self._set_connection_options(variables, templar)
  File "/usr/local/lib/python2.7/dist-packages/ansible/executor/task_executor.py", line 1012, in _set_connection_options
    self._set_plugin_options('shell', final_vars, templar, task_keys)
  File "/usr/local/lib/python2.7/dist-packages/ansible/executor/task_executor.py", line 978, in _set_plugin_options
    plugin.set_options(task_keys=task_keys, var_options=options)
  File "/usr/local/lib/python2.7/dist-packages/ansible/plugins/shell/__init__.py", line 70, in set_options
    env = self.get_option('environment')
  File "/usr/local/lib/python2.7/dist-packages/ansible/plugins/__init__.py", line 60, in get_option
    raise KeyError(to_native(e))
KeyError: 'Requested entry (plugin_type: shell plugin: docker setting: environment ) was not defined in configuration.'

fatal: [cab18-2-dut]: FAILED! => {
    "msg": "Unexpected failure during module execution.", 
    "stdout": ""
}

Describe the results you expected:

Additional information you deem important:

**Output of `show version`:**

```

SONiC Software Version: SONiC.HEAD.488-dirty-20191127.082217
Distribution: Debian 9.11
Kernel: 4.9.0-9-2-amd64
Build commit: 7622a30d
Build date: Wed Nov 27 11:15:51 UTC 2019
Built by: johnar@jenkins-worker-11

```

**Attach debug file `sudo generate_dump`:**

```
(paste your output here)
```

[msosyak]

I have tried to update the python docker module to the latest as we still have docker-py=1.6.0 when ansible requires docker>= 1.7.0 but this did not help me.
https://docs.ansible.com/ansible/latest/scenario_guides/guide_docker.html#requirements

[msosyak]

As lldp module is run on sonic host with custom python interpreter ansible_python_interpreter: docker exec -i lldp python I've tried to commend ansible_shell_type: docker and this helps me.

[msosyak]

@nazariig I see you are the author of this line ansible_shell_type: docker
Could you comment?

[nazariig]

@nazariig I see you are the author of this line ansible_shell_type: docker
Could you comment?

@msosyak This module allows you to execute commands directly in docker on the remote host (inventory)
plugin: https://github.com/Azure/sonic-mgmt/blob/master/ansible/shell_plugins/docker.py
FYI: https://docs.ansible.com/ansible/latest/plugins/shell.html

[nazariig]

@msosyak please check this: #1213 and #1225

[lguohan]

@qiluo-msft is the original author of docker shell plugin, i think i might break the plugin when upgrading 2.8.7. I do not know if it is still necessary. if you are able to run the lldp module successfully, then we no longer need ansible_shell_type: docker

[lguohan]

I did some test. for lldp module, you can remove both lines.

    ansible_shell_type: docker
    ansible_python_interpreter: docker exec -i lldp python

I think we have lldpctl in sonic base image.