Fix crypttab python3 compatibility issue

[jpiron]

SUMMARY

The crypttab module doesn't work with Python3.

ISSUE TYPE

• Bugfix Pull Request

COMPONENT NAME

crypttab

ANSIBLE VERSION

ansible 2.5.0 (crypttab_python3_compatibility_fix 8c4532203c) last updated 2017/09/16 14:27:26 (GMT +200)
  config file = None
  configured module search path = [u'/home/john/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /home/john/workspace/ansible/lib/ansible
  executable location = /home/john/workspace/ansible/bin/ansible
  python version = 2.7.12 (default, Nov 19 2016, 06:48:10) [GCC 5.4.0 20160609]

ADDITIONAL INFORMATION

Here is how to reproduce:
Python2 working case:

./hacking/test-module -I 'ansible_python_interpreter=/usr/bin/python2' -m lib/ansible/modules/system/crypttab.py -a '{"name":"foo","backing_device":"/dev/bar","state":"present","path":"/tmp/crypttab"}'
* including generated source, if any, saving to: /home/john/.ansible_module_generated
* ansiballz module detected; extracted module source to: /home/john/debug_dir
***********************************
RAW OUTPUT

{"group": "john", "name": "foo", "backing_device": "/dev/bar", "warnings": ["Module did not set no_log for password"], "changed": true, "invocation": {"module_args": {"name": "foo", "backing_device": "/dev/bar", "state": "present", "path": "/tmp/crypttab", "password": null, "opts": null}}, "state": "file", "gid": 1000, "mode": "0664", "msg": "added line", "owner": "john", "path": "/tmp/crypttab", "password": null, "uid": 1000, "opts": null, "size": 13}


***********************************
PARSED OUTPUT
{
    "backing_device": "/dev/bar", 
    "changed": true, 
    "gid": 1000, 
    "group": "john", 
    "invocation": {
        "module_args": {
            "backing_device": "/dev/bar", 
            "name": "foo", 
            "opts": null, 
            "password": null, 
            "path": "/tmp/crypttab", 
            "state": "present"
        }
    }, 
    "mode": "0664", 
    "msg": "added line", 
    "name": "foo", 
    "opts": null, 
    "owner": "john", 
    "password": null, 
    "path": "/tmp/crypttab", 
    "size": 13, 
    "state": "file", 
    "uid": 1000, 
    "warnings": [
        "Module did not set no_log for password"
    ]
}

Python3 not working case:

./hacking/test-module -I 'ansible_python_interpreter=/usr/bin/python3' -m lib/ansible/modules/system/crypttab.py -a '{"name":"foo","backing_device":"/dev/bar","state":"present","path":"/tmp/crypttab"}'
* including generated source, if any, saving to: /home/john/.ansible_module_generated
* ansiballz module detected; extracted module source to: /home/john/debug_dir
***********************************
RAW OUTPUT

Traceback (most recent call last):
  File "/home/john/debug_dir/ansible_module_crypttab.py", line 372, in <module>
    main()
  File "/home/john/debug_dir/ansible_module_crypttab.py", line 172, in main
    f.write(str(crypttab))
TypeError: a bytes-like object is required, not 'str'

***********************************
INVALID OUTPUT FORMAT

Traceback (most recent call last):
  File "./hacking/test-module", line 220, in runtest
    results = json.loads(out)
  File "/usr/lib/python2.7/json/__init__.py", line 339, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python2.7/json/decoder.py", line 364, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python2.7/json/decoder.py", line 382, in raw_decode
    raise ValueError("No JSON object could be decoded")
ValueError: No JSON object could be decoded

[ansibot]

cc @groks
click here for bot help

[groks]

shipit

[abadger]

We want to do the opposite. open the file in binary mode and explicitly change the data to bytes. This gives us greater control over the encoding and what to do on errors.

from ansible.module_utils._text import to_bytes
[...]
            f = open(path, 'wb')
            f.write(to_bytes(crypttab, errors='surrogate_or_strict'))

[abadger]

@jpiron Is changing your PR as I mentioned above something you'll have the time to do?

[jpiron]

Indeed much better than my naïve fix :)
I updated the PR accordingly.

[abadger]

Thanks @jpiron Merged to devel and cherry-picked to stable-2.4 for the 2.4.1 release.