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2020-05-13 Ansible

Enter Python Debugger From Running An Ansible Playbook

Enter the python debugger from Running an Ansible Playbook#

I have some other strategies below but when we really want to do it do get access to pdb or ipdb when running a play. The ansible developer guide has a section on debugging.

Ansible modules don’t work like any other python files. They are wrapped up with a script and put into a zip file. Why?

The article mentions Simple Debugging using epdb

Simple is better than complex so let us try it

Simple Debugging#

Apparently all you need to do is:

pip install epdb

Into your virtual env.

Then add this line anywhere in the module where you have an issue.

import epdb; epdb.serve()

The line where you have the issue can usually be found by running your playbook in verbose mode -vvvv

From the epdb docs:

To debug code that is either running on a remote system, or in a process that isn’t attached to your tty you can use epdb in server mode

Now run your playbook and it should hang at a point. So now you can connect to the server with:

ipython
import epdb
epdb.connect()

It worked for me but I couldn’t control it…by stepping through. Ie c, s and n did not work. Not even h (help) so I don’t think it ever got into epdb

What you can do is debug by outputing to the terminal - but not print() statements do not work in modules so it is better to use:

raise Exception(some_value)

Debug Strategy#

It depends on your play strategy.

Set

- hosts: all
  connection: local
  strategy: debug

It will then brek on a failing task:

[localhost] TASK: create org (debug)>

You can then get the output of the json args sent to a module or task. Get the task arguments as JSON with:

{
    'org_name': 'TEST0002',
    'full_name': 'Test VCD ORG',
    'is_enabled': 'true',
    'state': 'present',
    '_ansible_check_mode': False,
    '_ansible_no_log': False,
    '_ansible_debug': False,
    '_ansible_diff': False,
    '_ansible_verbosity': 0,
    '_ansible_version': '2.9.7',
    '_ansible_module_name': 'vcd_org', '_ansible_syslog_facility': 'LOG_USER', '_ansible_selinux_special_fs': ['fuse', 'nfs', 'vboxsf', 'ramfs', '9p', 'vfat'], '_ansible_string_conversion_action': 'warn', '_ansible_socket': None,
    '_ansible_shell_executable': '/bin/sh', '_ansible_keep_remote_files': False,
    '_ansible_tmpdir': '/Users/stephen/.ansible/tmp/ansible-tmp-1588670617.1317708-64312-102300914438839/', '_ansible_remote_tmp': '~/.ansible/tmp'
}

More things you can do is avaialable in the ansible debugger docs

Module Utils#

Module utils can be accessed via the ansible.module_utils.<your_name_here>

The problem is when runnign the module directly the module utils won’t be in the python path and you will get an error

python modules/vcd_org.py ./test_args.json
Traceback (most recent call last):
File "modules/vcd_org.py", line 102, in <module>
    from ansible.module_utils.vcd import VcdAnsibleModule
ModuleNotFoundError: No module named 'ansible.module_utils.vcd'

how to get the ansible search path when running module directly

You can find the path with:

ansible-config dump| grep MODULE_UTILS_PATH

However it looks to be a limitation of ansible to bring in the custom ansible module_utils as per the google forum

Hacky solution#

Copy the files from module utils into your module library and then just update the references of from ansible.module_utils.<package>. to from <package>

Sources#