Error in huge template - how to find the culprit?

[Dick Visser]

Hii,

I have a template that has a lot of variables and control structures. I get an error during the playbook run:

fatal: [prod_nagios2]: FAILED! => changed=false
  msg: |-
    AnsibleError: Unexpected templating type error occurred on (

    <huge template content here>

): 'NoneType' object is not iterable

The content of the template is 800 lines, about 36kB, with 100+ variables.

Anyone have an idea where to start looking?

[Dick Visser]

with extra debugging:

The full traceback is:
Traceback (most recent call last):
  File "/Users/dick.visser/foo/venv/lib/python3.11/site-packages/ansible/template/__init__.py", line 1160, in do_template
    res = j2_concat(rf)
          ^^^^^^^^^^^^^
  File "<template>", line 764, in root
TypeError: 'NoneType' object is not iterable

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/dick.visser/foo/venv/lib/python3.11/site-packages/ansible/plugins/action/template.py", line 150, in run
    resultant = templar.do_template(template_data, preserve_trailing_newlines=True, escape_backslashes=False)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/dick.visser/foo/venv/lib/python3.11/site-packages/ansible/template/__init__.py", line 1171, in do_template
    raise AnsibleError("Unexpected templating type error occurred on (%s): %s" % (to_native(data), to_native(te)))
ansible.errors.AnsibleError: Unexpected templating type error occurred on (

<huge template content>

I guessed that "line 764" would be the location in the template, but at that place nothing seems relevant....

[Matt Martz]

Line 764 in root is referencing the python code that jinja ultimately generates to run. So there isn't really an easy way to map that back to the template itself.

I have a tool that can ingest a jinja template, and print out that python code. It's possible you might be able to visually understand what the python code is doing, and trace that back to a line in your jinja template. You can find it at:

https://gist.github.com/sivel/6c93326b4cadd127bceb9ca6bb7e204a

Run like:  python j2generated.py < template.j2

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Matt Martz
@sivel
sivel.net

[Dick Visser]

thx, but that failed on missing filters.

In any case, I stripped out al for loops and found the problem.

The deployer had commented out list items, but did not leave any.

So:

foobar:

  - bar

  - baz

  - bor

was in the config as:

foobar:

#  - bar

#  - baz

#  - bor

which meant it wasn't a list anymore, but null instead, and thus None in python...

Dick

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