uri module enforces Headers in camel-case (explicit the documentation)

[axel3rd]

SUMMARY

Origin: adapter-aws-lambda-serverless #62.

uri module enforce headers written in camel-case, even if filled otherwise (and written as filled in the debug logs).

The documentation should explicit that, avoiding tricky troubleshooting.

ISSUE TYPE

• Docs Pull Request

COMPONENT NAME

uri

ADDITIONAL INFORMATION

Proof:

1. Create a Python server which dump request which listen on 8000 port
2. Write simple playbook and execute it

- name: Test
  hosts: localhost
  tasks:
  - name: Headers Proof
    uri:
      url: http://localhost:8000
      headers:
        X-SoMe-HeADer: FaKe-VaLue

Output produced:

Host: localhost:8000
X-Some-Header: FaKe-VaLue
Connection: close
User-Agent: ansible-httpget

[sivel]

This is an implementation detail of how python transmits headers. We have no control over this behavior, and since it is an implementation detail which could change, and the RFC states that header names are case insensitive, I don't think this isn't something we should document.

[axel3rd]

@sivel : I understand the point of view.

But for avoid some lost of time in this kind of troubleshooting (They are written not modified in -vvv logs ^^), having a word about that somewhere could help IMO.

Perhaps adding a note could be relevant ?

ansible/lib/ansible/modules/uri.py

Lines 195 to 198 in 11f1177

	notes:
	- The dependency on httplib2 was removed in Ansible 2.1.
	- The module returns all the HTTP headers in lower-case.
	- For Windows targets, use the M(ansible.windows.win_uri) module instead.

 notes: 
   - The dependency on httplib2 was removed in Ansible 2.1. 
   - The module sends all the HTTP headers in camel-case. 
   - The module returns all the HTTP headers in lower-case. 
   - For Windows targets, use the M(ansible.windows.win_uri) module instead. 

?

[sivel]

The problem is that the behavior is dictated by Python, and it's not considered a feature, it's an implementation detail. The behavior is not mentioned at all in the Python docs. Get python to commit to it being a feature, and documenting the behavior, and I'd be open to accepting docs that point to that and convey it here.

Basically what I am saying, is that until python commits to that behavior being stable and documents it, we shouldn't either, because it should not be relied on as stable, and could change.

[axel3rd]

I will try to manage this strategy/documentation point in Python ecosystem.

[jborean93]

Closing as per the above, please reopen the PR if you get any response back from the CPython team.

[axel3rd]

For history: Python bug issue43331 / PR 24661.