Ansible, loop, register, and stdout - ansible

Question

I have a playbook that looks like this:
- hosts: host1
gather_facts: false
tasks:
- name: "Loop"
command: "echo {{ item }}"
with_items: [ 0, 2, 4, 6, 8, 10 ]
register: hello
- debug: "msg={{ hello.results }}"
Everything works correctly, and the output is returned, but there is tons and tons of output. It turns out that this:
- debug: "msg={{ hello.results.1.stdout }}"
does exactly what I want -- just grab the stdout from the command -- but only for one of the six times through the loop.
What I really want/need to do is this:
- debug: "msg={{ hello.results.*.stdout }}"
where it goes into the hello structure, accesses the results entry, goes to each member of that array, and pulls out the stdout value.
Is this possible?
UPDATE
- hosts: host1
gather_facts: false
tasks:
- name: "Loop"
command: "echo {{ item }}"
with_items: [ 0, 2, 4, 6, 8, 10 ]
register: hello
- debug:
msg: "{{item.stdout}}"
with_items: "{{hello.results}}"
is no less verbose than my original example.
TASK [debug] *******************************************************************
ok: [host1] => (item={'_ansible_parsed': True, 'stderr_lines': [], u'cmd': [
u'echo', u'0'], u'end': u'2018-01-02 20:53:08.916774', '_ansible_no_log': False
, u'stdout': u'0', '_ansible_item_result': True, u'changed': True, 'item': 0,
u'delta': u'0:00:00.002137', u'stderr': u'', u'rc': 0, u'invocation': {u'module_
args': {u'warn': True, u'executable': None, u'_uses_shell': False, u'_raw_params
': u'echo 0', u'removes': None, u'creates': None, u'chdir': None, u'stdin': Non
e}}, 'stdout_lines': [u'0'], u'start': u'2018-01-02 20:53:08.914637', 'failed':
False}) => {
"item": {
"changed": true,
"cmd": [
"echo",
"0"
],
"delta": "0:00:00.002137",
"end": "2018-01-02 20:53:08.916774",
"failed": false,
"invocation": {
"module_args": {
"_raw_params": "echo 0",
"_uses_shell": false,
"chdir": null,
"creates": null,
"executable": null,
"removes": null,
"stdin": null,
"warn": true
}
},
"item": 0,
"rc": 0,
"start": "2018-01-02 20:53:08.914637",
"stderr": "",
"stderr_lines": [],
"stdout": "0",
"stdout_lines": [
"0"
]
},
"msg": "0"
}
I get 6 copies of the above construct.
It feels like I'm close but I'm still doing something wrong. I see "msg": "0" at the bottom, which is what I want. I just don't want the rest of it.

Answer 1

Solution:
- debug: "msg={{ hello.results | map(attribute='stdout') | join('\n') }}"
Remark:
By default, Ansible will print visible \n two-character sequences instead of wrapping the lines, so either use a callback plugin for a human readable output (example) or verify the method with:
- copy:
content: "{{ hello.results | map(attribute='stdout') | join('\n') }}"
dest: ./result.txt
and check the contents of the result.txt.

Answer 2

I have used the keyword loop to get stdout from all iterations of the previous loop:
loop: "{{ hello | json_query('results[*].stdout') }}"
I find json_query easiest to use in such register-loop situations. Official documentation can be found here ==> json-query-filter

Answer 3

Sure. The ansible website has documentation that explains how to use register in a loop. You just need to iterate over the hello.results array, as in:
- debug:
msg: "{{item.stdout}}"
with_items: "{{hello.results}}"

Answer 4

What about:
- debug: "msg={{ item.stdout }}"
with_items: "{{ hello.results }}"

Answer 5

I think this construct works well enough for my needs.
- hosts: localhost
gather_facts: false
vars:
stuff: [ 0,2,4,6,8,10 ]
tasks:
- name: "Loop"
command: "echo {{ item }}"
with_items: "{{ stuff }}"
register: hello
- debug: "var=hello.results.{{item}}.stdout"
with_sequence: "0-{{stuff|length - 1}}"

Answer 6

I was looking at a similar problem and was confused by getting lots of output when I was expecting a relatively small msg or var from debug:. Turns out most of that output was the 'label' with which Ansible was prefixing each of those small outputs. It being a few years after this question was originally asked I've been using loop rather than with_items; this also has a label: option in loop_control:, so in my case for a similar problem - getting any /etc/passwd entries for users 'alice' or 'bob',
- hosts: all
gather_facts: false
serial: 1 # output easier to read when grouped by host
tasks:
- name: Look for users in /etc/passwd
command: grep {{ item }} /etc/passwd
register: res
ignore_errors: true
loop:
- alice
- bob
- debug:
msg: "{{ item.stdout_lines }}"
when: not item.failed
loop: "{{ res.results }}"
loop_control:
label: "{{ item.item }}"