Good day, all. I hope I’m not wearing out my welcome with too many questions.
In the following playbook, I first find any know_host file for any user on a particular system. I then copy a file with the list of additions to add to the known_hosts files. What I want to do is use the output of my register values to make changes to those know_host files, which my last play does. My iteration is wrong, though.
The playbook:
You want stdout_lines rather than stdout. The former is a list with new-lines removed. The latter is a possibly very long string with the complete output stream intact.
- name: Append to all known_host files
shell: cat /tmp/append >> {{ item }}
loop:
- '{{ known.stdout_lines }}'
Todd, I made the change, but, the last play failed:
TASK [Append to all known_host files] *****************************************************************************************************
Thursday 23 May 2024 11:06:33 -0400 (0:00:01.629) 0:00:06.012 **********
Thursday 23 May 2024 11:06:33 -0400 (0:00:01.629) 0:00:06.011 **********
failed: [myhost] (item=[‘/root/.ssh/known_hosts’, ‘/home/user1/.ssh/known_hosts’, ‘/home/user2/.ssh/known_hosts’, ‘/home/user3/.ssh/known_hosts’, ‘/home/user4/.ssh/known_hosts’]) => changed=true
ansible_loop_var: item
cmd: cat /tmp/append >> [‘/root/.ssh/known_hosts’, ‘/home/user1/.ssh/known_hosts’, ‘/home/user2/.ssh/known_hosts’, ‘/home/user3/.ssh/known_hosts’, ‘/home/user4/.ssh/known_hosts’]
delta: ‘0:00:00.012330’
end: ‘2024-05-23 11:06:33.947617’
item:
- /root/.ssh/known_hosts
- /home/user1/.ssh/known_hosts
- /home/user2/.ssh/known_hosts
- /home/user3/.ssh/known_hosts
- /home/user4/.ssh/known_hosts
msg: non-zero return code
rc: 1
start: ‘2024-05-23 11:06:33.935287’
stderr: ‘/bin/sh: line 1: [/root/.ssh/known_hosts,: No such file or directory’
stderr_lines:
stdout: ‘’
stdout_lines:
I wonder if [ in [/root/.ssh/known_hosts is getting in the way, since /root/.ssh/known_host does exist.
Gah! Of course. known.stdout_lines is a list, so
loop:
- '{{ known.stdout_lines }}'
passes the whole list as a single item. So you need to not put the list in a list:
loop: '{{ known.stdout_lines }}'
should do the trick.
Yupper, that worked. And, I appreciate the explanation. As the Farber College motto states, “Learning is Good”.
You want stdout_lines rather than stdout. The former is a list with new-lines removed. The latter is a possibly very long string with the complete output stream intact.
- name: Append to all known_host files shell: cat /tmp/append >> {{ item }} loop: - '{{ known.stdout_lines }}'
That should probably just loop over the list itself? So:
Very subtle but very different. Great catch Todd.
In the first instance you create a list that contains a single item – another list called known.stdout_lines.
loop:
In the second instance you provide a list called known.stdout_lines as the list for the loop:
loop: ‘{{ known.stdout_lines }}’
The second instance is the desired behavior. The difference is subtle at first glance but makes a world of difference in execution.
Walter
Here is an illustration of the difference for those interested.
hosts: localhost
gather_facts: false
become: false
vars:
my_list: [ one, two, three ]
tasks:
debug: var=item
loop:
‘{{ my_list }}’
name: construct 2
debug: var=item
loop: ‘{{ my_list }}’
% ansible-playbook -i localhost, loop.yml
PLAY [test loop constructs] ********************************************************************************************
TASK [construct 1] *****************************************************************************************************
ok: [localhost] => (item=[‘one’, ‘two’, ‘three’]) => {
“ansible_loop_var”: “item”,
“item”: [
“one”,
“two”,
“three”
]
}
TASK [construct 2] *****************************************************************************************************
ok: [localhost] => (item=one) => {
“ansible_loop_var”: “item”,
“item”: “one”
}
ok: [localhost] => (item=two) => {
“ansible_loop_var”: “item”,
“item”: “two”
}
ok: [localhost] => (item=three) => {
“ansible_loop_var”: “item”,
“item”: “three”
}
PLAY RECAP *************************************************************************************************************
localhost : ok=2 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
Walter