"Unable to retrieve file contents" trying to supply ansible playbook from stdin

Question

I wanted to supply a playbook to ansible-playbook 2.4.2.0 from stdin on RHEL 7.5, I found this post which seemed very promising but it's not working for me:

$ cat  ~/simple-ansible-playbook.yaml | ansible-playbook -i ~/inventory.yaml /dev/stdin
ERROR! Unable to retrieve file contents
Could not find or access '/dev/stdin'
$

I tracked down the message to /usr/lib/python2.7/site-packages/ansible/parsing/dataloader.py:

    if not self.path_exists(b_file_name) or not self.is_file(b_file_name):
        raise AnsibleFileNotFound("Unable to retrieve file contents", file_name=file_name)

os.path.isfile() returns False for /dev/stdin which is a symlink to a character special file:

$ ls -l /dev/stdin
lrwxrwxrwx. 1 root root 15 Nov 11 13:11 /dev/stdin -> /proc/self/fd/0
$ ls -Ll /dev/stdin
crw--w----. 1 stack tty 136, 3 Feb 15 07:45 /dev/stdin

Does anyone have any ideas how to get this to work? I don't understand why it seemed to work for the cited post but it's not working for me.

Update

I think I understand this better. The original post used a here document which the shell apparently returns into a regular file. In my method, the data is in a pipe. I didn't realize the shell behaved differently in this respect: I figured the here document would result in a pipe too. So at least I learned something new about the difference but apparently I can't do what I want unless ansible-playbook changes.

Answer 1

I figured I'm going to have the bite the bullet and put the playbook in a temporary regular file rather than feeding it through stdin.

Answer 2

The original post used a here document which the shell apparently returns into a regular file

The pipe version works fine on a modern version of ansible (I just used the heredoc to make the answer more succinct):

$ printf -- '- hosts: all\n  tasks:\n    - debug: msg=hello\n' | \
      ansible-playbook -c local -i localhost, /dev/stdin

PLAY [all] *********************************************************************

TASK [Gathering Facts] *********************************************************
ok: [localhost]

TASK [debug] *******************************************************************
ok: [localhost] =>
  msg: hello

PLAY RECAP *********************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=0

$ ls -l /dev/stdin
lrwxrwxrwx 1 root root 15 Feb 15 16:44 /dev/stdin -> /proc/self/fd/0

$ ansible --version
ansible 2.7.7
  config file = None
  configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/local/lib/python2.7/dist-packages/ansible
  executable location = /usr/local/bin/ansible
  python version = 2.7.15rc1 (default, Nov 12 2018, 14:31:15) [GCC 7.3.0]

So the solution to your problem is to upgrade to a modern version of ansible.

However, I didn't want to be all gloom and doom, so there is a work-around available to you, if you insist on feeding the data into ansible via a pipe: cheat and serialize the pipestream to a file with tee:

$ printf -- '- hosts: all\n  tasks:\n    - debug: msg=hello\n' | \
      tee being-on-old-software-is-dangerous.yml | \
      ansible-playbook -c local -i localhost, being-on-old-software-is-dangerous.yml