Ansible wrongly reports 'command not found' error - ansible

Question

I am new to Ansible and I cannot solve an error: I use the ansible.builtin.shell to call the pcs utility (Pacemaker). The pcs is installed on the remote machine, and I can use it when I ssh that machine, but Ansible reports a 'command not found' error with error code 127.
Here is my inventory.yml:
---
all:
children:
centos7:
hosts:
UVMEL7:
ansible_host: UVMEL7
Here is my play-book, TestPcs.yaml:
---
- name: Test the execution of pcs command
hosts: UVMEL7
tasks:
- name: Call echo
ansible.builtin.shell: echo
- name: pcs
ansible.builtin.shell: pcs
Note: I also used the echo command to verify that I am corectly using ansible.builtin.shell.
I launch my play-book with: ansible-playbook -i inventory.yml TestPcs.yaml --user=traite
And I get this result:
PLAY [Test the execution of pcs command] *****************************************************************************************************************************************************************************************************
TASK [Gathering Facts] ***********************************************************************************************************************************************************************************************************************
ok: [UVMEL7]
TASK [Call echo] *****************************************************************************************************************************************************************************************************************************
changed: [UVMEL7]
TASK [pcs] ***********************************************************************************************************************************************************************************************************************************
fatal: [UVMEL7]: FAILED! => {"changed": true, "cmd": "pcs", "delta": "0:00:00.003490", "end": "2022-03-10 15:02:17.418475", "msg": "non-zero return code", "rc": 127, "start": "2022-03-10 15:02:17.414985", "stderr": "/bin/sh: pcs : commande introuvable", "stderr_lines": ["/bin/sh: pcs : commande introuvable"], "stdout": "", "stdout_lines": []}
PLAY RECAP ***********************************************************************************************************************************************************************************************************************************
UVMEL7 : ok=2 changed=1 unreachable=0 failed=1 skipped=0 rescued=0 ignored=0
The pcs command is failing and in stderr, there is a 'command not found' error.
On the other and, when I ssh the machine and run pcs command, the command is executed and returns 1 which is different from 127. It is normal that pcs returns an error: I simplified the test case to the strict minimum to keep my question short.
I expect Ansible to have the same behavior: Error on pcs with return code 1.

Answer 1

Here is what I did to simulate what Ansible does (Based on remarks by #Zeitounator): ssh <user>#<machine> '/bin/bash -c "echo $PATH"'
I get my default PATH as explained in the manual page of bash. In my system sh links to bash.
I see that /etc/profile does the path manipulation that I need. However, it seems that because of the option -c, the bash is not started as login shell and therefore etc/profile is not sourced.
I end up doing the job manually:
---
- name: Test the execution of pcs command
hosts: UVMEL7
tasks:
- name: Call echo
ansible.builtin.shell: echo
- name: pcs
ansible.builtin.shell: source /etc/profile && pcs
Which executes pcs as expected.
To sum up, my executable was not executed because the folder holding it was not listed in my PATH environment variable. This was due to the fact that /bin/sh aka /bin/bash was called with the flag -c which prevents sourcing /etc/profile and other configuration files. The issue was 'solved' by sourcing manually the configuration file that correctly sets the PATH environment variable.