docker not detected in centos, alpine, debian

[cambid]

Summary

The facts for ansible_virtualization_type and ansible_virtualization_role are wrong if run in a dockercontainer of centos (tested with 8), alpine or debian (tested with buster). Only in an ubuntu-container (tested with focal or hirsute) are the values correct.
The problem can be reproduced with the latest stable version and the devel branch.

Issue Type

Bug Report

Component Name

setup, virtual/linux.py

Ansible Version

$ ansible --version
ansible 2.10.8
  config file = /etc/ansible/ansible.cfg
  configured module search path = ['/home/jfader/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3.9/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 3.9.3 (default, Apr  8 2021, 23:35:02) [GCC 10.2.0]

Configuration

$ ansible-config dump --only-changed

no changes recorded

OS / Environment

Archlinux

Steps to Reproduce

Start up two containers. One with centos:8 and one with ubuntu:hirsute:

docker run --name centos_8 -it centos:8 /bin/bash
dnf -y install python3

docker run --name ubuntu_hirsute -it ubuntu:hirsute /bin/bash
apt-get update && apt-get install -y python3

Inventory:

ubuntu_hirsute ansible_connection=docker
centos_8 ansible_connection=docker

Playbook:

---
- hosts: centos_8,ubuntu_hirsute
  gather_facts: True
  tasks:

    - name: "output information about virtualization (type and role)"
      debug:
        var: "{{ item }}"
      loop:
        - ansible_virtualization_type
        - ansible_virtualization_role

Expected Results

TASK [output information about virtualization (type and role)] ************************************************
ok: [centos_8] => (item=ansible_virtualization_type) => {
    "ansible_loop_var": "item",
    "ansible_virtualization_type": "docker",
    "item": "ansible_virtualization_type"
}
ok: [ubuntu_hirsute] => (item=ansible_virtualization_type) => {
    "ansible_loop_var": "item",
    "ansible_virtualization_type": "docker",
    "item": "ansible_virtualization_type"
}
ok: [centos_8] => (item=ansible_virtualization_role) => {
    "ansible_loop_var": "item",
    "ansible_virtualization_role": "guest",
    "item": "ansible_virtualization_role"
}
ok: [ubuntu_hirsute] => (item=ansible_virtualization_role) => {
    "ansible_loop_var": "item",
    "ansible_virtualization_role": "guest",
    "item": "ansible_virtualization_role"
}

Actual Results

TASK [output information about virtualization (type and role)] ************************************************
ok: [centos_8] => (item=ansible_virtualization_type) => {
    "ansible_loop_var": "item",
    "ansible_virtualization_type": "NA",
    "item": "ansible_virtualization_type"
}
ok: [ubuntu_hirsute] => (item=ansible_virtualization_type) => {
    "ansible_loop_var": "item",
    "ansible_virtualization_type": "docker",
    "item": "ansible_virtualization_type"
}
ok: [centos_8] => (item=ansible_virtualization_role) => {
    "ansible_loop_var": "item",
    "ansible_virtualization_role": "NA",
    "item": "ansible_virtualization_role"
}
ok: [ubuntu_hirsute] => (item=ansible_virtualization_role) => {
    "ansible_loop_var": "item",
    "ansible_virtualization_role": "guest",
    "item": "ansible_virtualization_role"
}

Code of Conduct

• I agree to follow the Ansible Code of Conduct

[ansibot]

Files identified in the description:

• lib/ansible/modules/setup.py

If these files are incorrect, please update the component name section of the description or use the !component bot command.

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[ansibot]

Files identified in the description:

• lib/ansible/module_utils/facts/virtual/linux.py
• lib/ansible/modules/setup.py

If these files are incorrect, please update the component name section of the description or use the !component bot command.

click here for bot help

[cambid]

Found the problem with the help of the ansible-IRC-channel and will create a PR for the problem.
The newest virt-what 1.21 uses a check for /.dockerenv and /.dockerinit: http://git.annexia.org/?p=virt-what.git;a=commitdiff;h=e2c49cda221f95cb65b1b3ac3ae15aa41d92f519