title: Ansible get variable with dots in key
body: <p>I want Ansible to read out if user namespaces in the kernel are activated (CentOS).
  The respective value is visible when I run</p>
  
  <pre><code>- debug:
      msg: "{{ ansible_cmdline }}"
  </code></pre>
  
  <p>which gives me the output:</p>
  
  <pre><code> "msg": {
      "BOOT_IMAGE": "/vmlinuz-...",
      "LANG": "...",
      "crashkernel": "...",
      "namespace.unpriv_enable": "...",
      "quiet": ...,
      "rd.lvm.lv": "...",
      "rhgb": ...,
      "ro": ...,
      "root": "...",
      "user_namespace.enable": "1"
  }
  </code></pre>
  
  <p>However, I had no success to directly query the subkey:</p>
  
  <pre><code>- debug:
      msg: "{{ ansible_cmdline.user_namespace.enable }}"
  </code></pre>
  
  <p>Ansible interprets the <code>.enable</code> as a further subkey:
  <code>The task includes an option with an undefined variable. The error was: 'dict object' has no attribute 'user_namespace'</code></p>
  
  <p>How can I access the key <code>"user_namespace.enable"</code>?</p>