setup: more reliably detect container environment (#66183)

* virtual facts: /proc/<pid>/environ is NULL-separated
* non-empty "container" env is a guest container
* This is consistent with `systemd-detect-virt --container`
* fact utils: line_sep option: specify delim for split
* allow using the same function to split null-delimited objects

changelogs/fragments/detect-generic-container.yml

@@ -0,0 +1,4 @@
+---
+bugfixes:
+- virtual facts - detect generic container environment based on non-empty
+  "container" env var

lib/ansible/module_utils/facts/utils.py

@@ -36,11 +36,17 @@ def get_file_content(path, default=None, strip=True):
     return data
 
 
-def get_file_lines(path, strip=True):
+def get_file_lines(path, strip=True, line_sep=None):
     '''get list of lines from file'''
     data = get_file_content(path, strip=strip)
     if data:
-        ret = data.splitlines()
+        if line_sep is None:
+            ret = data.splitlines()
+        else:
+            if len(line_sep) == 1:
+                ret = data.rstrip(line_sep).split(line_sep)
+            else:
+                ret = data.split(line_sep)
     else:
         ret = []
     return ret

lib/ansible/module_utils/facts/virtual/linux.py

@@ -49,7 +49,7 @@ class LinuxVirtual(Virtual):
 
         # lxc does not always appear in cgroups anymore but sets 'container=lxc' environment var, requires root privs
         if os.path.exists('/proc/1/environ'):
-            for line in get_file_lines('/proc/1/environ'):
+            for line in get_file_lines('/proc/1/environ', line_sep='\x00'):
                 if re.search('container=lxc', line):
                     virtual_facts['virtualization_type'] = 'lxc'
                     virtual_facts['virtualization_role'] = 'guest'
@@ -58,6 +58,10 @@ class LinuxVirtual(Virtual):
                     virtual_facts['virtualization_type'] = 'podman'
                     virtual_facts['virtualization_role'] = 'guest'
                     return virtual_facts
+                if re.search('^container=.', line):
+                    virtual_facts['virtualization_type'] = 'container'
+                    virtual_facts['virtualization_role'] = 'guest'
+                    return virtual_facts
 
         if os.path.exists('/proc/vz') and not os.path.exists('/proc/lve'):
             virtual_facts['virtualization_type'] = 'openvz'