added unsafe_writes as common file feature (#17016)

lib/ansible/module_utils/basic.py

@@ -254,6 +254,7 @@ FILE_COMMON_ARGUMENTS=dict(
     regexp = dict(), # used by assemble
     delimiter = dict(), # used by assemble
     directory_mode = dict(), # used by copy
+    unsafe_writes  = dict(type='bool'), # should be available to any module using atomic_move
 )
 
 PASSWD_ARG_RE = re.compile(r'^[-]{0,2}pass[-]?(word|wd)?')
@@ -902,7 +903,10 @@ class AnsibleModule(object):
                                          str(':'.join(new_context)))
             except OSError:
                 e = get_exception()
-                self.fail_json(path=path, msg='invalid selinux context: %s' % str(e), new_context=new_context, cur_context=cur_context, input_was=context)
+                if e.errno == 95: # skip certain errors are they are 'ok'.
+                    self.debug("Skipped setting selinux on '%s' as the operation is not suported: %s" % (path, to_str(e))
+                else:
+                    self.fail_json(path=path, msg='invalid selinux context: %s' % str(e), new_context=new_context, cur_context=cur_context, input_was=context)
             if rc != 0:
                 self.fail_json(path=path, msg='set selinux context failed')
             changed = True

lib/ansible/utils/module_docs_fragments/files.py

@@ -60,4 +60,14 @@ options:
       - level part of the SELinux file context. This is the MLS/MCS attribute,
         sometimes known as the C(range). C(_default) feature works as for
         I(seuser).
+  unsafe_writes:
+    description:
+      -  Normally this module uses atomic operations to prevent data corruption or inconsistent reads from the target files,
+         sometimes systems are configured or just broken in ways that prevent this. One example are docker mounted files,
+         they cannot be updated atomically and can only be done in an unsafe manner.
+      -  This boolean option allows ansible to fall back to unsafe methods of updating files for those cases in which you do
+         not have any other choice. Be aware that this is subject to race conditions and can lead to data corruption.
+    required: false
+    default: false
+    version_added: "2.2"
 """