Adding "follow" param for file/copy options

Also modifies the template action plugin to use this new param
when executing the file/copy modules for templating so that links
are preserved correctly.

Fixes #8998

lib/ansible/module_utils/basic.py

@@ -151,6 +151,7 @@ FILE_COMMON_ARGUMENTS=dict(
     serole = dict(),
     selevel = dict(),
     setype = dict(),
+    follow = dict(type='bool', default=False),
     # not taken by the file module, but other modules call file so it must ignore them.
     content = dict(no_log=True),
     backup = dict(),
@@ -295,6 +296,11 @@ class AnsibleModule(object):
         else:
             path = os.path.expanduser(path)
 
+        # if the path is a symlink, and we're following links, get
+        # the target of the link instead for testing
+        if params.get('follow', False) and os.path.islink(path):
+            path = os.path.realpath(path)
+
         mode   = params.get('mode', None)
         owner  = params.get('owner', None)
         group  = params.get('group', None)

lib/ansible/runner/action_plugins/template.py

@@ -33,9 +33,6 @@ class ActionModule(object):
     def run(self, conn, tmp, module_name, module_args, inject, complex_args=None, **kwargs):
         ''' handler for template operations '''
 
-        # note: since this module just calls the copy module, the --check mode support
-        # can be implemented entirely over there
-
         if not self.runner.is_playbook:
             raise errors.AnsibleError("in current versions of ansible, templates are only usable in playbooks")
 
@@ -121,6 +118,7 @@ class ActionModule(object):
                src=xfered,
                dest=dest,
                original_basename=os.path.basename(source),
+               follow=True,
             )
             module_args_tmp = utils.merge_module_args(module_args, new_module_args)
 
@@ -132,12 +130,18 @@ class ActionModule(object):
                     res.diff = dict(before=dest_contents, after=resultant)
                 return res
         else:
-            # if we're running in check mode, we still want the file module
-            # to execute, since we can't know if anything would be changed here,
-            # so we inject the check mode param into the module args and rely on
-            # the file module to report its changed status
+            # when running the file module based on the template data, we do
+            # not want the source filename (the name of the template) to be used,
+            # since this would mess up links, so we clear the src param and tell
+            # the module to follow links
+            new_module_args = dict(
+                src=None,
+                follow=True,
+            )
+            # be sure to inject the check mode param into the module args and
+            # rely on the file module to report its changed status
             if self.runner.noop_on_check(inject):
-                new_module_args = dict(CHECKMODE=True)
-                module_args = utils.merge_module_args(module_args, new_module_args)
+                new_module_args['CHECKMODE'] = True
+            module_args = utils.merge_module_args(module_args, new_module_args)
             return self.runner._execute_module(conn, tmp, 'file', module_args, inject=inject, complex_args=complex_args)
 

lib/ansible/utils/module_docs_fragments/files.py

@@ -67,4 +67,12 @@ 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).
+  follow:
+    required: false
+    default: "no"
+    choices: [ "yes", "no" ]
+    version_added: "1.8"
+    description:
+      - 'This flag indicates that filesystem links, if they exist, should be followed.'
+
 """