Add creates= and removes= to the script: action

lib/ansible/runner/action_plugins/script.py

@@ -16,6 +16,7 @@
 # along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
 
 import os
+import re
 import shlex
 
 import ansible.constants as C
@@ -38,12 +39,60 @@ class ActionModule(object):
             # in check mode, always skip this module
             return ReturnData(conn=conn, comm_ok=True, result=dict(skipped=True, msg='check mode not supported for this module'))
 
+        # extract ansible reserved parameters
+        # From library/command keep in sync
+        creates = None
+        removes = None
+        r = re.compile(r'(^|\s)(creates|removes)=(?P<quote>[\'"])?(.*?)(?(quote)(?<!\\)(?P=quote))((?<!\\)(?=\s)|$)')
+        for m in r.finditer(module_args):
+            v = m.group(4).replace("\\", "")
+            if m.group(2) == "creates":
+                creates = v
+            elif m.group(2) == "removes":
+                removes = v
+        module_args = r.sub("", module_args)
+
+
+        if creates:
+            # do not run the command if the line contains creates=filename
+            # and the filename already exists. This allows idempotence
+            # of command executions.
+            module_args_tmp = "path=%s" % creates
+            module_return = self.runner._execute_module(conn, tmp, 'stat', module_args_tmp, inject=inject, complex_args=complex_args, persist_files=True)
+            stat = module_return.result.get('stat', None)
+            if stat and stat.get('exists', False):
+                return ReturnData(
+                        conn=conn,
+                        comm_ok=True,
+                        result=dict(
+                                skipped=True,
+                                msg=("skipped, since %s exists" % creates)
+                            )
+                        )
+        if removes:
+            # do not run the command if the line contains removes=filename
+            # and the filename does not exist. This allows idempotence
+            # of command executions.
+            module_args_tmp = "path=%s" % removes
+            module_return = self.runner._execute_module(conn, tmp, 'stat', module_args_tmp, inject=inject, complex_args=complex_args, persist_files=True)
+            stat = module_return.result.get('stat', None)
+            if stat and not stat.get('exists', False):
+                return ReturnData(
+                        conn=conn,
+                        comm_ok=True,
+                        result=dict(
+                                skipped=True,
+                                msg=("skipped, since %s does not exist" % removes)
+                            )
+                        )
+
         # Decode the result of shlex.split() to UTF8 to get around a bug in that's been fixed in Python 2.7 but not Python 2.6.
         # See: http://bugs.python.org/issue6988
         tokens  = shlex.split(module_args.encode('utf8'))
         tokens = [s.decode('utf8') for s in tokens]
-
+        # extract source script
         source  = tokens[0]
+
         # FIXME: error handling
         args    = " ".join(tokens[1:])
         source  = template.template(self.runner.basedir, source, inject)

library/commands/script

@@ -18,6 +18,18 @@ options:
     required: true
     default: null
     aliases: []
+  creates:
+    description:
+      - a filename, when it already exists, this step will B(not) be run.
+    required: no
+    default: null
+    version_added: "1.5"
+  removes:
+    description:
+      - a filename, when it does not exist, this step will B(not) be run.
+    required: no
+    default: null
+    version_added: "1.5"
 notes:
   - It is usually preferable to write Ansible modules than pushing scripts. Convert your script to an Ansible module for bonus points!
 author: Michael DeHaan
@@ -26,4 +38,10 @@ author: Michael DeHaan
 EXAMPLES = '''
 # Example from Ansible Playbooks
 - script: /some/local/script.sh --some-arguments 1234
+
+# Run a script that creates a file, but only if the file is not yet created
+- script: /some/local/create_file.sh --some-arguments 1234 creates=/the/created/file.txt
+
+# Run a script that removes a file, but only if the file is not yet removed
+- script: /some/local/remove_file.sh --some-arguments 1234 removes=/the/removed/file.txt
 '''