Added code to allow insertion of boilerplate into modules to make them able to share lots of code, the result

should be a huge reduction of total ansible source, at a slight cost of difficulty in original module development.

We need to apply this now to all modules, but may need to have some exemptions to things like command, which should
subclass this module.

hacking/test-module

@@ -31,6 +31,7 @@ import os
 import subprocess
 import traceback
 from ansible import utils
+from ansible import module_common
 
 try:
     import json
@@ -54,6 +55,23 @@ argsfile = open(argspath, 'w')
 argsfile.write(args)
 argsfile.close()
 
+module_fh = open(modfile)
+module_data = module_fh.read()
+included_boilerplate = module_data.find(module_common.REPLACER) != -1
+module_fh.close()
+
+if included_boilerplate:
+    module_data = module_data.replace(module_common.REPLACER, module_common.MODULE_COMMON)
+    modfile2_path = os.path.expanduser("~/.ansible_module_generated")
+    print "* including generated source, if any, saving to: %s" % modfile2_path
+    print "* this will offset any line numbers in tracebacks!"
+    modfile2 = open(modfile2_path, 'w')
+    modfile2.write(module_data)
+    modfile2.close()
+    modfile = modfile2_path
+else:
+    print "* module boilerplate substitution not requested in module, tracebacks will be unaltered"
+
 os.system("chmod +x %s" % modfile)
 cmd = subprocess.Popen("%s %s" % (modfile, argspath), 
     shell=True,

lib/ansible/module_common.py

@@ -0,0 +1,114 @@
+# (c) 2012, Michael DeHaan <michael.dehaan@gmail.com>
+#
+# This file is part of Ansible
+#
+# Ansible is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Ansible is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
+
+REPLACER = "#<<INCLUDE_ANSIBLE_MODULE_COMMON>>"
+
+MODULE_COMMON = """
+
+# == BEGIN DYNAMICALLY INSERTED CODE ==
+
+# ansible modules can be written in any language.  To simplify
+# development of Python modules, the functions available here
+# can be inserted in any module source automatically by including
+# #<<INCLUDE_ANSIBLE_MODULE_COMMON>> on a blank line by itself inside
+# of an ansible module. The source of this common code lives
+# in lib/ansible/module_common.py
+
+try:
+    import json
+except ImportError:
+    import simplejson as json
+import os
+import shlex
+import subprocess
+import sys
+import syslog
+
+class AnsibleModule(object):
+
+    def __init__(self, argument_spec, bypass_checks=False, no_log=False):
+        ''' 
+        @argument_spec: a hash of argument names, where the values are none if
+        the types are NOT checked, or a list of valid types where the argument
+        must be one of those values.  All possible arguments must be listed.
+
+        @required_arguments: a list of arguments that must be sent to the module
+        '''
+
+        self.argument_spec = argument_spec
+        (self.params, self.args) = self._load_params()
+        if not bypass_checks:
+            self._check_required_arguments()
+            self._check_argument_types()
+        if not no_log:
+            self._log_invocation()
+
+    def _check_required_arguments(self):
+        ''' ensure all required arguments are present '''
+        missing = []
+        for (k,v) in self.argument_spec.iteritems():
+            (type_spec, required) = v
+            if required and k not in self.params:
+                missing.append(k)
+        if len(missing) > 0:
+            self.fail_json(msg="missing required arguments: %s" % ",".join(missing))
+
+    def _check_argument_types(self):
+        ''' ensure all arguments have the requested values, and there are no stray arguments '''
+        for (k,v) in self.argument_spec.iteritems():
+            (type_spec, required) = v
+            if type_spec is not None:
+                if type(spec) == list:
+                    if v not in spec:
+                        self.fail_json(msg="value of %s must be one of: %s, recieved: %s" % (k, ",".join(spec), v))
+                else:
+                    self.fail_json(msg="internal error: do not know how to interpret argument_spec")
+
+    def _load_params(self):
+        ''' read the input and return a dictionary and the arguments string '''
+        if len(sys.argv) == 2 and os.path.exists(sys.argv[1]):
+            argfile = sys.argv[1]
+            args    = open(argfile, 'r').read()
+        else:
+            args = ' '.join(sys.argv[1:])
+        items   = shlex.split(args)
+        params = {}
+        for x in items:
+            (k, v) = x.split("=")
+            params[k] = v
+        return (params, args)        
+
+    def _log_invocation(self):
+        ''' log that ansible ran the module '''
+        syslog.openlog('ansible-%s' % os.path.basename(__file__))
+        syslog.syslog(syslog.LOG_NOTICE, 'Invoked with %s' % self.args)
+
+    def exit_json(self, rc=0, **kwargs):
+        ''' return from the module, without error '''
+        kwargs['rc'] = rc
+        print json.dumps(kwargs)
+        sys.exit(rc)
+
+    def fail_json(self, **kwargs):
+        ''' return from the module, with an error message '''
+        assert 'msg' in kwargs, "implementation error -- msg to explain the error is required"
+        kwargs['failed'] = True
+        self.exit_json(rc=1, **kwargs)
+
+# == END DYNAMICALLY INSERTED CODE ===
+
+"""

lib/ansible/runner/__init__.py

@@ -36,6 +36,7 @@ import ansible.constants as C
 import ansible.inventory
 from ansible import utils
 from ansible import errors
+from ansible import module_common
 import poller
 import connection
 from ansible import callbacks as ans_callbacks
@@ -721,16 +722,20 @@ class Runner(object):
 
         # use the correct python interpreter for the host
         host_variables = self.inventory.get_variables(conn.host)
+
+        module_data = ""
+        with open(in_path) as f:
+            module_data = f.read()
+            module_data = module_data.replace(module_common.REPLACER, module_common.MODULE_COMMON)
+          
         if 'ansible_python_interpreter' in host_variables:
             interpreter = host_variables['ansible_python_interpreter']
-            with open(in_path) as f:
-                module_lines = f.readlines()
+            module_lines = module_data.split('\n')
             if '#!' and 'python' in module_lines[0]:
                 module_lines[0] = "#!%s" % interpreter
-            self._transfer_str(conn, tmp, module, '\n'.join(module_lines))
-        else:
-            conn.put_file(in_path, out_path)
+            module_data = "\n".join(module_lines)
 
+        self._transfer_str(conn, tmp, module, module_data)
         return out_path
 
     # *****************************************************

library/slurp

@@ -17,60 +17,24 @@
 # You should have received a copy of the GNU General Public License
 # along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
 
-import sys
-import os
-import shlex
 import base64
-import syslog
 
-try:
-   import json
-except ImportError:
-   import simplejson as json
+# this is magic, see lib/ansible/module_common.py
+#<<INCLUDE_ANSIBLE_MODULE_COMMON>>
 
-# ===========================================
-# convert arguments of form a=b c=d
-# to a dictionary
+module = AnsibleModule(
+    argument_spec = dict(
+        src=(None,True),
+    )
+)
+source = module.params['src']
 
-if len(sys.argv) == 1:
-    sys.exit(1)
-argfile = sys.argv[1]
-if not os.path.exists(argfile):
-    sys.exit(1)
-
-args = open(argfile, 'r').read()
-items = shlex.split(args)
-syslog.openlog('ansible-%s' % os.path.basename(__file__))
-syslog.syslog(syslog.LOG_NOTICE, 'Invoked with %s' % args)
-
-params = {}
-for x in items:
-    (k, v) = x.split("=")
-    params[k] = v
-source  = os.path.expanduser(params['src'])
-
-# ==========================================
- 
-# raise an error if there is no template metadata
 if not os.path.exists(source):
-    print json.dumps(dict(
-        failed = 1,
-        msg    = "file not found: %s" % source
-    ))
-    sys.exit(1)
-
+    module.fail_json(msg="file not found: %s" % source)
 if not os.access(source, os.R_OK):
-    print json.dumps(dict(
-        failed = 1,
-        msg    = "file is not readable: %s" % source
-    ))
-    sys.exit(1)
+    module.fail_json(msg="file is not readable: %s" % source)
 
-# ==========================================
+data = base64.b64encode(file(source).read())
 
-data = file(source).read()
-data = base64.b64encode(data)
-
-print json.dumps(dict(content=data, encoding='base64'))
-sys.exit(0)
+module.exit_json(content=data, encoding='base64')