Refactored a few things to be more inline with the Ansible way. Passing testing.

library/system/at

@@ -25,13 +25,8 @@ short_description: Schedule the execution of a command or scripts via the at com
 description:
  - Use this module to schedule a command or script to run once in the future.
  - All jobs are executed in the a queue.
-version_added: "0.0"
+version_added: "1.5"
 options:
-  user:
-    description:
-     - The user to execute the at command as.
-    required: false
-    default: null
   command:
     description:
      - A command to be executed in the future.
@@ -42,22 +37,26 @@ options:
      - An existing script to be executed in the future.
     required: false
     default: null
-  unit_count:
+  count:
     description:
      - The count of units in the future to execute the command or script.
     required: true
-  unit_type:
+  units:
     description:
      - The type of units in the future to execute the command or script.
     required: true
     choices: ["minutes", "hours", "days", "weeks"]
-  action:
+  state:
     description:
-     - The action to take for the job defaulting to add. Unique will verify that there is only one entry in the queue.
+     - The state dictates if the command or script_file should be evaluated as present(added) or absent(deleted).
-     - Delete will remove all existing queued jobs.
+    required: false
-    required: true
+    choices: ["present", "absent"]
-    choices: ["add", "delete", "unique"]
+    default: "present"
-    default: add
+  unique:
+    description:
+     - If a matching job is present a new job will not be added.
+     required: false
+     default: false
 requirements:
  - at
 author: Richard Isaacson
@@ -65,33 +64,41 @@ author: Richard Isaacson
 
 EXAMPLES = '''
 # Schedule a command to execute in 20 minutes as root.
-- at: command="ls -d / > /dev/null" unit_count=20 unit_type="minutes"
+- at: command="ls -d / > /dev/null" count=20 units="minutes"
-
-# Schedule a script to execute in 1 hour as the neo user.
-- at: script_file="/some/script.sh" user="neo" unit_count=1 unit_type="hours"
 
 # Match a command to an existing job and delete the job.
-- at: command="ls -d / > /dev/null" action="delete"
+- at: command="ls -d / > /dev/null" state="absent"
 
 # Schedule a command to execute in 20 minutes making sure it is unique in the queue.
-- at: command="ls -d / > /dev/null" action="unique" unit_count=20 unit_type="minutes"
+- at: command="ls -d / > /dev/null" unique=true count=20 units="minutes"
 '''
 
 import os
 import tempfile
+def add_job(module, result, at_cmd, count, units, command, script_file):
+    at_command = "%s now + %s %s -f %s" % (at_cmd, count, units, script_file)
+    rc, out, err = module.run_command(at_command, check_rc=True)
+    if command:
+        os.unlink(script_file)
+    result['changed'] = True
 
-def matching_jobs(module, at_cmd, script_file, user=None):
+def delete_job(module, result, at_cmd, command, script_file):
+    for matching_job in matching_jobs(module, at_cmd, script_file):
+        at_command = "%s -d %s" % (at_cmd, matching_job)
+        rc, out, err = module.run_command(at_command, check_rc=True)
+        result['changed'] = True
+    if command:
+        os.unlink(script_file)
+    module.exit_json(**result)
+
+def matching_jobs(module, at_cmd, script_file):
     matching_jobs = []
 
     atq_cmd = module.get_bin_path('atq', True)
 
     # Get list of job numbers for the user.
     atq_command = "%s" % (atq_cmd)
-    if user:
+    rc, out, err = module.run_command(atq_command, check_rc=True)
-        atq_command = "su '%s' -c '%s'" % (user, atq_command)
-    rc, out, err = module.run_command(atq_command)
-    if rc != 0:
-        module.fail_json(msg=err)
     current_jobs = out.splitlines()
     if len(current_jobs) == 0:
         return matching_jobs
@@ -104,100 +111,85 @@ def matching_jobs(module, at_cmd, script_file, user=None):
     for current_job in current_jobs:
         split_current_job = current_job.split()
         at_command = "%s -c %s" % (at_cmd, split_current_job[0])
-        if user:
+        rc, out, err = module.run_command(at_command, check_rc=True)
-            at_command = "su '%s' -c '%s'" % (user, at_command)
-        rc, out, err = module.run_command(at_command)
-        if rc != 0:
-            module.fail_json(msg=err)
         if script_file_string in out:
             matching_jobs.append(split_current_job[0])
 
     # Return the list.
     return matching_jobs
 
+def create_tempfile(command):
+    filed, script_file = tempfile.mkstemp(prefix='at')
+    fileh = os.fdopen(filed, 'w')
+    fileh.write(command)
+    fileh.close()
+    return script_file
+
 #================================================
 
 def main():
 
     module = AnsibleModule(
         argument_spec = dict(
-            user=dict(required=False),
+            command=dict(required=False,
-            command=dict(required=False),
+                      type='str'),
-            script_file=dict(required=False),
+            script_file=dict(required=False,
-            unit_count=dict(required=False,
+                      type='str'),
+            count=dict(required=False,
                             type='int'),
-            unit_type=dict(required=False,
+            units=dict(required=False,
                            default=None,
-                           choices=["minutes", "hours", "days", "weeks"],
+                           choices=['minutes', 'hours', 'days', 'weeks'],
-                           type="str"),
+                           type='str'),
-            action=dict(required=False,
+            state=dict(required=False,
-                        default="add",
+                        default='present',
-                        choices=["add", "delete", "unique"],
+                        choices=['present', 'absent'],
-                        type="str")
+                        type='str'),
+            unique=dict(required=False,
+                        default=False,
+                        type='bool')
         ),
-        supports_check_mode = False,
+        mutually_exclusive = [['command', 'script_file']],
+        required_one_of = [['command', 'script_file']],
+        supports_check_mode = False
     )
 
     at_cmd = module.get_bin_path('at', True)
 
-    user           = module.params['user']
     command        = module.params['command']
     script_file    = module.params['script_file']
-    unit_count     = module.params['unit_count']
+    count          = module.params['count']
-    unit_type      = module.params['unit_type']
+    units          = module.params['units']
-    action         = module.params['action']
+    state          = module.params['state']
+    unique         = module.params['unique']
 
-    if ((action == 'add') and (not unit_count or not unit_type)):
+    if ((state == 'present') and (not count or not units)):
-        module.fail_json(msg="add action requires unit_count and unit_type")
+        module.fail_json(msg="present state requires count and units")
-
-    if (not command) and (not script_file):
-        module.fail_json(msg="command or script_file not specified")
-
-    if command and script_file:
-        module.fail_json(msg="command and script_file are mutually exclusive")
 
     result = {}
-    result['action'] = action
+    result['state'] = state
     result['changed'] = False
 
     # If command transform it into a script_file
     if command:
-        filed, script_file = tempfile.mkstemp(prefix='at')
+        script_file = create_tempfile(command)
-        fileh = os.fdopen(filed, 'w')
-        fileh.write(command)
-        fileh.close()
 
-    # if delete then return
+    # if absent remove existing and return
-    if action == 'delete':
+    if state == 'absent':
-        for matching_job in matching_jobs(module, at_cmd, script_file, user):
+        delete_job(module, result, at_cmd, command, script_file)
-            at_command = "%s -d %s" % (at_cmd, matching_job)
-            if user:
-                at_command = "su '%s' -c '%s'" % (user, at_ccommand)
-            rc, out, err = module.run_command(at_command)
-            if rc != 0:
-                module.fail_json(msg=err)
-            result['changed'] = True
-        module.exit_json(**result)
 
     # if unique if existing return unchanged
-    if action == 'unique':
+    if unique:
-        if len(matching_jobs(module, at_cmd, script_file, user)) != 0:
+        if len(matching_jobs(module, at_cmd, script_file)) != 0:
+            if command:
+                os.unlink(script_file)
             module.exit_json(**result)
 
     result['script_file'] = script_file
-    result['unit_count'] = unit_count
+    result['count'] = count
-    result['unit_type'] = unit_type
+    result['units'] = units
 
-    at_command = "%s now + %s %s -f %s" % (at_cmd, unit_count, unit_type, script_file)
+    add_job(module, result, at_cmd, count, units, command, script_file)
-    if user:
-        # We expect that if this is an installed the permissions are already correct for the user to execute it.
-        at_command = "su '%s' -c '%s'" % (user, at_command)
-    rc, out, err = module.run_command(at_command)
-    if rc != 0:
-        module.fail_json(msg=err)
-    if command:
-        os.unlink(script_file)
-    result['changed'] = True
 
     module.exit_json(**result)