Adding module_utils to allow for common utilites that can be shared a…

…mong ansible modules. (#2623)

What is the motivation for this PR?
Sometimes, there are utilities that are required for across multiple ansible modules in ansible/library.

For example:
* creating of a timestamped debug file, and printing message to it.
* minigraph_facts has logic to get port_name_to_alias_map that is based on 'hwksu'. If we want to use the same logic in some other ansible module, then we would have to replicate the same code in both the modules.

How did you do it?
Usage of ansible module_utils is defined at https://docs.ansible.com/ansible/latest/dev_guide/developing_module_utilities.html
To have custom module_utils, we need to:
* Add module_utils directory under ansible.
* Add module_utils in ansible.cfg to point to this module_utils directory.

So, we did the following:
* Added module_utils directory under ansible
* Added module_utils in ansible.cfg to use this directory for ansible modules.

Added debug_utils as an example with the following methods/utilities:
* create_debug_file - create a timestamped debug file
* print_debug_msg - print a message to the debug file.

Added debug commands above to conn_graph_facts as an example.

How did you verify/test it?
Made sure that conn_graph_facts works and the debug file is created.

ansible/ansible.cfg

@@ -13,6 +13,7 @@
 
 inventory      = /etc/ansible/hosts
 library        = library:library/ixia
+module_utils   = module_utils
 remote_tmp     = $HOME/.ansible/tmp
 pattern        = *
 forks          = 5

ansible/library/conn_graph_facts.py

@@ -8,6 +8,7 @@
 from operator import itemgetter
 from itertools import groupby
 from collections import defaultdict
+from ansible.module_utils.debug_utils import create_debug_file, print_debug_msg
 
 DOCUMENTATION='''
 module: conn_graph_facts.py
@@ -270,10 +271,12 @@ def find_graph(hostnames):
 
     # Finding the graph file contains all duts from hostnames,
     for fn in file_list:
+        print_debug_msg(debug_fname, "Looking at conn graph file: %s for hosts %s" % (fn, hostnames))
         filename = os.path.join(LAB_GRAPHFILE_PATH, fn)
         lab_graph = Parse_Lab_Graph(filename)
         lab_graph.parse_graph()
         if lab_graph.contains_hosts(hostnames):
+            print_debug_msg(debug_fname, ("Returning lab graph from conn graph file: %s for hosts %s" % (fn, hostnames)))
             return lab_graph
 
     # Fallback to return an empty connection graph, this is
@@ -284,6 +287,8 @@ def find_graph(hostnames):
     lab_graph.parse_graph()
     return lab_graph
 
+debug_fname = None
+
 def main():
     module = AnsibleModule(
         argument_spec=dict(
@@ -297,6 +302,8 @@ def main():
         supports_check_mode=True
     )
     m_args = module.params
+    global debug_fname
+    debug_fname = create_debug_file("/tmp/conn_graph_debug.txt")
 
     hostnames = m_args['hosts']
     anchor = m_args['anchor']

ansible/module_utils/debug_utils.py

@@ -0,0 +1,25 @@
+import os
+from pprint import pprint
+from ansible.module_utils.basic import datetime
+
+
+def create_debug_file(debug_fname, add_timestamp=True):
+    curtime = datetime.datetime.now().isoformat()
+    if add_timestamp:
+        # Check if there is an extension
+        fname_split = os.path.splitext(debug_fname)
+        if fname_split[1] != '':
+            # We have an extension
+            timed_debug_fname = (fname_split[0] + ".%s" + fname_split[1]) % curtime
+        else:
+            timed_debug_fname = (fname_split[0] + ".%s") % curtime
+    else:
+        timed_debug_fname = debug_fname
+    if os.path.exists(timed_debug_fname) and os.path.isfile(timed_debug_fname):
+        os.remove(timed_debug_fname)
+    return timed_debug_fname
+
+
+def print_debug_msg(debug_fname, msg):
+    with open(debug_fname, 'a') as fp:
+        pprint(msg, fp)