StorCli text collector: fix pylint issues and handle StorCli not installed (#758)

* StorCli text collector: fix pylint issues and handle StorCli not installed

* StorCli text collector: Add HELP and TYPE strings.

text_collector_examples/storcli.py

 #!/usr/bin/env python
-# Script to parse StorCLI's JSON output and expose
-# MegaRAID health as Prometheus metrics.
-#
-# Tested against StorCLI 'Ver 1.14.12 Nov 25, 2014'.
-#
-# StorCLI reference manual:
-# http://docs.avagotech.com/docs/12352476
-#
-# Advanced Software Options (ASO) not exposed as metrics currently.
-#
-# JSON key abbreviations used by StorCLI are documented in the standard command
-# output, i.e.  when you omit the trailing 'J' from the command.
+"""
+Script to parse StorCLI's JSON output and expose
+MegaRAID health as Prometheus metrics.
+Tested against StorCLI 'Ver 1.14.12 Nov 25, 2014'.
+StorCLI reference manual:
+http://docs.avagotech.com/docs/12352476
+
+Advanced Software Options (ASO) not exposed as metrics currently.
+
+JSON key abbreviations used by StorCLI are documented in the standard command
+output, i.e.  when you omit the trailing 'J' from the command.
+"""
+
+from __future__ import print_function
 import argparse
 import json
+import os
 import subprocess
 DESCRIPTION = """Parses StorCLI's JSON output and exposes MegaRAID health as
     Prometheus metrics."""
 VERSION = '0.0.1'
-METRIC_PREFIX = 'megaraid_'
-METRIC_CONTROLLER_LABELS = '{{controller="{}", model="{}"}}'
-
 def main(args):
+    """ main """
+
+    # exporter variables
+    metric_prefix = 'megaraid_'
+    metric_controller_labels = '{{controller="{}", model="{}"}}'
+
     data = json.loads(get_storcli_json(args.storcli_path))
     # It appears that the data we need will always be present in the first
@@ -33,12 +39,14 @@ def main(args):
     status = data['Controllers'][0]
     metrics = {
-            'status_code': status['Command Status']['Status Code'],
-            'controllers': status['Response Data']['Number of Controllers'],
-            }
+        'status_code': status['Command Status']['Status Code'],
+        'controllers': status['Response Data']['Number of Controllers'],
+    }
     for name, value in metrics.iteritems():
-        print("{}{} {}".format(METRIC_PREFIX, name, value))
+        print('# HELP {}{} MegaRAID {}'.format(metric_prefix, name, name.replace('_', ' ')))
+        print('# TYPE {}{} gauge'.format(metric_prefix, name))
+        print("{}{} {}".format(metric_prefix, name, value))
     controller_info = []
     controller_metrics = {}
@@ -52,50 +60,69 @@ def main(args):
     for controller in overview:
         controller_index = controller['Ctl']
         model = controller['Model']
-        controller_info.append(METRIC_CONTROLLER_LABELS.format(controller_index, model))
+        controller_info.append(metric_controller_labels.format(controller_index, model))
         controller_metrics = {
-                # FIXME: Parse dimmer switch options
-                # 'dimmer_switch':          controller['DS'],
-
-                'battery_backup_healthy':   int(controller['BBU'] == 'Opt'),
-                'degraded':                 int(controller['Hlth'] == 'Dgd'),
-                'drive_groups':             controller['DGs'],
-                'emergency_hot_spare':      int(controller['EHS'] == 'Y'),
-                'failed':                   int(controller['Hlth'] == 'Fld'),
-                'healthy':                  int(controller['Hlth'] == 'Opt'),
-                'physical_drives':          controller['PDs'],
-                'ports':                    controller['Ports'],
-                'scheduled_patrol_read':    int(controller['sPR'] == 'On'),
-                'virtual_drives':           controller['VDs'],
-
-                # Reverse StorCLI's logic to make metrics consistent
-                'drive_groups_optimal':     int(controller['DNOpt'] == 0),
-                'virtual_drives_optimal':   int(controller['VNOpt'] == 0),
-                }
+            # FIXME: Parse dimmer switch options
+            # 'dimmer_switch':          controller['DS'],
+
+            'battery_backup_healthy':   int(controller['BBU'] == 'Opt'),
+            'degraded':                 int(controller['Hlth'] == 'Dgd'),
+            'drive_groups':             controller['DGs'],
+            'emergency_hot_spare':      int(controller['EHS'] == 'Y'),
+            'failed':                   int(controller['Hlth'] == 'Fld'),
+            'healthy':                  int(controller['Hlth'] == 'Opt'),
+            'physical_drives':          controller['PDs'],
+            'ports':                    controller['Ports'],
+            'scheduled_patrol_read':    int(controller['sPR'] == 'On'),
+            'virtual_drives':           controller['VDs'],
+
+            # Reverse StorCLI's logic to make metrics consistent
+            'drive_groups_optimal':     int(controller['DNOpt'] == 0),
+            'virtual_drives_optimal':   int(controller['VNOpt'] == 0),
+            }
     for name, value in controller_metrics.iteritems():
-        print('{}{}{{controller="{}"}} {}'.format(METRIC_PREFIX, name, controller_index, value))
-
+        print('# HELP {}{} MegaRAID {}'.format(metric_prefix, name, name.replace('_', ' ')))
+        print('# TYPE {}{} gauge'.format(metric_prefix, name))
+        print('{}{}{{controller="{}"}} {}'.format(metric_prefix, name,
+                                                  controller_index, value))
+
+    if controller_info:
+        print('# HELP {}{} MegaRAID controller info'.format(metric_prefix, 'controller_info'))
+        print('# TYPE {}{} gauge'.format(metric_prefix, name))
     for labels in controller_info:
-        print('{}{}{} {}'.format(METRIC_PREFIX, 'controller_info', labels, 1))
+        print('{}{}{} {}'.format(metric_prefix, 'controller_info', labels, 1))
 def get_storcli_json(storcli_path):
-    storcli_cmd = [storcli_path, 'show', 'all', 'J']
-    proc = subprocess.Popen(storcli_cmd, stdout=subprocess.PIPE,
-                            stderr=subprocess.PIPE)
-    return proc.communicate()[0]
+    """Get storcli output in JSON format."""
+
+    # Check if storcli is installed
+    if os.path.isfile(storcli_path) and os.access(storcli_path, os.X_OK):
+        storcli_cmd = [storcli_path, 'show', 'all', 'J']
+        proc = subprocess.Popen(storcli_cmd, shell=False,
+                                stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        output_json = proc.communicate()[0]
+    else:
+        # Create an empty dummy-JSON where storcli not installed.
+        dummy_json = {"Controllers":[{
+            "Command Status": {"Status Code": 0, "Status": "Success",
+                               "Description": "None"},
+            "Response Data": {"Number of Controllers": 0}}]}
+        output_json = json.dumps(dummy_json)
+
+    return output_json
 if __name__ == "__main__":
-    parser = argparse.ArgumentParser(description=DESCRIPTION,
-                                        formatter_class=argparse.ArgumentDefaultsHelpFormatter)
-    parser.add_argument('--storcli_path',
+    PARSER = argparse.ArgumentParser(description=DESCRIPTION,
+                                     formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+    PARSER.add_argument('--storcli_path',
                         default='/opt/MegaRAID/storcli/storcli64',
                         help='path to StorCLi binary')
-    parser.add_argument('--version',
+    PARSER.add_argument('--version',
                         action='version',
                         version='%(prog)s {}'.format(VERSION))
-    args = parser.parse_args()
-    main(args)
+    ARGS = PARSER.parse_args()
+    main(ARGS)