Implement ok of the Promotheus Exporter, need to add the plugin documentation

conf/glances.conf

@@ -361,6 +361,22 @@ port=5678
 # - Third frame with the Glances plugin stats (JSON)
 prefix=G
 
+[prometheus]
+# Configuration for the --export-prometheus option
+# https://prometheus.io
+# Create a Prometheus exporter listening on localhost:9091 (default configuration)
+# Metric are exporter using the following name:
+#   <prefix>_<plugin>_<stats> (all specials character are replaced by '_')
+# Note: You should add this exporter to your Prometheus server configuration:
+#   scrape_configs:
+#    - job_name: 'glances_exporter'
+#      scrape_interval: 5s
+#      static_configs:
+#        - targets: ['localhost:9091']
+host=localhost
+port=9091
+prefix=glances
+
 ##############################################################################
 # AMPS
 # * enable: Enable (true) or disable (false) the AMP

docs/gw/prometheus.rst

@@ -0,0 +1,34 @@
+.. _cassandra:
+
+Cassandra
+=========
+
+You can export statistics to a ``Cassandra`` or ``Scylla`` server.
+The connection should be defined in the Glances configuration file as
+following:
+
+.. code-block:: ini
+
+    [cassandra]
+    host=localhost
+    port=9042
+    protocol_version=3
+    keyspace=glances
+    replication_factor=2
+    table=localhost
+
+and run Glances with:
+
+.. code-block:: console
+
+    $ glances --export-cassandra
+
+The data model is the following:
+
+.. code-block:: ini
+
+    CREATE TABLE <table> (plugin text, time timeuuid, stat map<text,float>, PRIMARY KEY (plugin, time))
+
+Only numerical stats are stored in the Cassandra table. All the stats
+are converted to float. If a stat cannot be converted to float, it is
+not stored in the database.

glances/exports/glances_cassandra.py

@@ -25,6 +25,7 @@ from numbers import Number
 
 from glances.logger import logger
 from glances.exports.glances_export import GlancesExport
+from glances.compat import iteritems
 
 from cassandra.cluster import Cluster
 from cassandra.util import uuid_from_time

glances/exports/glances_prometheus.py

@@ -0,0 +1,89 @@
+# -*- coding: utf-8 -*-
+#
+# This file is part of Glances.
+#
+# Copyright (C) 2017 Nicolargo <nicolas@nicolargo.com>
+#
+# Glances is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Glances 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 Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+"""Prometheus interface class."""
+
+import sys
+from datetime import datetime
+from numbers import Number
+
+from glances.logger import logger
+from glances.exports.glances_export import GlancesExport
+from glances.compat import iteritems
+
+from prometheus_client import start_http_server, Gauge
+
+
+class Export(GlancesExport):
+
+    """This class manages the Prometheus export module."""
+
+    METRIC_SEPARATOR = '_'
+
+    def __init__(self, config=None, args=None):
+        """Init the Prometheus export IF."""
+        super(Export, self).__init__(config=config, args=args)
+
+        # Optionals configuration keys
+        self.prefix = 'glances'
+
+        # Load the Prometheus configuration file section
+        self.export_enable = self.load_conf('prometheus',
+                                            mandatories=['host', 'port'],
+                                            options=['prefix'])
+        if not self.export_enable:
+            sys.exit(2)
+
+        # Init the metric dict
+        # Perhaps a better method is possible...
+        self._metric_dict = {}
+
+        # Init the Prometheus Exporter
+        self.init()
+
+    def init(self):
+        """Init the Prometheus Exporter"""
+        try:
+            start_http_server(port=int(self.port), addr=self.host)
+        except Exception as e:
+            logger.critical("Can not start Prometheus exporter on {}:{} ({})".format(self.host, self.port, e))
+            sys.exit(2)
+        else:
+            logger.info("Start Prometheus exporter on {}:{}".format(self.host, self.port))
+
+    def export(self, name, columns, points):
+        """Write the points to the Prometheus exporter using Gauge."""
+        logger.debug("Export {} stats to Prometheus exporter".format(name))
+
+        # Remove non number stats and convert all to float (for Boolean)
+        data = {k: float(v) for (k, v) in iteritems(dict(zip(columns, points))) if isinstance(v, Number)}
+
+        # Write metrics to the Prometheus exporter
+        for k, v in iteritems(data):
+            # Prometheus metric name: prefix_<glances stats name>
+            metric_name = self.prefix + self.METRIC_SEPARATOR + name + self.METRIC_SEPARATOR + k
+            # Prometheus is very sensible to the metric name
+            # See: https://prometheus.io/docs/practices/naming/
+            for c in ['.', '-', '/', ' ']:
+                metric_name = metric_name.replace(c, self.METRIC_SEPARATOR)
+            # Manage an internal dict between metric name and Gauge
+            if metric_name not in self._metric_dict:
+                self._metric_dict[metric_name] = Gauge(metric_name, k)
+            # Write the value
+            self._metric_dict[metric_name].set(v)

glances/main.py

@@ -173,22 +173,24 @@ Examples of use:
                             dest='path_graph', help='set the export path for graphs (default is {})'.format(tempfile.gettempdir()))
         parser.add_argument('--export-csv', default=None,
                             dest='export_csv', help='export stats to a CSV file')
-        parser.add_argument('--export-influxdb', action='store_true', default=False,
-                            dest='export_influxdb', help='export stats to an InfluxDB server (influxdb lib needed)')
         parser.add_argument('--export-cassandra', action='store_true', default=False,
                             dest='export_cassandra', help='export stats to a Cassandra or Scylla server (cassandra lib needed)')
-        parser.add_argument('--export-opentsdb', action='store_true', default=False,
-                            dest='export_opentsdb', help='export stats to an OpenTSDB server (potsdb lib needed)')
-        parser.add_argument('--export-statsd', action='store_true', default=False,
-                            dest='export_statsd', help='export stats to a StatsD server (statsd lib needed)')
+        parser.add_argument('--export-couchdb', action='store_true', default=False,
+                            dest='export_couchdb', help='export stats to a CouchDB server (couch lib needed)')
         parser.add_argument('--export-elasticsearch', action='store_true', default=False,
                             dest='export_elasticsearch', help='export stats to an ElasticSearch server (elasticsearch lib needed)')
+        parser.add_argument('--export-influxdb', action='store_true', default=False,
+                            dest='export_influxdb', help='export stats to an InfluxDB server (influxdb lib needed)')
+        parser.add_argument('--export-opentsdb', action='store_true', default=False,
+                            dest='export_opentsdb', help='export stats to an OpenTSDB server (potsdb lib needed)')
+        parser.add_argument('--export-prometheus', action='store_true', default=False,
+                            dest='export_prometheus', help='export stats to a Prometheus exporter (prometheus_client lib needed)')
         parser.add_argument('--export-rabbitmq', action='store_true', default=False,
                             dest='export_rabbitmq', help='export stats to rabbitmq broker (pika lib needed)')
         parser.add_argument('--export-riemann', action='store_true', default=False,
                             dest='export_riemann', help='export stats to riemann broker (bernhard lib needed)')
-        parser.add_argument('--export-couchdb', action='store_true', default=False,
-                            dest='export_couchdb', help='export stats to a CouchDB server (couch lib needed)')
+        parser.add_argument('--export-statsd', action='store_true', default=False,
+                            dest='export_statsd', help='export stats to a StatsD server (statsd lib needed)')
         parser.add_argument('--export-zeromq', action='store_true', default=False,
                             dest='export_zeromq', help='export stats to a ZeroMQ server (pyzmq lib needed)')
         # Client/Server option

optional-requirements.txt

@@ -10,6 +10,7 @@ netifaces
 nvidia-ml-py; python_version == "2.7"
 pika
 potsdb
+prometheus_client
 py-cpuinfo
 pymdstat
 pysnmp

setup.py

@@ -85,7 +85,8 @@ setup(
         'chart': ['matplotlib'],
         'docker': ['docker>=2.0.0'],
         'export': ['bernhard', 'cassandra-driver', 'couchdb', 'elasticsearch',
-                   'influxdb>=1.0.0', 'pika', 'potsdb', 'pyzmq', 'statsd'],
+                   'influxdb>=1.0.0', 'pika', 'potsdb', 'prometheus_client',
+                   'pyzmq', 'statsd'],
         'folders:python_version<"3.5"': ['scandir'],
         'gpu:python_version=="2.7"': ['nvidia-ml-py'],
         'ip': ['netifaces'],