use global metric registry

README.md

@@ -71,6 +71,7 @@ default:
     fetch_custom_attributes: True
     fetch_tags: True
     fetch_alarms: True
+    #exporter_metrics: True
     collect_only:
         vms: True
         vmguests: True
@@ -113,6 +114,14 @@ limited:
 ```
 Switching sections can be done by adding ?section=limited to the URL.
 
+#### Montitoring the exporter metrics
+
+The exporter exposes metrics about its own behavior as [recommended](https://prometheus.io/docs/instrumenting/writing_clientlibs/#exposition) by Prometheus.
+
+Those metrics are available in the `/metrics` page. By default, those metrics are only exposed in the 'default' section (no need to collect it multiple times). This behavior can be controlled using the `VSPHERE_EXPORTER_METRICS` variable or using `exporter_metrics` in the configuration file.
+
+The metrics about the vmware_exporter process are only available on Linux (see [prometheus/client_python](https://github.com/prometheus/client_python#process-collector)).
+
 #### Environment Variables
 | Variable                      	| Precedence             | Defaults | Description                                      				|
 | --------------------------------------| ---------------------- | -------- | --------------------------------------------------------------------------|
@@ -124,6 +133,7 @@ Switching sections can be done by adding ?section=limited to the URL.
 | `VSPHERE_FETCH_CUSTOM_ATTRIBUTES`    	| config, env            | False    | Set to true to collect objects custom attributes as metric labels 	|
 | `VSPHERE_FETCH_TAGS`    		| config, env            | False    | Set to true to collect objects tags as metric labels 			|
 | `VSPHERE_FETCH_ALARMS`       		| config, env            | False    | Fetch objects triggered alarms, and in case of hosts hdw alarms as well 	|
+| `VSPHERE_EXPORTER_METRICS`   		| config, env            | True     | Set fo false to disable exposing the exporter metric in section default	|
 | `VSPHERE_COLLECT_HOSTS`      		| config, env            | True     | Set to false to disable collection of host metrics 			|
 | `VSPHERE_COLLECT_DATASTORES` 		| config, env            | True     | Set to false to disable collection of datastore metrics 			|
 | `VSPHERE_COLLECT_VMS`        		| config, env            | True     | Set to false to disable collection of virtual machine metrics 		|
@@ -142,6 +152,7 @@ You can create new sections as well, with very similiar variables. For example,
 | `VSPHERE_LIMITED_FETCH_CUSTOM_ATTRIBUTES`   	| config, env            | False    | Set to true to collect objects custom attributes as metric labels 	|
 | `VSPHERE_LIMITED_FETCH_TAGS`    		| config, env            | False    | Set to true to collect objects tags as metric labels 			|
 | `VSPHERE_LIMITED_FETCH_ALARMS`       		| config, env            | False    | Fetch objects triggered alarms, and in case of hosts hdw alarms as well	|
+| `VSPHERE_LIMITED_EXPORTER_METRICS`   		| config, env            | *        | Expose exporter metrics ( * Enabled only in section 'default' by default)	|
 | `VSPHERE_LIMITED_COLLECT_HOSTS`      		| config, env            | True     | Set to false to disable collection of host metrics 			|
 | `VSPHERE_LIMITED_COLLECT_DATASTORES` 		| config, env            | True     | Set to false to disable collection of datastore metrics 			|
 | `VSPHERE_LIMITED_COLLECT_VMS`        		| config, env            | True     | Set to false to disable collection of virtual machine metrics 		|

tests/unit/test_vmware_exporter.py

@@ -1,6 +1,7 @@
 import contextlib
 import datetime
 from unittest import mock
+from sys import platform
 
 import pytest
 import pytest_twisted
@@ -1525,10 +1526,15 @@ def test_vmware_resource_async_render_GET():
         b'vsphere_host': [b'127.0.0.1'],
     }
 
+    env = {
+        'VSPHERE_EXPORTER_METRICS': False,
+    }
+
     args = mock.Mock()
     args.config_file = None
 
-    resource = VMWareMetricsResource(args)
+    with mock.patch('vmware_exporter.vmware_exporter.os.environ', env):
+        resource = VMWareMetricsResource(args)
 
     with mock.patch('vmware_exporter.vmware_exporter.VmwareCollector') as Collector:
         Collector.return_value.collect.return_value = []
@@ -1649,6 +1655,39 @@ def test_vmware_resource_async_render_GET_section():
     request.finish.assert_called_with()
 
 
+@pytest.mark.skipif(platform.startswith("win"), reason="Requires Linux")
+@pytest_twisted.inlineCallbacks
+def test_vmware_resource_async_render_GET_exportermetrics():
+    request = mock.Mock()
+    request.args = {
+        b'vsphere_host': [b'127.0.0.1'],
+    }
+
+    env = {
+        'VSPHERE_EXPORTER_METRICS': True,
+    }
+
+    args = mock.Mock()
+    args.config_file = None
+
+    with mock.patch('vmware_exporter.vmware_exporter.os.environ', env):
+        resource = VMWareMetricsResource(args)
+
+    with mock.patch('vmware_exporter.vmware_exporter.VmwareCollector') as Collector:
+        Collector.return_value.collect.return_value = []
+        yield resource._async_render_GET(request)
+
+    request.setResponseCode.assert_called_with(200)
+
+    metrics = []
+    for s in request.write.call_args[0][0].decode("utf-8").splitlines():
+        if not s.startswith("#"):
+            metrics.append(s.split(' ', 1)[0].split('{', 1)[0])
+
+    assert 'process_resident_memory_bytes' in metrics
+    assert 'vmware_exporter_build_info' in metrics
+
+
 def test_config_env_multiple_sections():
     env = {
         'VSPHERE_HOST': '127.0.0.10',
@@ -1680,6 +1719,7 @@ def test_config_env_multiple_sections():
             'fetch_custom_attributes': True,
             'fetch_tags': True,
             'fetch_alarms': True,
+            'exporter_metrics': True,
             'collect_only': {
                 'datastores': True,
                 'hosts': True,
@@ -1697,6 +1737,7 @@ def test_config_env_multiple_sections():
             'fetch_custom_attributes': False,
             'fetch_tags': False,
             'fetch_alarms': False,
+            'exporter_metrics': False,
             'collect_only': {
                 'datastores': True,
                 'hosts': True,

vmware_exporter/vmware_exporter.py

@@ -44,10 +44,12 @@
 
 # Prometheus specific imports
 from prometheus_client.core import GaugeMetricFamily
-from prometheus_client import CollectorRegistry, generate_latest
+from prometheus_client import CollectorRegistry, generate_latest, Gauge
+from prometheus_client.core import REGISTRY
 
 from .helpers import batch_fetch_properties, get_bool_env
 from .defer import parallelize, run_once_property
+from .__init__ import __version__
 
 from .__init__ import __version__
 
@@ -1890,6 +1892,7 @@ def configure(self, args):
                 'fetch_custom_attributes': get_bool_env('VSPHERE_FETCH_CUSTOM_ATTRIBUTES', False),
                 'fetch_tags': get_bool_env('VSPHERE_FETCH_TAGS', False),
                 'fetch_alarms': get_bool_env('VSPHERE_FETCH_ALARMS', False),
+                'exporter_metrics': get_bool_env('VSPHERE_EXPORTER_METRICS', True),
                 'collect_only': {
                     'vms': get_bool_env('VSPHERE_COLLECT_VMS', True),
                     'vmguests': get_bool_env('VSPHERE_COLLECT_VMGUESTS', True),
@@ -1917,6 +1920,7 @@ def configure(self, args):
                 'fetch_custom_attributes': get_bool_env('VSPHERE_{}_FETCH_CUSTOM_ATTRIBUTES'.format(section), False),
                 'fetch_tags': get_bool_env('VSPHERE_{}_FETCH_TAGS'.format(section), False),
                 'fetch_alarms': get_bool_env('VSPHERE_{}_FETCH_ALARMS'.format(section), False),
+                'exporter_metrics': get_bool_env('VSPHERE_{}_EXPORTER_METRICS', section.lower() == "default"),
                 'collect_only': {
                     'vms': get_bool_env('VSPHERE_{}_COLLECT_VMS'.format(section), True),
                     'vmguests': get_bool_env('VSPHERE_{}_COLLECT_VMGUESTS'.format(section), True),
@@ -1953,6 +1957,8 @@ def generate_latest_metrics(self, request):
             logging.info("{} is not a valid section, using default".format(section))
             section = 'default'
 
+        get_exporter_metrics = self.config[section].get('exporter_metrics')
+
         if self.config[section].get('vsphere_host') and self.config[section].get('vsphere_host') != "None":
             vsphere_host = self.config[section].get('vsphere_host')
         elif request.args.get(b'target', [None])[0]:
@@ -1979,8 +1985,23 @@ def generate_latest_metrics(self, request):
         )
         metrics = yield collector.collect()
 
-        registry = CollectorRegistry()
-        registry.register(ListCollector(metrics))
+        do_metrics_registration = True
+
+        if get_exporter_metrics:
+            registry = REGISTRY
+            if 'vmware_exporter_build_info' in registry._names_to_collectors:
+                do_metrics_registration = False
+            else:
+                g = Gauge('vmware_exporter_build_info',
+                          'A metric with a constant \'1\' value labeled by version of vmware-exporter.',
+                          ["version"], registry=registry)
+                g.labels(version=__version__)
+        else:
+            registry = CollectorRegistry()
+
+        if do_metrics_registration:
+            registry.register(ListCollector(metrics))
+
         output = generate_latest(registry)
 
         request.setHeader("Content-Type", "text/plain; charset=UTF-8")