Add PlatformCollector to collect information about the platform (#152)

Add PlatformCollector to collect information about the platform

Python, machine and system information is collected once at startup, and
exposed as labels on a metric with value 1.

Author: mortenlj

README.md

@@ -206,6 +206,13 @@ other processes, for example:
 ProcessCollector(namespace='mydaemon', pid=lambda: open('/var/run/daemon.pid').read())
 ```
 
+### Platform Collector
+
+The client also automatically exports some metadata about Python. If using Jython,
+metadata about the JVM in use is also included. This information is available as 
+labels on the `python_info` metric. The value of the metric is 1, since it is the 
+labels that carry information.
+
 ## Exporting
 
 There are several options for exporting metrics.

prometheus_client/__init__.py

@@ -3,6 +3,7 @@
 from . import core
 from . import exposition
 from . import process_collector
+from . import platform_collector
 
 __all__ = ['Counter', 'Gauge', 'Summary', 'Histogram']
 # http://stackoverflow.com/questions/19913653/no-unicode-in-all-for-a-packages-init
@@ -31,6 +32,9 @@
 ProcessCollector = process_collector.ProcessCollector
 PROCESS_COLLECTOR = process_collector.PROCESS_COLLECTOR
 
+PlatformCollector = platform_collector.PlatformCollector
+PLATFORM_COLLECTOR = platform_collector.PLATFORM_COLLECTOR
+
 
 if __name__ == '__main__':
     c = Counter('cc', 'A counter')

prometheus_client/platform_collector.py

@@ -0,0 +1,58 @@
+#!/usr/bin/env python
+# -*- coding: utf-8
+from __future__ import unicode_literals
+
+import platform as pf
+
+from . import core
+
+
+class PlatformCollector(object):
+    """Collector for python platform information"""
+
+    def __init__(self, registry=core.REGISTRY, platform=None):
+        self._platform = pf if platform is None else platform
+        info = self._info()
+        system = self._platform.system()
+        if system == "Java":
+            info.update(self._java())
+        self._metrics = [
+            self._add_metric("python_info", "Python platform information", info)
+        ]
+        if registry:
+            registry.register(self)
+
+    def collect(self):
+        return self._metrics
+
+    @staticmethod
+    def _add_metric(name, documentation, data):
+        labels = data.keys()
+        values = [data[k] for k in labels]
+        g = core.GaugeMetricFamily(name, documentation, labels=labels)
+        g.add_metric(values, 1)
+        return g
+
+    def _info(self):
+        major, minor, patchlevel = self._platform.python_version_tuple()
+        return {
+            "version": self._platform.python_version(),
+            "implementation": self._platform.python_implementation(),
+            "major": major,
+            "minor": minor,
+            "patchlevel": patchlevel
+        }
+
+    def _java(self):
+        java_version, _, vminfo, osinfo = self._platform.java_ver()
+        vm_name, vm_release, vm_vendor = vminfo
+        return {
+            "jvm_version": java_version,
+            "jvm_release": vm_release,
+            "jvm_vendor": vm_vendor,
+            "jvm_name": vm_name
+        }
+
+
+PLATFORM_COLLECTOR = PlatformCollector()
+"""PlatformCollector in default Registry REGISTRY"""

tests/test_platform_collector.py

@@ -0,0 +1,69 @@
+from __future__ import unicode_literals
+
+import unittest
+
+from prometheus_client import CollectorRegistry, PlatformCollector
+
+
+class TestPlatformCollector(unittest.TestCase):
+    def setUp(self):
+        self.registry = CollectorRegistry()
+        self.platform = _MockPlatform()
+
+    def test_python_info(self):
+        PlatformCollector(registry=self.registry, platform=self.platform)
+        self.assertLabels("python_info", {
+            "version": "python_version",
+            "implementation": "python_implementation",
+            "major": "pvt_major",
+            "minor": "pvt_minor",
+            "patchlevel": "pvt_patchlevel"
+        })
+
+    def test_system_info_java(self):
+        self.platform._system = "Java"
+        PlatformCollector(registry=self.registry, platform=self.platform)
+        self.assertLabels("python_info", {
+            "version": "python_version",
+            "implementation": "python_implementation",
+            "major": "pvt_major",
+            "minor": "pvt_minor",
+            "patchlevel": "pvt_patchlevel",
+            "jvm_version": "jv_release",
+            "jvm_release": "vm_release",
+            "jvm_vendor": "vm_vendor",
+            "jvm_name": "vm_name"
+        })
+
+    def assertLabels(self, name, labels):
+        for metric in self.registry.collect():
+            for n, l, value in metric.samples:
+                if n == name:
+                    assert l == labels
+                    return
+        assert False
+
+
+class _MockPlatform(object):
+    def __init__(self):
+        self._system = "system"
+
+    def python_version_tuple(self):
+        return "pvt_major", "pvt_minor", "pvt_patchlevel"
+
+    def python_version(self):
+        return "python_version"
+
+    def python_implementation(self):
+        return "python_implementation"
+
+    def system(self):
+        return self._system
+
+    def java_ver(self):
+        return (
+            "jv_release",
+            "jv_vendor",
+            ("vm_name", "vm_release", "vm_vendor"),
+            ("os_name", "os_version", "os_arch")
+        )