provide auto registration facility for collectors (#18)

To provide more than one simple collector we refactor the registration
of collectors to do this automatically.
From now all collectors that follows the convention for new collectors.
We also add a real life collector for load average (1, 5, 15).
Finally we prepare the new major release.

Author: cmeissner

.bumpversion.cfg

@@ -1,6 +1,6 @@
 [bumpversion]
 commit = True
 tag = False
-current_version = 0.1.0
+current_version = 1.0.0
 
 [bumpversion:file:setup.py]

CHANGELOG.md

@@ -13,6 +13,17 @@ This project adheres to [Semantic Versioning](http://semver.org/) and [Keep a Ch
 
 ### Breaks
 
+## 1.0.0 - (2021-03-22)
+
+### New
+
+* now it is simplier to add new collectors. You have to simply follow the naming convention
+* add loadavg collector as a real life example
+
+### Breaks
+
+* change load and registration behavior for collectors
+
 ## 0.1.0 - (2021-03-04)
 
 ### Changes

docs/plugins/p3exporter.collector.rst

@@ -5,3 +5,22 @@ p3exporter.collector package
    :members:
    :undoc-members:
    :show-inheritance:
+
+Submodules
+----------
+
+p3exporter.collector.loadavg module
+-----------------------------------
+
+.. automodule:: p3exporter.collector.loadavg
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+p3exporter.collector.my module
+------------------------------
+
+.. automodule:: p3exporter.collector.my
+   :members:
+   :undoc-members:
+   :show-inheritance:

p3.yml

@@ -1,2 +1,5 @@
 exporter_name: "Python prammable Prometheus exporter"
+collectors:
+  - loadavg
+  - my
 credentials:

p3exporter/__init__.py

@@ -8,9 +8,7 @@
 import sys
 import time
 
-from prometheus_client.core import REGISTRY
-
-from p3exporter.collector import MyCollector, CollectorConfig
+from p3exporter.collector import Collector, CollectorConfig
 from p3exporter.web import create_app
 
 
@@ -43,8 +41,7 @@ def main():
         cfg = yaml.load(config_file, Loader=yaml.SafeLoader)
     collector_config = CollectorConfig(**cfg)
 
-    collector = MyCollector(collector_config)
-    REGISTRY.register(collector)
+    Collector(collector_config)
 
     app = create_app(collector_config)
 

p3exporter/collector/__init__.py

@@ -1,8 +1,9 @@
 """Entry point for collector sub module."""
-import random
-import time
+import inflection
+import logging
 
-from prometheus_client.core import GaugeMetricFamily
+from importlib import import_module
+from prometheus_client.core import REGISTRY
 
 
 class CollectorConfig(object):
@@ -16,6 +17,7 @@ def __init__(self, **kwargs):
         :raises Exception: Raises an exception if credentials are not well configured.
         """
         self.exporter_name = kwargs.pop('exporter_name', None)
+        self.collectors = kwargs.pop('collectors', [])
         self.credentials = kwargs.pop('credentials', None)
 
         # do some fancy checks on configuration parameters
@@ -27,23 +29,25 @@ def __init__(self, **kwargs):
             raise Exception('Credential is not fully configured.')
 
 
-class MyCollector(object):
-    """A sample collector.
+class Collector(object):
+    """Base class to load collectors.
 
-    It does not really do much. It only runs a method and return the time it runs as a gauge metric.
+    All collectors have to be placed inside the directory `collector`. You have to follow the naming convention:
+
+    1. Place the collector code in a <name>.py file (e.g. `my.py`)
+    2. Within the file <name>.py` a class <Name>Collector (e.g. `MyController`) needs to be defined.
+       This is the main collector class which will be imported, instantiate and registered automatically.
     """
 
     def __init__(self, config: CollectorConfig):
-        """Instanciate a MyCollector object."""
-        pass
-
-    def collect(self):
-        """Collect the metrics."""
-        self.timer = time.perf_counter()
-        _run_process()
-        runtime = time.perf_counter() - self.timer
-        yield GaugeMetricFamily('my_process_runtime', 'Time a process runs in seconds', value=runtime)
-
-def _run_process():
-    """Sample function to ran a command for metrics."""
-    time.sleep(random.random()) # nosec
+        for c in config.collectors:
+            try:
+                collector_module = import_module("p3exporter.collector.{}".format(c), package=None)
+                collector_class = getattr(collector_module, "{0}Collector".format(inflection.camelize(c)))
+                collector = collector_class(config)
+                REGISTRY.register(collector)
+                logging.info("Collector '{0}' was loaded and registred sucessfully".format(c))
+            except ModuleNotFoundError as e:
+                logging.warning("Collector '{0}' not loaded: {1}".format(c, e.msg))
+            except AttributeError as e:
+                logging.warning("Collector '{0}' not loaded: {1}".format(c, e))

p3exporter/collector/loadavg.py

@@ -0,0 +1,20 @@
+import os
+
+from p3exporter.collector import CollectorConfig
+from prometheus_client.core import GaugeMetricFamily
+
+class LoadavgCollector(object):
+
+    def __init__(self, config: CollectorConfig):
+        """Instanciate a CpuCollector object."""
+        pass
+
+    def collect(self):
+        """Collect load avg for 1, 5 and 15 minutes interval.
+
+        Returns three gauge metrics. One for each load.
+        """
+        self.avg1, self.avg5, self.avg15 = os.getloadavg()
+        yield GaugeMetricFamily('load_avg_1', "1m load average.", value=self.avg1)
+        yield GaugeMetricFamily('load_avg_5', "5m load average.", value=self.avg5)
+        yield GaugeMetricFamily('load_avg_15', "15m load average.", value=self.avg15)

p3exporter/collector/my.py

@@ -0,0 +1,26 @@
+import random
+import time
+
+from p3exporter.collector import CollectorConfig
+from prometheus_client.core import GaugeMetricFamily
+
+class MyCollector(object):
+    """A sample collector.
+
+    It does not really do much. It only runs a method and return the time it runs as a gauge metric.
+    """
+
+    def __init__(self, config: CollectorConfig):
+        """Instanciate a MyCollector object."""
+        pass
+
+    def collect(self):
+        """Collect the metrics."""
+        self.timer = time.perf_counter()
+        _run_process()
+        runtime = time.perf_counter() - self.timer
+        yield GaugeMetricFamily('my_process_runtime', 'Time a process runs in seconds', value=runtime)
+
+def _run_process():
+    """Sample function to ran a command for metrics."""
+    time.sleep(random.random()) # nosec

requirements-dev.txt

@@ -4,6 +4,7 @@ flake8
 flake8-colors
 flake8-docstrings
 flask
+inflection
 twine
 setuptools
 PyYAML

requirements.txt

@@ -1,3 +1,4 @@
+inflection
 prometheus-client
 PyYAML
 flask