Add support for global configuration from /etc/prometheus_webhook_snm…

…p.conf.

- Default values are not shown anymore in the app help message
- Config settings are set according this priority chain: default values, global config, CLI args. This means, args passed via CLI have the highest priority.
- The config file is written in YAML, as all Prometheus config files.

Signed-off-by: Volker Theile <[email protected]>

README.md

@@ -21,6 +21,7 @@ If you want to send a test SNMP trap, then simply execute the following command.
     $ ./prometheus-webhook-snmp test
 
 # Command line parameters
+Command line parameters have precedence over global configuration settings.
 
 ## Global
 
@@ -94,6 +95,19 @@ scrape_configs:
       - targets: ['localhost:9099']
 ```
 
+# Global configuration file
+The Prometheus Alertmanager receiver can be configured via configuration file, too. The file ``/etc/prometheus-webhook-snmp.conf`` is written in YAML format. Parameters in this file have precedence over default configuration settings. Please replace hyphens in parameter names with underscores.
+
+Example configuration:
+
+```yaml
+debug: True
+snmp_retries: 1
+snmp_community: private
+host: promalertmgr.foo.com
+port: 9101
+```
+
 # SNMP schema
 
 ## Traps

debian/changelog

@@ -1,3 +1,9 @@
+prometheus-webhook-snmp (1.1-1) stable; urgency=low
+
+  * Add support for global configuration file.
+
+ -- Volker Theile <[email protected]>  Mon, 13 May 2019 16:01:19 +0200
+
 prometheus-webhook-snmp (1.0-1) stable; urgency=low
 
   * Initial Debian packaging.

debian/control

@@ -12,7 +12,8 @@ Depends: ${misc:Depends},
          python3-click,
          python3-cherrypy3,
          python3-dateutil,
-         python3-pysnmp4
+         python3-pysnmp4,
+         python3-yaml
 Priority: optional
 Description: Prometheus Alertmanager receiver for SNMP traps
  prometheus-webhook-snmp is a Prometheus Alertmanager receiver that

debian/prometheus-webhook-snmp.default

@@ -0,0 +1 @@
+PROMETHEUS_WEBHOOK_SNMP_OPTIONS=""

prometheus-webhook-snmp

@@ -8,7 +8,8 @@ import click
 from prometheus_webhook_snmp import utils
 
 
-__version__ = "1.0"
+__version__ = "1.1"
+
 
 pass_context = click.make_pass_decorator(utils.Context, ensure=True)
 
@@ -19,42 +20,27 @@ pass_context = click.make_pass_decorator(utils.Context, ensure=True)
               is_flag=True,
               help='Enable debug output.')
 @click.option('--snmp-host',
-              default='localhost',
-              show_default=True,
               help='The host (IP or FQDN) of the SNMP trap receiver.')
 @click.option('--snmp-port',
-              default=162,
-              show_default=True,
               help='The port of the SNMP trap receiver.')
 @click.option('--snmp-community',
-              default='public',
-              show_default=True,
               help='The SNMP community string.')
 @click.option('--snmp-retries',
-              default=5,
-              show_default=True,
               help='Maximum number of request retries.')
 @click.option('--snmp-timeout',
-              default=1,
-              show_default=True,
               help='Response timeout in seconds.')
 @click.option('--alert-oid-label',
-              default='oid',
-              show_default=True,
               help='The label where to find the OID.')
 @click.option('--trap-oid-prefix',
-              default='1.3.6.1.4.1.50495.15',
-              show_default=True,
               help='The OID prefix for trap variable bindings.')
 @click.option('--trap-default-oid',
-              default='1.3.6.1.4.1.50495.15.1.2.1',
-              show_default=True,
               help='The trap OID if none is found in the Prometheus alert labels.')
 @click.version_option(__version__, message="%(version)s")
 @pass_context
 def cli(ctx, debug, snmp_host, snmp_port, snmp_community, snmp_retries,
         snmp_timeout, alert_oid_label, trap_oid_prefix, trap_default_oid):
-    ctx.config['debug'] = debug
+    ctx.config.load(click.get_current_context().info_name)
+    ctx.config['debug'] = True if debug else None
     ctx.config['snmp_host'] = snmp_host
     ctx.config['snmp_port'] = snmp_port
     ctx.config['snmp_community'] = snmp_community
@@ -72,12 +58,8 @@ def cli(ctx, debug, snmp_host, snmp_port, snmp_community, snmp_retries,
 
 @cli.command(name='run', help='Start the HTTP server.')
 @click.option('--host',
-              default='0.0.0.0',
-              show_default=True,
               help='Host to use.')
 @click.option('--port',
-              default=9099,
-              show_default=True,
               help='Port to listen for Prometheus Alertmanager notifications.')
 @click.option('--metrics',
               is_flag=True,
@@ -86,7 +68,7 @@ def cli(ctx, debug, snmp_host, snmp_port, snmp_community, snmp_retries,
 def run(ctx, host, port, metrics):
     ctx.config['host'] = host
     ctx.config['port'] = port
-    ctx.config['metrics'] = metrics
+    ctx.config['metrics'] = True if metrics else None
     utils.run_http_server(ctx)
     sys.exit(0)
 

prometheus-webhook-snmp.service

@@ -3,7 +3,8 @@ Description=Prometheus Alertmanager receiver for SNMP traps
 After=network.target
 
 [Service]
-ExecStart=/usr/bin/prometheus-webhook-snmp run
+EnvironmentFile=-/etc/default/prometheus-webhook-snmp
+ExecStart=/usr/bin/prometheus-webhook-snmp $PROMETHEUS_WEBHOOK_SNMP_OPTIONS run
 ExecReload=/bin/kill -HUP $MAINPID
 Restart=on-failure
 

prometheus-webhook-snmp.spec

@@ -15,7 +15,7 @@
 # Please submit bugfixes or comments via http://bugs.opensuse.org/
 
 Name:           prometheus-webhook-snmp
-Version:        1.0
+Version:        1.1
 Release:        0
 Summary:        Prometheus Alertmanager receiver for SNMP traps
 License:        GPL-3.0
@@ -34,11 +34,13 @@ Requires:       python3-prometheus-client
 Requires:       python3-click
 %if 0%{?suse_version}
 Requires:       python3-CherryPy
+Requires:       python3-PyYAML
 %else
 Requires:       python3-cherrypy
+Requires:       python3-yaml
 %endif
 Requires:       python3-dateutil
-Requires:       python3-pysnmp
+Requires:       python3-pysnmp >= 4.3.2
 
 %description
 prometheus-webhook-snmp is a Prometheus Alertmanager receiver that

prometheus_webhook_snmp/utils.py

@@ -6,6 +6,7 @@
 import cherrypy
 import dateutil.parser
 import prometheus_client
+import yaml
 
 from pysnmp import hlapi
 
@@ -159,6 +160,72 @@ def run_http_server(ctx):
     cherrypy.quickstart(Root(ctx), config=get_http_server_config())
 
 
+class Config(dict):
+    def __init__(self):
+        super().__init__()
+        self.reset()
+
+    @staticmethod
+    def defaults():
+        """
+        Get the default configuration values.
+        :return: Returns a dictionary containing the default values.
+        :rtype: dict
+        """
+        return {
+            'debug': False,
+            'snmp_host': 'localhost',
+            'snmp_port': 162,
+            'snmp_community': 'public',
+            'snmp_retries': 5,
+            'snmp_timeout': 1,
+            'alert_oid_label': 'oid',
+            'trap_oid_prefix': '1.3.6.1.4.1.50495.15',
+            'trap_default_oid': '1.3.6.1.4.1.50495.15.1.2.1',
+            'host': '0.0.0.0',
+            'port': 9099,
+            'metrics': False
+        }
+
+    def reset(self, name=None):
+        """
+        Reset to default values. If a name is specified, only the named
+        configuration setting is reset to default.
+        :param name: The name of the configuration setting. Defaults to 'None'.
+        :type name: str
+        """
+        if name is None:
+            self.clear()
+            self.update(Config.defaults())
+        else:
+            self[name] = Config.defaults()[name]
+
+    def load(self, prog_name):
+        """
+        Load a configuration file from disk.
+        :param prog_name: The name of the program.
+        :type prog_name: str
+        """
+        file_name = '/etc/{}.conf'.format(prog_name)
+        try:
+            with open(file_name, 'r') as stream:
+                config = yaml.safe_load(stream)
+                self.update(config)
+        except (IOError, FileNotFoundError):
+            pass
+
+    def __setitem__(self, key, value):
+        """
+        Set self[key] to value. Ignore 'None' values.
+        :param key: The name of the key.
+        :type key: str
+        :param value: The value of the key.
+        :type value: bool|int|str
+        """
+        if value is not None:
+            super().__setitem__(key, value)
+
+
 class Telemetry:
     def __init__(self):
         self.metrics = {
@@ -183,14 +250,7 @@ def generate(self):
 
 class Context:
     def __init__(self):
-        self.config = {
-            key: None
-            for key in [
-                'host', 'port', 'metrics', 'snmp_host', 'snmp_port',
-                'snmp_community', 'snmp_retries', 'snmp_timeout',
-                'alert_oid_label', 'trap_default_oid', 'trap_oid_prefix'
-            ]
-        }
+        self.config = Config()
         self.telemetry = Telemetry()
 
 

requirements.txt

@@ -1,7 +1,10 @@
 CherryPy==18.1.1
 Click==7.0
-pysnmp==4.4.9
-python-dateutil==2.8.0
-pytest==4.4.0
-pylint==2.3.1
+PyYAML==5.1
+mock==3.0.5
 prometheus_client==0.6.0
+pyfakefs==3.5.8
+pylint==2.3.1
+pysnmp>=4.3.2
+pytest==4.4.0
+python-dateutil==2.8.0

tests/test_misc.py

@@ -1,6 +1,9 @@
 import unittest
+import mock
 
-from prometheus_webhook_snmp.utils import parse_notification
+from pyfakefs import fake_filesystem
+
+from prometheus_webhook_snmp.utils import parse_notification, Config
 
 NOTIFICATION_FIRING = {
     'receiver': 'test-01',
@@ -110,3 +113,30 @@ def test_parse_notification_no_oid(self):
         self.assertEqual(trap_data['labels'], {'foo': 'abc', 'bar': 123})
         self.assertEqual(trap_data['timestamp'], 1554110387)
         self.assertIsInstance(trap_data['rawdata'], dict)
+
+
+class ConfigTestCase(unittest.TestCase):
+    fs = fake_filesystem.FakeFilesystem()
+    f_open = fake_filesystem.FakeFileOpen(fs)
+
+    def test_defaults(self):
+        self.assertIsInstance(Config.defaults(), dict)
+
+    def test_reset(self):
+        config = Config()
+        config['snmp_community'] = 'private'
+        config.reset('snmp_community')
+        self.assertEqual(config['snmp_community'], Config.defaults()['snmp_community'])
+
+    def test_reset_all(self):
+        config = Config()
+        config['foo'] = 'bar'
+        config.reset()
+        self.assertDictEqual(config, Config.defaults())
+
+    @mock.patch('builtins.open', new=f_open)
+    def test_load(self):
+        self.fs.create_file('/etc/abc.conf', contents='''foo: bar\n''')
+        config = Config()
+        config.load('abc')
+        self.assertEqual(config['foo'], 'bar')