SNMP sensor (#2244)

* Add snmp sensor

* Add ATTR_UNIT_OF_MEASUREMENT

.coveragerc

@@ -178,6 +178,7 @@ omit =
     homeassistant/components/sensor/openweathermap.py
     homeassistant/components/sensor/rest.py
     homeassistant/components/sensor/sabnzbd.py
+    homeassistant/components/sensor/snmp.py
     homeassistant/components/sensor/speedtest.py
     homeassistant/components/sensor/steam_online.py
     homeassistant/components/sensor/supervisord.py

homeassistant/components/sensor/snmp.py

@@ -0,0 +1,134 @@
+"""
+Support for displaying collected data over SNMP.
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/sensor.snmp/
+"""
+import logging
+from datetime import timedelta
+import voluptuous as vol
+
+from homeassistant.helpers.entity import Entity
+from homeassistant.const import (CONF_HOST, CONF_PLATFORM, CONF_NAME,
+                                 CONF_PORT, ATTR_UNIT_OF_MEASUREMENT)
+from homeassistant.util import Throttle
+
+REQUIREMENTS = ['pysnmp==4.3.2']
+
+_LOGGER = logging.getLogger(__name__)
+
+DEFAULT_NAME = "SNMP"
+DEFAULT_COMMUNITY = "public"
+DEFAULT_PORT = "161"
+CONF_COMMUNITY = "community"
+CONF_BASEOID = "baseoid"
+
+PLATFORM_SCHEMA = vol.Schema({
+    vol.Required(CONF_PLATFORM): 'snmp',
+    vol.Optional(CONF_NAME): vol.Coerce(str),
+    vol.Required(CONF_HOST): vol.Coerce(str),
+    vol.Optional(CONF_PORT): vol.Coerce(int),
+    vol.Optional(CONF_COMMUNITY): vol.Coerce(str),
+    vol.Required(CONF_BASEOID): vol.Coerce(str),
+    vol.Optional(ATTR_UNIT_OF_MEASUREMENT): vol.Coerce(str),
+})
+
+# Return cached results if last scan was less then this time ago.
+MIN_TIME_BETWEEN_UPDATES = timedelta(seconds=10)
+
+
+# pylint: disable=too-many-locals
+def setup_platform(hass, config, add_devices, discovery_info=None):
+    """Setup the SNMP sensor."""
+    from pysnmp.hlapi import (getCmd, CommunityData, SnmpEngine,
+                              UdpTransportTarget, ContextData, ObjectType,
+                              ObjectIdentity)
+
+    host = config.get(CONF_HOST)
+    port = config.get(CONF_PORT, DEFAULT_PORT)
+    community = config.get(CONF_COMMUNITY, DEFAULT_COMMUNITY)
+    baseoid = config.get(CONF_BASEOID)
+
+    errindication, _, _, _ = next(
+        getCmd(SnmpEngine(),
+               CommunityData(community, mpModel=0),
+               UdpTransportTarget((host, port)),
+               ContextData(),
+               ObjectType(ObjectIdentity(baseoid))))
+
+    if errindication:
+        _LOGGER.error('Please check the details in the configuration file')
+        return False
+    else:
+        data = SnmpData(host, port, community, baseoid)
+        add_devices([SnmpSensor(data,
+                                config.get('name', DEFAULT_NAME),
+                                config.get('unit_of_measurement'))])
+
+
+class SnmpSensor(Entity):
+    """Representation of a SNMP sensor."""
+
+    def __init__(self, data, name, unit_of_measurement):
+        """Initialize the sensor."""
+        self.data = data
+        self._name = name
+        self._state = None
+        self._unit_of_measurement = unit_of_measurement
+        self.update()
+
+    @property
+    def name(self):
+        """Return the name of the sensor."""
+        return self._name
+
+    @property
+    def state(self):
+        """Return the state of the sensor."""
+        return self._state
+
+    @property
+    def unit_of_measurement(self):
+        """Return the unit the value is expressed in."""
+        return self._unit_of_measurement
+
+    def update(self):
+        """Get the latest data and updates the states."""
+        self.data.update()
+        self._state = self.data.value
+
+
+class SnmpData(object):
+    """Get the latest data and update the states."""
+
+    # pylint: disable=too-few-public-methods
+    def __init__(self, host, port, community, baseoid):
+        """Initialize the data object."""
+        self._host = host
+        self._port = port
+        self._community = community
+        self._baseoid = baseoid
+        self.value = None
+
+    @Throttle(MIN_TIME_BETWEEN_UPDATES)
+    def update(self):
+        """Get the latest data from the remote SNMP capable host."""
+        from pysnmp.hlapi import (getCmd, CommunityData, SnmpEngine,
+                                  UdpTransportTarget, ContextData, ObjectType,
+                                  ObjectIdentity)
+        errindication, errstatus, errindex, restable = next(
+            getCmd(SnmpEngine(),
+                   CommunityData(self._community, mpModel=0),
+                   UdpTransportTarget((self._host, self._port)),
+                   ContextData(),
+                   ObjectType(ObjectIdentity(self._baseoid)))
+            )
+
+        if errindication:
+            _LOGGER.error("SNMP error: %s", errindication)
+        elif errstatus:
+            _LOGGER.error('SNMP error: %s at %s', errstatus.prettyPrint(),
+                          errindex and restable[-1][int(errindex) - 1] or '?')
+        else:
+            for resrow in restable:
+                self.value = resrow[-1]

requirements_all.txt

@@ -262,6 +262,7 @@ pyowm==2.3.1
 pyserial<=3.0
 
 # homeassistant.components.device_tracker.snmp
+# homeassistant.components.sensor.snmp
 pysnmp==4.3.2
 
 # homeassistant.components.sensor.forecast