Add Google pubsub component (#20049)

* Add google pubsub component

* Add tests and requirements

* Make python3.5 compatible

* Fix linting

* Fix pubsub test

* Code review comments

* Add missing docstrings

* Update requirements_all

* Code review comment

- Remove pylint ignores
- Don't modify global environment

homeassistant/components/google_pubsub/__init__.py

@@ -0,0 +1,99 @@
+"""
+Support for Google Cloud Pub/Sub.
+
+For more details about this component, please refer to the documentation at
+https://home-assistant.io/components/google_pubsub/
+"""
+import datetime
+import json
+import logging
+import os
+from typing import Any, Dict
+
+import voluptuous as vol
+
+from homeassistant.const import (
+    EVENT_STATE_CHANGED, STATE_UNAVAILABLE, STATE_UNKNOWN)
+from homeassistant.core import Event, HomeAssistant
+import homeassistant.helpers.config_validation as cv
+from homeassistant.helpers.entityfilter import FILTER_SCHEMA
+
+_LOGGER = logging.getLogger(__name__)
+
+REQUIREMENTS = ['google-cloud-pubsub==0.39.1']
+
+DOMAIN = 'google_pubsub'
+
+CONF_PROJECT_ID = 'project_id'
+CONF_TOPIC_NAME = 'topic_name'
+CONF_SERVICE_PRINCIPAL = 'credentials_json'
+CONF_FILTER = 'filter'
+
+CONFIG_SCHEMA = vol.Schema({
+    DOMAIN: vol.Schema({
+        vol.Required(CONF_PROJECT_ID): cv.string,
+        vol.Required(CONF_TOPIC_NAME): cv.string,
+        vol.Required(CONF_SERVICE_PRINCIPAL): cv.string,
+        vol.Required(CONF_FILTER): FILTER_SCHEMA
+    }),
+}, extra=vol.ALLOW_EXTRA)
+
+
+def setup(hass: HomeAssistant, yaml_config: Dict[str, Any]):
+    """Activate Google Pub/Sub component."""
+    from google.cloud import pubsub_v1
+
+    config = yaml_config[DOMAIN]
+    project_id = config[CONF_PROJECT_ID]
+    topic_name = config[CONF_TOPIC_NAME]
+    service_principal_path = os.path.join(hass.config.config_dir,
+                                          config[CONF_SERVICE_PRINCIPAL])
+
+    if not os.path.isfile(service_principal_path):
+        _LOGGER.error("Path to credentials file cannot be found")
+        return False
+
+    entities_filter = config[CONF_FILTER]
+
+    publisher = (pubsub_v1
+                 .PublisherClient
+                 .from_service_account_json(service_principal_path)
+                 )
+
+    topic_path = publisher.topic_path(project_id,  # pylint: disable=E1101
+                                      topic_name)
+
+    encoder = DateTimeJSONEncoder()
+
+    def send_to_pubsub(event: Event):
+        """Send states to Pub/Sub."""
+        state = event.data.get('new_state')
+        if (state is None
+                or state.state in (STATE_UNKNOWN, '', STATE_UNAVAILABLE)
+                or not entities_filter(state.entity_id)):
+            return
+
+        as_dict = state.as_dict()
+        data = json.dumps(
+            obj=as_dict,
+            default=encoder.encode
+        ).encode('utf-8')
+
+        publisher.publish(topic_path, data=data)
+
+    hass.bus.listen(EVENT_STATE_CHANGED, send_to_pubsub)
+
+    return True
+
+
+class DateTimeJSONEncoder(json.JSONEncoder):
+    """Encode python objects.
+
+    Additionally add encoding for datetime objects as isoformat.
+    """
+
+    def default(self, o):  # pylint: disable=E0202
+        """Implement encoding logic."""
+        if isinstance(o, datetime.datetime):
+            return o.isoformat()
+        return super().default(o)

requirements_all.txt

@@ -471,6 +471,9 @@ gntp==1.0.3
 # homeassistant.components.google
 google-api-python-client==1.6.4
 
+# homeassistant.components.google_pubsub
+google-cloud-pubsub==0.39.1
+
 # homeassistant.components.googlehome
 googledevices==1.0.2
 

tests/components/google_pubsub/test_pubsub.py

@@ -0,0 +1,22 @@
+"""The tests for the Google Pub/Sub component."""
+from datetime import datetime
+
+from homeassistant.components.google_pubsub import (
+    DateTimeJSONEncoder as victim)
+
+
+class TestDateTimeJSONEncoder(object):
+    """Bundle for DateTimeJSONEncoder tests."""
+
+    def test_datetime(self):
+        """Test datetime encoding."""
+        time = datetime(2019, 1, 13, 12, 30, 5)
+        assert victim().encode(time) == '"2019-01-13T12:30:05"'
+
+    def test_no_datetime(self):
+        """Test integer encoding."""
+        assert victim().encode(42) == '42'
+
+    def test_nested(self):
+        """Test dictionary encoding."""
+        assert victim().encode({'foo': 'bar'}) == '{"foo": "bar"}'