Validate API on starting remote instance

README.md

@@ -120,6 +120,22 @@ Because each slave maintains it's own ServiceRegistry it is possible to have mul
 
 ![home assistant master-slave architecture](https://raw.github.com/balloob/home-assistant/master/docs/architecture-remote.png)
 
+A slave instance can be started with the following code.
+
+```python
+import homeassistant.remote as remote
+import homeassistant.components.http as http
+
+remote_api = remote.API("remote_host_or_ip", "remote_api_password")
+
+hass = remote.HomeAssistant(remote_api)
+
+http.setup(hass, "my_local_api_password")
+
+hass.start()
+hass.block_till_stopped()
+```
+
 Web interface and API
 ---------------------
 Home Assistent runs a webserver accessible on port 8123. 
@@ -143,6 +159,15 @@ Other status codes that can occur are:
 
 The api supports the following actions:
 
+**/api - GET**<br>
+Returns message if API is up and running.
+
+```json
+{
+  "message": "API running."
+}
+```
+
 **/api/events - GET**<br>
 Returns a dict with as keys the events and as value the number of listeners.
 

homeassistant/components/http/__init__.py

@@ -17,6 +17,13 @@ Other status codes that can occur are:
 
 The api supports the following actions:
 
+/api - GET
+Returns message if API is up and running.
+Example result:
+{
+  "message": "API running."
+}
+
 /api/states - GET
 Returns a list of entities for which a state is available
 Example result:
@@ -112,6 +119,10 @@ def setup(hass, api_password, server_port=None, server_host=None):
         lambda event:
         threading.Thread(target=server.start, daemon=True).start())
 
+    # If no local api set, set one with known information
+    if isinstance(hass, rem.HomeAssistant) and hass.local_api is None:
+        hass.local_api = rem.API(util.get_local_ip(), api_password, server_port)
+
 
 class HomeAssistantHTTPServer(ThreadingMixIn, HTTPServer):
     """ Handle HTTP requests in a threaded fashion. """
@@ -149,6 +160,9 @@ class RequestHandler(BaseHTTPRequestHandler):
         ('POST', re.compile(URL_FIRE_EVENT), '_handle_fire_event'),
         ('POST', re.compile(URL_CALL_SERVICE), '_handle_call_service'),
 
+        # /api - for validation purposes
+        ('GET', rem.URL_API, '_handle_get_api'),
+
         # /states
         ('GET', rem.URL_API_STATES, '_handle_get_api_states'),
         ('GET',
@@ -619,6 +633,11 @@ class RequestHandler(BaseHTTPRequestHandler):
             self._message(
                 "Invalid JSON for service_data", HTTP_UNPROCESSABLE_ENTITY)
 
+    # pylint: disable=unused-argument
+    def _handle_get_api(self, path_match, data):
+        """ Renders the debug interface. """
+        self._message("API running.")
+
     # pylint: disable=unused-argument
     def _handle_get_api_states(self, path_match, data):
         """ Returns a dict containing all entity ids and their state. """

homeassistant/remote.py

@@ -12,6 +12,7 @@ HomeAssistantError will be raised.
 import threading
 import logging
 import json
+import enum
 import urllib.parse
 
 import requests
@@ -20,6 +21,7 @@ import homeassistant as ha
 
 SERVER_PORT = 8123
 
+URL_API = "/api/"
 URL_API_STATES = "/api/states"
 URL_API_STATES_ENTITY = "/api/states/{}"
 URL_API_EVENTS = "/api/events"
@@ -32,6 +34,18 @@ METHOD_GET = "get"
 METHOD_POST = "post"
 
 
+class APIStatus(enum.Enum):
+    """ Represents API status. """
+
+    OK = "ok"
+    INVALID_PASSWORD = "invalid_password"
+    CANNOT_CONNECT = "cannot_connect"
+    UNKNOWN = "unknown"
+
+    def __str__(self):
+        return self.value
+
+
 class API(object):
     """ Object to pass around Home Assistant API location and credentials. """
     # pylint: disable=too-few-public-methods
@@ -41,6 +55,13 @@ class API(object):
         self.port = port or SERVER_PORT
         self.api_password = api_password
         self.base_url = "http://{}:{}".format(host, self.port)
+        self.status = None
+
+    def validate_api(self, force_validate=False):
+        if self.status is None or force_validate:
+            self.status = validate_api(self)
+
+        return self.status == APIStatus.OK
 
     def __call__(self, method, path, data=None):
         """ Makes a call to the Home Assistant api. """
@@ -64,9 +85,13 @@ class HomeAssistant(ha.HomeAssistant):
     """ Home Assistant that forwards work. """
     # pylint: disable=super-init-not-called
 
-    def __init__(self, local_api, remote_api):
+    def __init__(self, remote_api, local_api=None):
-        self.local_api = local_api
+        if not remote_api.validate_api():
+            raise ha.HomeAssistantError(
+                "Remote API not valid: {}".format(remote_api.status))
+
         self.remote_api = remote_api
+        self.local_api = local_api
 
         self._pool = pool = ha.create_worker_pool()
 
@@ -75,6 +100,14 @@ class HomeAssistant(ha.HomeAssistant):
         self.states = StateMachine(self.bus, self.remote_api)
 
     def start(self):
+        # If there is no local API setup but we do want to connect with remote
+        # We create a random password and set up a local api
+        if self.local_api is None:
+            import homeassistant.components.http as http
+            import random
+
+            http.setup(self, '%030x'.format(random.randrange(16**30)))
+
         ha.Timer(self)
 
         # Setup that events from remote_api get forwarded to local_api
@@ -201,6 +234,24 @@ class JSONEncoder(json.JSONEncoder):
         return json.JSONEncoder.default(self, obj)
 
 
+def validate_api(api):
+    """ Makes a call to validate API. """
+    try:
+        req = api(METHOD_GET, URL_API)
+
+        if req.status_code == 200:
+            return APIStatus.OK
+
+        elif req.status_code == 401:
+            return APIStatus.INVALID_PASSWORD
+
+        else:
+            return APIStatus.UNKNOWN
+
+    except ha.HomeAssistantError:
+        return APIStatus.CANNOT_CONNECT
+
+
 def connect_remote_events(from_api, to_api):
     """ Sets up from_api to forward all events to to_api. """
 

homeassistant/util.py

@@ -9,6 +9,8 @@ import queue
 import datetime
 import re
 import enum
+import socket
+import os
 
 RE_SANITIZE_FILENAME = re.compile(r'(~|\.\.|/|\\)')
 RE_SLUGIFY = re.compile(r'[^A-Za-z0-9_]+')
@@ -124,6 +126,23 @@ def ensure_unique_string(preferred_string, current_strings):
     return string
 
 
+# Taken from: http://stackoverflow.com/a/11735897
+def get_local_ip():
+    """ Tries to determine the local IP address of the machine. """
+    try:
+        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+
+        # Use Google Public DNS server to determine own IP
+        sock.connect(('8.8.8.8', 80))
+        ip_addr = sock.getsockname()[0]
+        sock.close()
+
+        return ip_addr
+
+    except socket.error:
+        return socket.gethostbyname(socket.gethostname())
+
+
 class OrderedEnum(enum.Enum):
     """ Taken from Python 3.4.0 docs. """
     # pylint: disable=no-init