add timeout exception handling.

At the time of writing, I would find the relay.service wouldn't crash so it
couldn't be restarted. Instead, it would hang and I think it's to do with
the HTTP request not timing out properly. I can't confirm this yet so I've
added in an exception case to help with monitoring the issue.

This is a 'work-in-progress' commit.

relay.py

@@ -4,6 +4,7 @@ import RPi.GPIO as GPIO
 import time
 import requests
 import platform
+import datetime
 
 relay_pin = 11
 #GPIO.setmode(GPIO.BCM) # GPIO numbers instead of board numbers.
@@ -18,7 +19,7 @@ def get_api_url():
         return "http://ritherdon.abbether.net/api/readings/latest/1"
     elif (device_id == "gallery2"):
         return "http://ritherdon.abbether.net/api/readings/latest/2"
-      
+
 # Make sure this is valid.
 # api_url = "http://ritherdon.abbether.net/api/readings/add/1"
 api_url = get_api_url() # Saves having to do the if-check every call.
@@ -27,7 +28,8 @@ def main():
     try:
         while True:
             # Make sure the U.R.L. is valid.
-            r = requests.get(api_url)
+            s = requests.Session()
+            r = s.get(api_url, timeout=5)
             # print(r.status_code) # For testing.
             data = r.json()
             # print(data) # For testing.
@@ -43,6 +45,16 @@ def main():
                 GPIO.output(relay_pin, GPIO.LOW)
     except KeyboardInterrupt:
         print("[INFO] KEYBOARD INTERRUPT: quitting program.")
+    except requests.exceptions.ConnectionError:
+        pause = 60
+        time.sleep(60)
+        print(f"[WARNING] MAX. REQUESTS EXCEEDED: Pausing requests for {pause} seconds...")
+        pass
+    except requests.exceptions.Timeout:
+        t_stamp = datetime.datetime.now()
+        print(f"[WARNING] TIMEOUT EXCEPTION: Request timed-out at {t_stamp}.")
+        time.sleep(60)
+        pass
     except Exception as e:
         print(f"[ERROR] GENERAL EXCEPTION: {e}")
     finally: