Add dmesg monitor

rootfs/standard/var/www/mynode/mynode.py

@@ -971,6 +971,9 @@ def start_threads():
     public_ip_thread = BackgroundThread(find_public_ip, 60*60*12) # 12-hour repeat
     public_ip_thread.start()
     threads.append(public_ip_thread)
+    dmesg_thread = BackgroundThread(monitor_dmesg, 60) # Runs forever, restart after 60 if it fails 
+    dmesg_thread.start()
+    threads.append(dmesg_thread)
 
     app.logger.info("STARTED {} THREADS".format(len(threads)))
 

rootfs/standard/var/www/mynode/thread_functions.py

@@ -155,4 +155,32 @@ def find_public_ip():
 
 # Updated: Check ins now happen in different process. This will just restart the service to force a new check in.
 def check_in():
-    os.system("systemctl restart check_in")
+    os.system("systemctl restart check_in")
+
+
+def dmesg_log_clear():
+    f = open("/tmp/dmesg", "w")
+    f.write("")
+    f.close()
+def dmesg_log(msg):
+    print(msg)
+    f = open("/tmp/dmesg", "a")
+    f.write(msg)
+    f.close()
+
+# This will monitor dmesg for system errors or issues
+def monitor_dmesg():
+    dmesg_log_clear()
+    cmd = ["dmesg","--follow"]
+    dmesg = subprocess.Popen(cmd, stdout=subprocess.PIPE)
+    while True:
+        l = dmesg.stdout.readline()
+        try:
+            l = l.encode('utf-8', 'ignore').decode('utf-8')
+
+            #TODO: Check for things like OOM, etc...
+            
+            dmesg_log(l)
+        except Exception as e:
+            dmesg_log("dmesg exception: "+str(e))
+