Fix bug in exporter

Change-Id: I61dd306f8692dbf320a9dde852f52bf9185cae4b
diff --git a/exporter.py b/exporter.py
index bb8c2d0..ee8ce88 100644
--- a/exporter.py
+++ b/exporter.py
@@ -12,7 +12,7 @@
         self.polling_interval_seconds = polling_interval_seconds
 
         self.num_configured_devices = Gauge("num_configured_devices", "Number of configured devices")
-        self.num_configured_devices = Gauge("num_reachable_devices", "Number of reachable devices")
+        self.num_reachable_devices = Gauge("num_reachable_devices", "Number of reachable devices")
 
     def run_metrics_loop(self):
         while True:
@@ -21,10 +21,10 @@
 
     def fetch(self):
         resp = requests.get(url=f"http://localhost:{self.app_port}/devices")
-        self.num_configured_devices = len(json.loads(resp.text))
+        self.num_configured_devices.set(len(json.loads(resp.text)))
 
         resp = requests.get(url=f"http://localhost:{self.app_port}/devices/reachable")
-        self.num_configured_devices = len(json.loads(resp.text))
+        self.num_reachable_devices.set(len(json.loads(resp.text)))
 
 def main():
     polling_interval_seconds = int(os.getenv("POLLING_INTERVAL_SECONDS", "5"))